Thèses sur le sujet « Helminthiase »

En Afrique sub-saharienne, l’anémie gestationnelle (AG) est favorisée par de nombreux facteurs dont la contribution relative est mal connue. Malgré l’application de mesures préventives, leur efficacité dans les conditions réelles d’utilisation est mal connue, non plus que l’impact de l’anémie de la mère sur la santé du nouveau-né. Nous avons montré que les parasitoses (paludisme, helminthiases) et les déficits nutritionnels (fer, folates, vitamine B12) constituent les principales causes d’AG, que le traitement préventif intermittent du paludisme (TPI) et le traitement des helminthes intestinaux contribuent à baisser le risque d’AG, essentiellement chez les primgestes. L’effet de la supplémentation en fer, bien que moins perceptible, permettait de limiter la baisse des réserves en fer et donc de l’hémoglobine constatée au cours de la grossesse, notamment chez les multigestes. L’AG à l’inclusion ou à l’accouchement, apparaissait également associée à une diminution du taux d’hémoglobine et un accroissement du risque d’anémie chez le nouveau-né. Le TPI est efficace pour réduire l’impact du paludisme sur le taux d’hémoglobine. Cette efficacité pourrait être optimisée par l’administration d’une 3ème dose qui protégerait la femme contre les infections palustres du dernier trimestre de la grossesse. Compte tenu de l’accroissement des besoins en fer au cours de la grossesse et de la légère baisse du déficit en fer observée à l’accouchement, nous pensons également que la supplémentation en fer contribue à freiner l’aggravation de la carence martiale dans notre population et préconisons qu’elle soit renforcée
In sub-Saharan Africa, gestational anaemia (GA) is caused by many factors, but the relative contributions of these factors remain unclear. Although widely implemented, the effectiveness of GA preventive measures in real conditions is not completely understood, nor is the impact of GA on newborn’s health. We have shown that parasite infestations (malaria, helminth infestations) and nutrient deficiencies (iron, folate, vitamin B12) are the main causes of GA, the intermittent preventive treatment (IPTp) and the antihelmintic treatments contribute to reduce the risk of GA, particularly in primigravidae. The effect of iron supplementation, although less marked, allowed limiting the decline in iron stores and therefore the decrease in haemoglobin levels observed during pregnancy, especially among multigravidae. The GA at inclusion or at delivery also appeared associated with a decrease in haemoglobin and an increased risk of anaemia in newborns at birth. IPTp is effective in reducing the impact of malaria on haemoglobin concentrations. This efficiency could be optimized by administering a third dose that could protect women against malaria infection in the last trimester of pregnancy. Given the increased iron needs during pregnancy and the slight decrease of iron deficiency observed at delivery, we also think that iron supplementation helps to reduce the worsening of iron deficiency in our population and recommend that it be strengthened

La faune helminthique des bovins de l'ituri (haut-zaire), riche de trente especes parasites differentes, participe a la fois des zones tropicales d'afrique de l'est, des regions humides et des zones d'altitude. L'etude de la distribution geographique des helminthes fait apparaitre, pour les trematodes (fasciola gigantica, schistosoma bovis et dicrocoelium hospes), une importante disparite liee a la repartition des mollusques hotes intermediaires. Les nematodes ont, au contraire, une distribution plus homogene. La mesure du parasitisme helminthique des jeunes animaux, met en evidence la chronologie des infestations: toxocara vitulorum et strongyloides papillosus jusqu'a 4 mois, strongles digestifs de 4 a 12 mois, strongles digestifs et fasciola gigantica de 12 a 20 mois. Les variations saisonnieres de l'infestation helminthique sont mises en evidence, pour les strongles digestifs, dans les quatre zones ecologiques etudiees. L'intensite de ces fluctuations reste cependant moderee ce qui explique le faible retentissement de ce parasitisme sur les productions animales. Les variations saisonnieres de l'infestation par f. Gigantica n'apparaissent que dans les sites a saison seche prolongee

Les phénomènes d'immunité parasitaire ont fait l'objet de nombreux travaux. Ceux-ci ont concerné non seulement les modes de résistence de l'hôte aux parasites, mais également les processus qui permettent aux parasites d'échapper aux moyens de défense, immune ou non, de leur hôte. En ce qui concerne les mécanismes de résistance des parasites à l'attaque de l'hôt, plusieurs hypothèses ont été avancées. Dans le cas particulier de Schistosoma mansoni, Smithers et coll. Avaient évoqué un masquage des antigènes du parasite par des antigènes glycolipidiques provenant de l'hôte après avoir observé la présence de lhaptène d Forssman à la surface des parasites adultes prélevés chez la souris. Les schistosomules, formes jeunes du parasite, cultivés en présence de globules rouges, acquièrent simultanément ce glycolipide et une plus grande résistance à l'action léthale en présence de complément de certains des anticorps dirigés contre eux. Nous nous sommes proposés dans ce travail : d'analyser par des méthodes immunocytochimiques les conditions dans lesquelles divers haptènes lipidiques peuvent être acquis puis éliminés par la surface d'un parasite, de rechercher si l'acquisition de els haptènes ou des lipides de structure des membranes naturelles peuvent exercer une influence sur la résistance de ce parasite à ses anticorps léthaux en présence du complément. Notre modèle d'étude a été Schistosoma mansoni et notre modèle de présentation des lipides à ce parasite, des membrans artificielles, liposomes, ou des membranes naturelles

La mortalite et la morbidite liees au paludisme restent un probleme de sante publique majeur. Suite a des etudes trouvant des taux d'immunoglobulines e eleves dans les acces palustres graves, se posait la question du role des infections helminthiques sur l'evolution des acces palustres a p. Falciparum. L'etude de ces interactions a permis de montrer une association dose dependante entre les helminthiases intestinales et protection vis-a-vis du neuropaludisme, de l'insuffisance renale et de l'ictere lies au paludisme. Au cours de l'acces palustre, les patients infectes par des helminthes avaient des concentrations de derives nitres superieures a celle des patients sans helminthes. Chez ces patients, la correlation positive entre derives nitres et ige totales ainsi que la correlation negative entre derives nitres et scd23 soluble suggerait que l'activation du cd23 membranaire par les complexes immuns ige induisait la synthese de no et protegeait ces patients. Par ailleurs on observait que les patients porteurs d'helminthes etaient plus frequemment porteurs de gametocytes et plus frequemment anemiques. Les patients ayant une infection mixte p. Falciparum et p. Vivax etaient plus souvent infectes par ascaris lumbricoides, suggerant que la coexistence d'especes plasmodiales differentes etait facilitee chez ces patients. La tendance lineaire, la presence de modeles animaux, et la persistance de la protection vis-a-vis du neuropaludisme apres des ajustements sur des facteurs de confusion nutritionnels et socio-economiques, suggeraient une possible relation causale. La frequence accrue du portage de gametocytes et des infections mixtes suggerent qu'au cours de l'evolution un equilibre mutualiste entre les deux parasites ; les helminthes protegeant leur hote et par consequent augmentant leurs chances de se reproduire ; et p. Falciparum augmentant ses chances de reproduction grace a la frequence accrue de gametocytes circulants. En pratique se pose la question des interactions entre differents pathogenes chez l'homme en milieu tropical et de celle d'eventuels effets pervers du traitement des helminthiases en zone d'endemie palustre.

Trois especes de nematodes haemonchinae parasitent les ruminants domestiques en mauritanie. Chacune des trois especes a developpe des adaptations pour survivre dans un milieu sub-desertique en mauritanie. Dans tous les cas, la survie au cours de la saison seche est importante (survie au stade adulte et/ou arret du developpement des larves) et pour le parasite des bovins, la conquete de nouveaux hotes est un atout majeur

The research investigated the combined effects of protein deficiency (PD) and a gastrointestinal nematode infection, Heligmosomoides bakeri , on immunopathology and nutritional status in BALB/c mice. The acute phase of a primary infection reduced resting metabolic rate, but PD did not. Early challenge infection led to temporary anorexia and cessation of weight gain in both protein-sufficient (PS) and PD mice.
Among PS mice, a challenge dose of 200 L3 caused more active worm expulsion than infection with 100 L3. Both serum monocyte chemotactic protein-5 and gut fluid leakage were positively correlated with worm expulsion whereas numbers of mucosal mast cells, eosinophils, goblet cells and Paneth cells were unaffected by doses. Among PD mice, worm survival was prolonged and no dose-dependent worm expulsion was observed. In addition, a wide range of Th1 inflammatory cytokines including leptin was elevated in infected PD mice suggesting (1) that PD mice are unable to mount the appropriate Th2 inflammation and (2) that infection in PD mice induces a Th1 inflammation that allows continuing persistence of the parasite.
The shift to Th1 inflammatory responses in PD mice may also explain modifications in mineral distributions in tissues. Despite adequate dietary intakes of minerals in both PD and PS mice, serum iron concentrations were lower after H. bakeri challenge infection. Infection also reduced calcium and iron concentrations as well as the Ca/Zn ratio in the spleen. In contrast, PD resulted in increased iron and calcium concentrations as well as increased Ca/Zn ratio in the spleen and Fe/Zn ratio in the liver, but reduced calcium, zinc, copper and sulfur concentrations, and the Cu/Zn ratio in the liver.
Re-feeding PD mice with a PS diet restored parasite expulsion, regardless of whether the PS diet was provided during the primary or challenge infection. Thus, although PD mice have suppressed Th2 responses and elevated Th1 inflammation, their response to the primary infection is sufficient to ensure that parasite expulsion occurs once protein status is restored.
Together, these studies show that the shift toward Th1 inflammation plays a key role in prolonged parasite survival and mineral redistribution in protein deficient, infected mice.

Les invasions biologiques sont de plus en plus fréquentes, avec des conséquences importantes sur la biodiversité et la santé humaine. Étudier les mécanismes qui les expliquent permet simultanément (i) d’envisager des stratégies efficaces de contrôle et de prévention et (ii) d’étudier divers processus écologiques et évolutifs sur des échelles de temps contemporaines. Plusieurs hypothèses basées sur le parasitisme et l’immunité des hôtes sont proposées pour expliquer le succès des espèces envahissantes. Ainsi, au cours de l’invasion, les hôtes exotiques (1) perdraient leurs parasites naturels (Enemy Release, ER), (2) transfèreraient leurs parasites exotiques aux hôtes natifs (Spill-Over, SO) et/ou (3) amplifieraient les cycles des parasites natifs au sein des hôtes locaux (Spill-Back, SB). En relation avec ces changements dans les interactions hôtes-parasites, l’hypothèse EICA (Evolution of Increased Competitive Ability) prédit une modulation des ressources de l’hôte envahissant via un investissement moins important dans les réponses immunitaires coûteuses (inflammation) au profit de réponses immunitaires beaucoup moins coûteuses (réponses médiées par les anticorps) et de capacités de reproduction et de dispersion des populations sur le front d’invasion. Le but de ma thèse est de tester ces prédictions dans le cadre de deux invasions actuellement en cours au Sénégal : celles du rat noir Rattus rattus et de la souris domestique Mus musculus domesticus, deux espèces envahissantes majeures tant par leurs impacts (économique, sanitaire, écologique) que par leur distribution quasiment mondiale. Mes travaux se basent sur un dispositif d’échantillonnage en populations naturelles et sur le développement d’approches comparatives le long d’un gradient d’invasion pour chacune des deux espèces exotiques. Les patrons de structure (prévalence, abondance, richesse) de deux communautés de parasites (helminthes gastro-intestinaux, bactéries pathogènes) et les profils immunitaires (réponses médiées par les anticorps naturels, inflammation) des rongeurs commensaux exotiques (M. m. domesticus, R. rattus) et/ou natifs (Mastomys spp.) ont été comparés pour des localités situées dans des régions anciennement envahies (depuis plus de 100 ans), récemment envahies (depuis moins de 30 an : front d’invasion), et non envahies. Mes résultats montrent des variations dans la structure des communautés de parasites et les réponses immunitaires des hôtes natifs et exotiques. Les tendances observées, aussi bien pour les communautés de parasites que pour les composantes immunitaires étudiées le long des deux routes d’invasion, attestent de patrons globalement plus complexes qu’attendu sous les hypothèses de départ, suggérant l’existence de relations complexes entre caractéristiques des communautés d’hôtes et de parasites, investissement immunitaire, conditions environnementales et invasions biologiques. Des approches expérimentales doivent être envisagées afin de déterminer les conséquences et les mécanismes sous-jacents aux différents phénomènes observés
Biological invasions are increasingly phenomenon worldwide having deleterious impacts on biodiversity and human health. Studying the mechanisms explaining them allows both (i) to define efficient strategies for controlling and preventing invaders and (ii) to study ecological and evolutionary processes at contemporary scales. Some major hypotheses rely on parasitism and host immunity to explain invasion success. Thus, exotic host populations (1) may benefit of an " Enemy Release " (ER) through impoverishment of their original parasite communities, and may affect native hosts by (2) transferring exotic parasites (Spill-Over, SO) and/or (3) by increasing transmission risk of native parasites (Spill-Back, SB). In turn, according to the refined “Evolution of Increased Competitive Ability” (EICA) theory, invasive populations should experience immune trade-offs by favouring less expensive antibody-mediated responses over costly inflammation, to increase their competitive ability (dispersion, reproduction). The aim of my thesis is to test these predictions along the invasion routes of two commensal exotic species in Senegal, the domestic mouse (Mus musculus domesticus) and the black rat (Rattus rattus). These rodent species are considered to be major invasive species worldwide inducing high economic, sanitary and ecological damages. My research is based on comparative analyses along one invasion route for each invasive species. We focused on gastrointestinal helminths and pathogenic bacteria as parasite communities, and inflammation and natural antibody-mediated responses as immune estimates. Comparisons were performed for invasive and/or native (Mastomys spp.) rodents between localities of long-established invasion (100-200 years ago), recent invasion (10-30 years ago; invasion front), and non-invaded localities. My findings showed variations along both invasion routes in parasite community structure and immune patterns, but in a more complex way than expected under the initial predictions. The heterogeneity of changes observed highlights the existence of particular relations between host and parasite traits, host immune investment, environmental conditions and biological invasions. Further experimental works are needed to assess the consequences and mechanisms underlying the changes observed along both invasion routes

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Janaúba é a denominação popular mais difundida para as espécies do gênero Himatanthus que ocorrem no Estado do Maranhão. A planta é membro da família Apocynaceae, nativa do Brasil e tem ampla distribuição na região Nordeste, com várias indicações de uso popular, que vai desde o tratamento de inflamações uterinas e gastrites até o tratamento de verminoses. Para avaliar o efeito anti-helmíntico de Himatanthus ssp., contemplando os requisitos de eficácia e segurança para fitoterápicos e tendo em vista a crescente demanda por produtos agropecuários livres de resíduos químicos e a ocorrência de cepas de nematódeos resistentes aos quimioterápicos convencionais, o estudo objetivou contribuir com a investigação de tratamentos anti-helmínticos alternativos com possibilidade de uso na redução da verminose ovina. Inicialmente foi realizada a identificação botânica do vegetal, a produção do extrato bruto hidroalcoólico (EBHA), caracterização fitoquímica, ensaios de toxicidade e atividade ovicida in vitro do EBHA de janaúba sobre nematódeos gastrintestinais em ovinos. O vegetal foi classificado como Himatanthus drasticus. O extrato apresentou compostos nitrogenados, glicosídeos e fenólicos e não foi verificada registros de toxicidade. Houve atividade ovicida (p<0,05) in vitro sobre a emergência de larvas de nematódeos gastrintestinais nas concentrações testadas. Essas observações possibilitam a indicação da planta para testes anti-helmínticos em pequenos ruminantes. Prosseguiu-se experimenação in vivo por trinta dias com ovinos naturalmente infectados por nematódeos gastrintestinais, tendo sido avaliado o efeito do EBHA de H. drasticus sobre a redução do OPG e LPG, bem como as implicações de uso do extrato sobre as atividades e funções orgânicas dos animais tratados. Verificou-se redução...
Janauba the common name of Plumeria (Himatanthus Willd), is the most common species of this genus found in Maranhão state. This plant, widely distributed in the Northeastern, belongs to the Apocynaceae family, is native to Brazil and other warm, tropical countries. Its use in popular medicine ranges from uterine inflammation, gastritis to worm treatment. The anthelmintic effect of Himatanthus ssp. is the focus of this study that aimed at evaluating an alternative anthelmintic treatment with potential use to reduce nematode parasites in sheep. Initially, we performed plant botanical identification, crude hydroalcoholic extract production (EBHA), phytochemical characterization, toxicity testing and in vitro ovicidal activity of Janaúba EBHA on gastrointestinal nematodes found in sheep. The plant was classified as Himatanthus drasticus. The extract presented nitrogen compounds and phenolic glycosides, with no record of toxicity. In vitro ovicidal activity (p <0.05) was observed on the emergence of gastrointestinal nematode larvae at the concentrations tested. These results seemed to indicate the plant potential to be used as anthelmintics in small ruminants. Therefore, in vivo tests continued for thirty days with sheep naturally infected with gastrointestinal nematodes. These trials evaluated the effect of H. drasticus EBHA on EPG and LPG, as well as the implications of using the extract on the activities and bodily functions of treated animals. A reduction (p <0.05) of fecal eggs and larvae was observed in the period; however, liver and kidneys were not influenced by the treatment. The janauba can... (Complete abstract click electronic access below)

Гельмінтози – розповсюджене явище. Кожен житель Землі неодноразово хворіє на гельмінтоз. Паразитарні інфекції явище інтернаціональне. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/32373

The context of this work in Pemba was (i) the initial reestablishment of School-Based Treatment (SBT) with praziquantel (PZQ) and albendazole (ALB) for control of urogenital schistosomiasis and soil-transmitted helminths (STH), respectively, and (ii) the subsequent implementation of mass drug administration (MDA) with or without additional snail control or behavioural modification which was aimed at evaluation of the possibility of elimination of schistosomiasis. The prime focus of the work described was to use regular parasitological monitoring to evaluate and compare control strategies with regard to the effects of intervention on transmission or morbidity. Chapters 1 and 2: General Introduction and Material and Methods respectively Chapter 3: Urogenital schistosomiasis. (i) Use of single annual SBT with PZQ: By assessing urine egg output in new-entry standard (Std)-1 children, neither the intensity nor baseline prevalence of 9.5% was lowered over a two year period of intervention. However, prevalences in St-3 children who had received SBT showed lower prevalences than Std-1 children presumably reflecting PZQ-mediated worm reductions. This supports the WHO recommended use of SBT treatment once/year for areas with prevalence < 20% for morbidity control but demonstrates its lack of effect in transmission control. (ii) Use of MDA (twice/year) alone or combined with snail control or behavioural modification:. Testing of Std-3 and Std-4 children in each of 15 shehias allocated to the three different intervention arms revealed an overall reduction in the prevalence of schistosomiasis from 8.3% in 2012 to 5.4% in 2014 (impact:- behavioural control > snail control>MDA). There was a downward trend in the overall mean intensity across all interventions (from 2.71 1.83 1.71) but no consistent reduction in the proportion of heavy infections among the infected children. Recommendations: Integrated interventions are likely to be necessary for interrupting transmission of schistosomiasis and eventually leading to elimination. In poor resource areas, such as Zanzibar, it would be difficult to implement fully integrated control measures and so focusing on PC in areas with high transmission coupled with behavioural changes and strengthening of diagnostic capability of health facilities could be essential. ii Chapter 4: STH. Faecal examination of the Std-1 children, as above, for the eggs of Ascaris lumbricoides, Trichuris trichiura and hookworm, showed a high frequency of polyparasitism. Neither SBT nor intense MDA significantly reduced prevalence of any STH worm in the communities. The worm specific prevalences were slightly reduced overall, most consistently for Trichuris. However, there were no significant changes in intensity of infection, which remained light in the majority of infected children. Recommendations: No impact of either SBT or MDA on transmission to Std-1 children was observed. Integrated approaches e.g. WASH (water, sanitation and hygiene), education and PC are likely to be essential for reduction in transmission. Chapter 5: The efficiency of drug distribution and associated compliance were monitored during the MDA by individual questionnaire and reports from the community drug distributors (CDDs). Overall coverage rate was high (~80%) but variable between the districts (69.3-88.2%). Based on questionnaire, a significant proportion of individuals were non-compliant with the MDA especially regarding PZQ (10.2%) although this did not associate with knowledge about disease transmission, signs/symptoms or risk factors for schistosomiasis. Only mild adverse effects were reported. Recommendations: For any future MDA careful thought needs to be given to understanding the variation in compliance observed across the different areas of Pemba. There is a need of intensifying sensitization meetings in the communities with focus of discussion on potential side effects which may develop. Engage religious and other influential leaders during sensitization meetings. Chapter 6: Since the intensive enhanced MDA for schistosomiasis was aimed at evaluating the possibility of elimination of transmission, the role in transmission of the preschool (> 3 < 5yr) children, who were not previously included in PC in Pemba, was assessed. A substantial proportion of these children was infected (7.04%), the prevalence steadily increasing with age. By questionnaire to mothers/care-givers, contact with stream/pond water through washing and visiting with the children were significant risk factors for pre-school infection. Recommendations: In view of the preschool prevalence demonstrated, the community MDA was extended to < 3yr olds. The government should be ready to register and order paediatric formulation of PZQ once it becomes available. Diagnostic capability of the respective health facilities has to be strengthened in terms of training of laboratory personnel and purchase of essential laboratory equipment. iii Chapter 7: Implementation of snail control in Pemba prompted study of transmission of schistosomiasis by the snail intermediate host, Bulinus spp. Only ~1% of fieldcollected snails shed cercariae but 56% of tested snails were found infected by PCR. DNA sequencing confirmed the presence of B. nasutus and B. globosus, both of which transmitted schistosomes as judged by cercarial shedding and molecular techniques. Recommendations: Further studies are needed to confirm the potential role of the B. nasutus in the transmission of urogenital schistosomiasis in Pemba. For monitoring of schistosomiasis transmission, it would be essential to assess the presence of infection in snail host using molecular techniques especially when elimination is achieved or targeted. Chapter 8: Increasing intensity of PZQ administration raises concerns about possible selection of drug resistance in S. haematobium and prompted studies on the efficacy of PZQ and its effects on parasite genetic diversity in Pemba. It was found that PZQ efficacy was comparable to previous trials. Miracidial samples collected from Std-1 children in 2011 showed diverse, and some novel, haplotypes of the Cox-1 gene of S. haematobium. Clustering of the different haplotypes from different areas indicated the role of internal/external migration in the spread of infection. Recommendations: Praziquantel remains effective and should still be used for the treatment of schistosomiasis at the individual, community or school level in Pemba. More studies are needed to assess susceptibility to PZQ of different S. haematobium haplotypes and of the groups (G1 and G2) with which they associate. Chapter 9: General Discussion: Overall it was concluded that S. haematobium and STH infections remain a public health problem in Pemba and that, although PC using SBT helps control parasite burdens, integrated control measures were more effective and would be required to reduce transmission to approach elimination. Valuable experience in implementation and monitoring of such measures (MDA±snail control/behavioural modification) and application of modern genetic analysis tools was gained during the work and further studies on the snail hosts and population genetics of S. haematobium proposed.

Protein deficiency may increase susceptibility to gastrointestinal (GI) parasitic infections, possibly as a result of impaired systemic and/or intestinal effector responses induced by downregulation of Th2 cytokines and/or upregulation of Th1 cytokines. To test this hypothesis, female BALB/c mice (n = 18/diet) were fed a control (24%), marginal (7%), or deficient (3%) protein diet and given a challenge infection with the GI nematode, Heligmosomoides polygyrus. The 3% mice had higher worm burdens at 1, 2 and 4 weeks post-challenge infection (pci), lower increases in serum IgE, reduced intestinal eosinophilia, and depressed mucosal mast cell proliferation and activation at 1 to 2 weeks pci. To determine whether these suppressed effector responses in the 3% mice were associated with altered spleen and mesenteric lymph node (MLN) cytokine profiles, cells were restimulated in vitro with parasite antigen and cytokine concentrations were measured. Deficient MLN cells secreted significantly less IL-4 and more IFN-gamma at 1--2 weeks pci than did control MLN cells. Deficient spleen cells also secreted more IFN-gamma at 2 weeks pci compared with control spleen cells. From RT-PCR analyses, the 3% mice also had lower IL-4 mRNA expression in spleen and MLN at 1--2 weeks pci. Our study supports the hypothesis that protein deficiency exacerbates the survival of a GI nematode parasite by decreasing IL-4 (Th2) and increasing IFN-gamma (Th1) early in the infection, leading to reduced gut and systemic Th2 effector responses.

Orientador: Jeffrey Frederico Lui
Coorientador: Ana Clara Gomes dos Santos
Banca: Euclides Braga Malheiros
Banca: Leoman Almeida Couto
Banca: Ana Cláudia Ruggieri
Banca: Daniel Praseres Chaves
Resumo: Janaúba é a denominação popular mais difundida para as espécies do gênero Himatanthus que ocorrem no Estado do Maranhão. A planta é membro da família Apocynaceae, nativa do Brasil e tem ampla distribuição na região Nordeste, com várias indicações de uso popular, que vai desde o tratamento de inflamações uterinas e gastrites até o tratamento de verminoses. Para avaliar o efeito anti-helmíntico de Himatanthus ssp., contemplando os requisitos de eficácia e segurança para fitoterápicos e tendo em vista a crescente demanda por produtos agropecuários livres de resíduos químicos e a ocorrência de cepas de nematódeos resistentes aos quimioterápicos convencionais, o estudo objetivou contribuir com a investigação de tratamentos anti-helmínticos alternativos com possibilidade de uso na redução da verminose ovina. Inicialmente foi realizada a identificação botânica do vegetal, a produção do extrato bruto hidroalcoólico (EBHA), caracterização fitoquímica, ensaios de toxicidade e atividade ovicida in vitro do EBHA de janaúba sobre nematódeos gastrintestinais em ovinos. O vegetal foi classificado como Himatanthus drasticus. O extrato apresentou compostos nitrogenados, glicosídeos e fenólicos e não foi verificada registros de toxicidade. Houve atividade ovicida (p<0,05) in vitro sobre a emergência de larvas de nematódeos gastrintestinais nas concentrações testadas. Essas observações possibilitam a indicação da planta para testes anti-helmínticos em pequenos ruminantes. Prosseguiu-se experimenação in vivo por trinta dias com ovinos naturalmente infectados por nematódeos gastrintestinais, tendo sido avaliado o efeito do EBHA de H. drasticus sobre a redução do OPG e LPG, bem como as implicações de uso do extrato sobre as atividades e funções orgânicas dos animais tratados. Verificou-se redução... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Janauba the common name of Plumeria (Himatanthus Willd), is the most common species of this genus found in Maranhão state. This plant, widely distributed in the Northeastern, belongs to the Apocynaceae family, is native to Brazil and other warm, tropical countries. Its use in popular medicine ranges from uterine inflammation, gastritis to worm treatment. The anthelmintic effect of Himatanthus ssp. is the focus of this study that aimed at evaluating an alternative anthelmintic treatment with potential use to reduce nematode parasites in sheep. Initially, we performed plant botanical identification, crude hydroalcoholic extract production (EBHA), phytochemical characterization, toxicity testing and in vitro ovicidal activity of Janaúba EBHA on gastrointestinal nematodes found in sheep. The plant was classified as Himatanthus drasticus. The extract presented nitrogen compounds and phenolic glycosides, with no record of toxicity. In vitro ovicidal activity (p <0.05) was observed on the emergence of gastrointestinal nematode larvae at the concentrations tested. These results seemed to indicate the plant potential to be used as anthelmintics in small ruminants. Therefore, in vivo tests continued for thirty days with sheep naturally infected with gastrointestinal nematodes. These trials evaluated the effect of H. drasticus EBHA on EPG and LPG, as well as the implications of using the extract on the activities and bodily functions of treated animals. A reduction (p <0.05) of fecal eggs and larvae was observed in the period; however, liver and kidneys were not influenced by the treatment. The janauba can... (Complete abstract click electronic access below)
Doutor

The effect of low dietary zinc on the survival and reproduction of an intestinal nematode (Heligmosomoides polygyrus) during both primary (Experiment 1) and challenge (Experiment 2) infections was investigated. Plasma zinc concentrations were significantly lower in mice fed a 5 ppm zinc diet (ZR), compared with control mice fed a 60 ppm zinc diet (C) in both experiments. There were no significant differences between ZR and C mice in any other zinc parameter or on worm burdens or worm fecundity in either experiment. Comparisons between the primary infection and the challenge infection did suggest a possible effect of calorie restriction on worm burdens.
Parasitic infection did, however, affect the host nutritional status. Spleen weight was significantly higher in infected mice in both experiments. In the challenge infection, both liver and spleen copper concentrations were significantly higher, and spleen iron concentration significantly lower in the infected mice. That these significant results were seen only in the challenge infection may suggest the role of the host immune response.

Interactions among zinc deficiency, energy restriction, immunity and Heligmosomoides polygyrus (Nematoda) infection in mice were investigated. Mice were fed zinc-sufficient (Zn+: 60mg zinc/kg diet), zinc-deficient (Zn$-$: 0.75 mg/kg) or pair-fed (PF) diets. Liver and serum zinc concentrations were reduced in Zn$-$ mice, but zinc content of worms was unaffected by host diet. Both zinc deficiency and energy restriction accelerated worm maturation during a primary infection, but zinc deficiency caused stunting of female worms. Energy restriction led to a anteriorad distribution of worms along the intestine whereas zinc deficiency led to a posteriorad distribution. Enhanced parasite survival in Zn$-$ and PF mice was associated with a decreased immune response in both primary and challenge infections. In the primary infection, spleen cell production of interleukin-4 (IL-4) and interferon-gamma (IFN-$ gamma$), peripheral eosinophilia and serum levels of IgE and IgG1 were reduced by zinc deficiency, whereas the reduced delayed type hypersensitivity (DTH) response and impaired interleukin-5 (IL-5) production were attributed to energy restriction. In the challenge infection, reduced antibody levels (total IgE and IgG1, parasite-specific IgG1 and IgG3) and eosinophilia were attributed to zinc deficiency whereas the higher worm numbers were attributed to a combined effect of zinc deficiency and energy restriction. Although the absolute number of spleen cells was reduced in both Zn$-$ and PF mice, neither deficiency altered the proportion of the cell subpopulations. In vitro functional assays in response to parasite antigen (Ag) revealed that T cell proliferation was reduced by a direct effect of zinc deficiency on T cells, and by the effects of energy restriction on antigen presenting cells (APC). Impaired cytokine production in Zn$-$ mice was more complex. Zinc deficiency reduced T cell function (IL-4 production), energy restriction decreased T cell (IFN-$ gamma$ productio

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The recently classified neglected tropical diseases (NTD), -- onchocerciasis, lymphatic filariasis, schistosomiasis, and soil-transmitted helminthiasis -- are all coendemic in Nigeria. The World Health Organization recommended strategy for addressing these diseases is preventive chemotherapy through annual mass drug administration (MDA) with ivermectin, albendazole, and praziquantel. Integrated delivery of these medicines has become the de facto strategy advocated for in the literature as a means of reducing costs through shared resources. Little empirical evidence, however, exists to support this. This paper explores these diseases and the concept of integration in the context of the global strategies for their control. A literature review was conducted using PubMed to identify articles published containing any of the disease names and costs. Of the 2,028 articles returned, only 14 published between 1998 and 2011 met the criteria for review. All costs were adjusted for inflation. Overall, the mean cost of MDA by any means was 0.83 cents. No data comparing separate MDA to integrated MDA were found. To examine this, a model was created comparing MDA programs with similar distribution strategies and targeting similar diseases. Data from separate articles presenting stand alone MDA were combined to give a mean cost of 0.42 cents to deliver two medicines in two rounds. This was compared with articles showing integrated MDA, which gave a mean cost of 0.25 cents to deliver two medicines in a single round. This suggests a cost savings of 40 percent. To verify this, data from a NTD program in Nigeria that transitioned to integrated MDA was examined in detail. In 2008, eight districts received a single round of ivermectin with albendazole followed at least 1 week later by a single round of praziquantel to school-aged children. The following year, a single round of all three drugs was co-administered. The number of treated individuals was essentially unchanged during both years (1,301,864 in 2008 and 1,297,509 in 2009). The total programmatic costs for the MDA, not including drug and overhead costs, reduced by 41% from $123,624 to $72,870, similar to savings seen in the literature review. Cost savings were attributed largely to transportation and personnel costs. Integrated delivery of medicines is recommended for mature programs targeting these diseases.

The objectives of this study were to determine the effect of different types and levels of dietary fiber on Heligmosomoides polygrus (Nematoda) in laboratory mice. BALB/c mice were randomly assigned to one of seven diets: no fiber, cellulose (5%, 10%, 20%), and pectin (5%, 10%, 20) and infected with H. polygyrus one week later. The length of intestine increased significantly with the concentration of pectin and was associated with longer villi, thicker mucosa and increased villus/crypt ratio. In contrast, changing concentration of cellulose had minimal effects on the gastrointestinal tract. More day 5 larvae were found in mice fed 20% pectin, but neither type nor level of dietary fiber affected worm survival or spatial distribution. An increase from 5% to 10% pectin increased per capita egg production both in vivo and in vitro, but a further increase to 20% pectin decreased per capita egg production in vivo to the low level seen in mice fed no fiber. However when the parasites from mice fed 20% pectin diet were cultured in vitro, they released very high numbers of eggs. Changing concentration of cellulose had no effect on parasite egg production in vivo or in vitro. Our study supports the hypothesis that pectin promotes the establishment and reproduction of Heligmosomoides polygyrus, and that this is closely related to the changes in gut morphology. Therefore we conclude that cellulose, not pectin, should be used to balance reduced content of macronutrients in studies on malnutrition and nematode infection.

Both major histocompatibility genes (MHC) and infection have been shown to influence urinary odours in mice, and mice may use MHC-associated odours to detect kin for the purpose of choosing communal nesting partners, or to avoid mating with close relatives. Additionally, mice may use infection-related odours to avoid mating with sick individuals or those genetically susceptible to infection. I tested the above theories using urine as the source of odour. In a series of odour preference experiments, employing two MHC-congenic strains of mice (B10 and B10.Q), I tested the proposition that females prefer MHC-similar female odours when choosing female relatives as nesting partners, and that females prefer MHC-disparate male odours for the purpose of disassoratative mating. I found that females did not display a preference for MHC-similar female odours or MHC-disparate male odours. However, when B10.Q male urine donors were infected with 100 L3 larvae of Heligmosomoides polygyrus (Nematoda), both strains of female displayed a significant preference for the odours of uninfected B10 males. To determine whether female odour preference for uninfected males extended to actual mate choice, I subsequently examined female mate choice in a controlled setting. Using CD-1 outbred mice, I found that females preferred to mate with uninfected males over males subclinically infected with 200 L3 of H. polygyrus , as evidenced by first ejaculation preferences. In this experiment, males were tethered, and as such, male dominance interactions were prevented. Thus, in the final experiment, to assess whether male dominance interactions influenced female mate choice, in addition to infection, I tested female mate choice in a seminatural setting, which allowed for social interactions to occur. In this study, paternity was ascertained through DNA analysis and the resulting data indicated that neither male dominance status nor infection had a substantial impact on fema
Overall, the data do not support the theory that MHC-based preferences occur through urinary odours. However, the results do substantiate previous findings regarding female preferences for the odours of uninfected males. Furthermore, data from the controlled mate choice assay indicate that female odour preference for uninfected males extends to actual mate choice. Conversely, in the seminatural setting neither dominance nor infection prevailed as factors driving female mate choice. I suggest that this may be a consequence of the structural complexity of my arenas.

The influence of energy restriction on the transmission dynamics of a direct life cycle nematode, Heligmosomoides polygyrus, within free-running arena Systems has to date remained unexplored. Indoor populations of CD-1 outbred mice were established for 12 weeks in arenas and fed either energy-suffi ci ent (ES) or energy-restricted (ER-20% réduction in metabolizable energy) diets. Infection was introduced to ail arenas following 3 weeks of diet treatment. Contrary to previous findings, the mice fed the ER diets compensated for the deficiency by increasing food consumption and thus, while early in the experiment energy restriction was evident, dietary effects were no longer observed after 6 weeks. Worm burdens, measured at 4 time points over the course of the experiment, were higher in mice fed the ES diets. Although mice fed the ER diets had greater contact with infected areas, the mice fed the ES diets increased the duration of behaviours that heighten ingestion of the parasite - self and allogrooming. Dietary effects on behaviour were observed only after infection was introduced and were more pronounced in the durations of individual bouts rather than in overall durations or time budgets. Nesting bouts were prolonged in mice in the ER arenas perhaps as a means of thermoregulation to counteract the combined effects of infection and energy restriction. The duration of exploratory bouts was also higher in the ER mice possibly due to an inability to receive or process information in their environment. Social interactions, predominantly involving sniffing, increased after infection was introduced, supporting the rôle of odour in communicating infection status in same-sex conspecifics. Together these results provide a more comprehensive ethogram of mice in a semi-natural setting and highlight those behaviours where adaptive plasticity allows response to dietary and infection stresses.

The aim of this research was to determine the influence of iron deficiency on both the efficacy and metabolic patterns of albendazole in mice infected with Heligmosomoides polygyrus. Anthelmintic efficacy was markedly decreased in iron-deficient mice; the deficiency was also associated with a decrease in body weight, altered hematological parameters and a decreased net egg output; worm establishment in the deficient group was not affected by the deficiency. Although anthelmintic efficacy was significantly decreased by the iron deficiency, plasma concentration profiles of the main metabolites, albendazole sulphoxide and albendazole sulphone, were not changed by the deficiency. Levels of intestinal cytochrome P-450, the main metabolizing enzyme of albendazole however, was significantly depressed in iron-deficient mice. These observations suggest that although pharmacokinetic parameters are not affected by iron deficiency, nutritional status has the potential to influence anthelmintic efficacy and thus warrants further study.

In the past 20 years, boron has been identified as an essential trace element for animals and humans but also as an increasingly important industrial pollutant. We examined first whether boron influenced survival of the gastrointestinal nematode Heligmosomoides bakeri. Female Balb/c mice were fed deficient (0.1 mug B/g), marginal (2.0 mug B/g) or control (12.0 mug B/g) diets, and infected with third-stage larvae. Although liver boron concentrations did not differ among diet groups, dietary boron deficiency impaired survival of the parasite and modulated a broad range of cytokines and chemokines. On the other hand, infection history altered liver mineral concentrations. Second, we examined whether elevated boron concentrations would exert toxic effects on H. bakeri in vitro. Boron toxicity was evidenced by reduced motility, fecundity, infectivity and survival. Feeding stages and free-living stages were more sensitive than non-feeding stages and parasitic stages respectively in a dose-dependent manner.

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FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
Doenças tropicais negligenciadas (DTNs), assim classificadas pela Organização Mundial de Saúde, constituem um grupo de infecções praticamente eliminadas no mundo desenvolvido, mas que persistem em áreas pobres de países de baixa renda. Dentre elas estão a ascaridíase, a tricuríase e a ancilostomíase, cujos agentes etiológicos têm parte de seu ciclo evolutivo passando pelo solo, e são, por isso, denominadas de geohelmintoses. Recentemente, a giardíase também foi incluída como DTN, uma vez que sua forma de transmissão pode ser associada com falta de saneamento. Este estudo transversal de base populacional visou à investigação da ocorrência dessas parasitoses em três municípios do sudeste de Minas Gerais. Para tanto, 2367 indivíduos foram selecionados aleatoriamente. Os dados foram obtidos por meio de um questionário estruturado acerca das condições socioeconômicas, ambientais e culturais da população amostral e do exame de uma única amostra fecal de cada participante, pelo método de sedimentação espontânea (HPJ). Para cada amostra fecal foram examinadas cinco lâminas, e concluiu-se que o exame de três lâminas por amostra expressou a melhor relação custo-benefício para o SUS. A análise dos resultados mostrou que 6,1% (n=145) da população amostral estava infectada com uma ou duas DTNs. Dentre os indivíduos infectados, as prevalências observadas para ancilostomídeos, G. lamblia, T. trichiura e A. lumbricoides foram 47,3%, 27,3%, 16,0% e 9,3%, respectivamente. Na análise bivariada dos dados (p<0,05; IC 95%), o teste do Qui-quadrado de Pearson foi usado para avaliar a força das possíveis associações entre as variáveis independentes e o desfecho. Na análise de regressão logística, quatro variáveis permaneceram estatisticamente significantes, sugerindo serem os possíveis fatores de risco para as DTNs nos municípios: o destino inadequado do esgoto (p<0,001), o hábito de beber água não potável (p<0,001), a falta de instalação sanitária adequada (p=0,015) e pertencer ao sexo masculino (p<0,001). Os resultados encontrados neste estudo nos permitem concluir que DTNs estão presentes mesmo em regiões mais desenvolvidas do Brasil. O número de pessoas parasitadas confirma a área como de baixa endemicidade para geohelmintoses e giardíase em relação a outras regiões do Estado, e justifica estudos que avancem no conhecimento do perfil epidemiológico da região e subsidiem o desenvolvimento de políticas públicas locais.
Neglected tropical diseases (NTDs), so classified by the World Health Organization, are a group of infections that have been eliminated in the developed world, but still persist in poor areas of low-income countries. Among them, ascariasis, trichuriasis, and hookworm infection are soil-transmitted helminthiasis. Recently, and despite its worldwide distribution, giardiasis was also included in the WHO list, due to its way of transmission, which can be associated with lack of sanitation. This population-based cross-sectional survey aimed at investigating the occurrence of such infections in three municipalities of southeastern Minas Gerais state. A total of 2,367 individuals randomly chosen provided one single fecal sample. The baseline data consisted of a questionnaire and parasitological coproscopy using the HPJ method. Five slides were examined from each fecal sample, allowing us to conclude that, regarding this method, the examination of three slides per sample presented a satisfactory sensitivity and the best cost-effectiveness for the SUS. The results showed that 6.1% (n=145) of the population sample was infected with either one or two NTDs, of which the prevalences observed for hookworms, G. lamblia, T. trichiura, and A. lumbricoides were 47.3%, 27.3%, 16.0% e 9.3%, respectively. In the bivariate analysis (p<0.05; CI 95%), Pearson Qui-square tests were used to assess the strength of the associations. Multivariate analysis was run with all significant variables. Four variables remained significant in the logistic regression, as the possible risk factors for the installation and spread of the infections in the municipalities: inadequate sewage discharge (p<0.001), the habit of drinking unsafe water (p<0.001), lack of adequate sanitary infrastructure in the household (p=0.015), and masculine sex of the individual (p<0.001). Our findings allow us to conclude that NTDs occur even in more developed areas of Brazil. Our numbers confirm the study area as low endemic for giardiasis and soil-transmitted helminthiasis, and justify surveys in order to get more information on the epidemiological profile of the Zona da Mata Mineira region, aiming at giving support to the development of local health policies.

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Human toxocariasis is a worldwide parasitic zoonosis, with underestimated prevalence and characterized by complex diagnosis, treatment, and control. These aspects justify the search for new supportive alternatives to control this tissue helminthiasis. In this sense, experimental models have shown the potential of probiotic agents in reducing the intensity of infections with Toxocara canis larvae. Therefore, studying the effect of probiotics in vertical transmission is also relevant, as this type of transmission is essential in definitive hosts and has been shown in humans. This study aims at assessing the effect of Saccharomyces boulardii probiotic on the vertical transmission of Toxocara canis larvae in female mice inoculated during the last third of pregnancy. Two groups of eight female Swiss mice were formed. Females in Group 1 (G1) were fed with ration supplemented with S. boulardii probiotic, and females in G2 (control) were fed with ration without probiotic. The supply of ration for both groups started 15 days before mating, continued during pregnancy and was maintained until the 21st day of lactation. Experimental infection of females was given on day 14 of pregnancy, when 300 T. canis eggs were intragastrically inoculated. Lactating females and infants were euthanized on the 21st day of lactation. After necropsy, organs and skeletal striated muscle (carcass) were submitted to tissue digestion with 1% pepsin and 1% hydrochloric acid. Next, detection and quantification of larvae were performed on the material. Frequency of vertical transmission to the G1 offspring (probiotic) was 21.6% lower than in the G2 (control). In addition, the number of T. canis larvae recovered from G1 female mice offspring (probiotic) was 42.1%, which is significantly lower (p=.026) than the number of larvae recovered from G2 female offspring (control). It can be concluded that there was a beneficial effect of S. boulardii on the studied conditions, resulting in a reduction in the rate of vertical transmission of T. canis and confirming its potential in contributing to the control of visceral toxocariasis.
A toxocaríase humana é uma zoonose parasitária com distribuição mundial, apresenta prevalência subestimada e é caracterizada pela complexidade na realização do diagnóstico, tratamento e controle. Estes aspectos justificam a busca por novas alternativas auxiliares no controle desta helmintíase tecidual. Neste sentido, já foi observado, em modelos experimentais, o potencial de agentes probióticos para a redução da intensidade da infecção por larvas de Toxocara canis. Desse modo, torna-se relevante estudar o efeito dos probióticos também na transmissão vertical, pois este tipo transmissão é fundamental nos hospedeiros definitivos e já foi demonstrada nos seres humanos. O objetivo deste estudo foi avaliar o efeito do probiótico Saccharomyces boulardii sobre a transmissão vertical de larvas de Toxocara canis em camundongos, fêmeas, inoculadas no terço final da gestação. Dois grupos de oito camundongos Swiss, fêmeas, foram formados. As fêmeas do Grupo 1 (G1) foram alimentadas com ração suplementada com probiótico S. boulardii e as fêmeas do G2 (controle) foram alimentadas com ração sem probiótico. O fornecimento de ração para os dois grupos iniciou 15 dias antes do acasalamento, continuou durante toda gestação e foi mantido até o 21° dia de lactação. A infecção experimental das fêmeas ocorreu no 14° dia de gestação, quando foram inoculados, pela via intragástrica, 300 ovos embrionados de T. canis. As fêmeas lactantes e os lactentes foram eutanasiados no 21º dia de lactação. Após a necropsia, órgãos e musculatura estriada esquelética (carcaça) foram submetidos à digestão tecidual com pepsina 1% e ácido clorídrico 1%. A seguir foi realizada a pesquisa e quantificação das larvas no material. A frequência da transmissão vertical para a prole no G1 (probiótico) foi 21,6% menor do que no G2 (controle). Além disso, o número de larvas de T. canis recuperadas, nos lactentes das fêmeas do G1 (probiótico) foi 42,1%, significativamente menor (p=0,026) do que o número de larvas recuperadas na prole das fêmeas do G2 (controle). Conclui-se que houve efeito benéfico do probiótico S. boulardii nas condições estudadas, com a redução na taxa de transmissão vertical de T. canis, confirmando o seu potencial em contribuir para o controle da toxocaríase visceral.

This thesis examines the cost-effectiveness of multi-parasite control strategies of the Soil Transmitted Helminthiasis program in the Philippines, identifying strategy option that gives the best value for money. It establishes the optimal parasite control strategy in terms of frequency and mode of delivery, and whether this varies subnationally. The results of this research using decision-modeling approach are expected to guide the country’s health policy and decision-makers to efficiently allocate scarce health resources and come up with a solid basis for a parasite control policy in the Philippines.

Les invasions biologiques sont de plus en plus fréquentes, avec des conséquences importantes sur la biodiversité et la santé humaine. Étudier les mécanismes qui les expliquent permet simultanément (i) d’envisager des stratégies efficaces de contrôle et de prévention et (ii) d’étudier divers processus écologiques et évolutifs sur des échelles de temps contemporaines. Plusieurs hypothèses basées sur le parasitisme et l’immunité des hôtes sont proposées pour expliquer le succès des espèces envahissantes. Ainsi, au cours de l’invasion, les hôtes exotiques (1) perdraient leurs parasites naturels (Enemy Release, ER), (2) transfèreraient leurs parasites exotiques aux hôtes natifs (Spill-Over, SO) et/ou (3) amplifieraient les cycles des parasites natifs au sein des hôtes locaux (Spill-Back, SB). En relation avec ces changements dans les interactions hôtes-parasites, l’hypothèse EICA (Evolution of Increased Competitive Ability) prédit une modulation des ressources de l’hôte envahissant via un investissement moins important dans les réponses immunitaires coûteuses (inflammation) au profit de réponses immunitaires beaucoup moins coûteuses (réponses médiées par les anticorps) et de capacités de reproduction et de dispersion des populations sur le front d’invasion. Le but de ma thèse est de tester ces prédictions dans le cadre de deux invasions actuellement en cours au Sénégal : celles du rat noir Rattus rattus et de la souris domestique Mus musculus domesticus, deux espèces envahissantes majeures tant par leurs impacts (économique, sanitaire, écologique) que par leur distribution quasiment mondiale. Mes travaux se basent sur un dispositif d’échantillonnage en populations naturelles et sur le développement d’approches comparatives le long d’un gradient d’invasion pour chacune des deux espèces exotiques. Les patrons de structure (prévalence, abondance, richesse) de deux communautés de parasites (helminthes gastro-intestinaux, bactéries pathogènes) et les profils immunitaires (réponses médiées par les anticorps naturels, inflammation) des rongeurs commensaux exotiques (M. m. domesticus, R. rattus) et/ou natifs (Mastomys spp.) ont été comparés pour des localités situées dans des régions anciennement envahies (depuis plus de 100 ans), récemment envahies (depuis moins de 30 an : front d’invasion), et non envahies. Mes résultats montrent des variations dans la structure des communautés de parasites et les réponses immunitaires des hôtes natifs et exotiques. Les tendances observées, aussi bien pour les communautés de parasites que pour les composantes immunitaires étudiées le long des deux routes d’invasion, attestent de patrons globalement plus complexes qu’attendu sous les hypothèses de départ, suggérant l’existence de relations complexes entre caractéristiques des communautés d’hôtes et de parasites, investissement immunitaire, conditions environnementales et invasions biologiques. Des approches expérimentales doivent être envisagées afin de déterminer les conséquences et les mécanismes sous-jacents aux différents phénomènes observés
Biological invasions are increasingly phenomenon worldwide having deleterious impacts on biodiversity and human health. Studying the mechanisms explaining them allows both (i) to define efficient strategies for controlling and preventing invaders and (ii) to study ecological and evolutionary processes at contemporary scales. Some major hypotheses rely on parasitism and host immunity to explain invasion success. Thus, exotic host populations (1) may benefit of an " Enemy Release " (ER) through impoverishment of their original parasite communities, and may affect native hosts by (2) transferring exotic parasites (Spill-Over, SO) and/or (3) by increasing transmission risk of native parasites (Spill-Back, SB). In turn, according to the refined “Evolution of Increased Competitive Ability” (EICA) theory, invasive populations should experience immune trade-offs by favouring less expensive antibody-mediated responses over costly inflammation, to increase their competitive ability (dispersion, reproduction). The aim of my thesis is to test these predictions along the invasion routes of two commensal exotic species in Senegal, the domestic mouse (Mus musculus domesticus) and the black rat (Rattus rattus). These rodent species are considered to be major invasive species worldwide inducing high economic, sanitary and ecological damages. My research is based on comparative analyses along one invasion route for each invasive species. We focused on gastrointestinal helminths and pathogenic bacteria as parasite communities, and inflammation and natural antibody-mediated responses as immune estimates. Comparisons were performed for invasive and/or native (Mastomys spp.) rodents between localities of long-established invasion (100-200 years ago), recent invasion (10-30 years ago; invasion front), and non-invaded localities. My findings showed variations along both invasion routes in parasite community structure and immune patterns, but in a more complex way than expected under the initial predictions. The heterogeneity of changes observed highlights the existence of particular relations between host and parasite traits, host immune investment, environmental conditions and biological invasions. Further experimental works are needed to assess the consequences and mechanisms underlying the changes observed along both invasion routes

As helmintoses gastrintestinais estão entre as principais enfermidades na criação de ovinos, sendo importante causa de mortalidade e de redução na produtividade dos animais. O controle das infecções por nematódeos é baseado no uso de drogas anti-helmínticas, porém com a descrição emergente de parasitos resistentes, a eficácia deste tratamento tem diminuído. Portanto, métodos alternativos de controle são necessários para a diminuição ou, até mesmo, a substituição do uso de drogas para o controle das verminoses em pequenos ruminantes. O uso dos taninos condensados (TC) no controle das helmintoses gastrintestinais de ovinos em todo o mundo tem se mostrado promissor. Este trabalho teve como objetivo avaliar o efeito anti-helmíntico dos TC sobre nematódeos gastrintestinais de ovinos. Durante o período de testes foram realizados quatro ensaios experimentais: ensaio A avaliação in vitro da ingestão por larvas de primeiro estágio (L1) de Haemonchus contortus, Trichostrongylus colubriformis e Teladorsagia circumcincta, para avaliar o efeito anti-helmíntico dos TC provenientes do extrato de acácia (Acacia mearnsii); ensaio B estudo sobre a infecção natural dos cordeiros a campo, animais infectados com H. contortus e T. colubriformis, sendo os mesmos divididos em dois grupos (tratados com extrato de acácia e não tratados); ensaios C e D realizados com infecção experimental dos animais por nematódeos gastrintestinais (H. contortus e T. colubriformis, respectivamente). Nos dois últimos ensaios, os animais foram divididos em cinco grupos, sendo: GI (controle infectado com nematódeo); GII (recebeu sorgo taninífero); GIII (recebeu extrato de acácia uma vez ao dia); GIV (recebeu extrato de acácia duas vezes ao dia) e GV (controle não infectado). Os resultados dos ensaios A (ingestão larval) e B (infecção natural) foram promissores e demonstraram o efeito direto dos TC sobre os nematódeos parasitas de ovinos, com diferença significativa (P < 0,05) entre os grupos. Observando-se os resultados do experimento com infecção experimental por H. contortus (ensaio C), não se detectou diferença estatística entre os grupos (P > 0,05), porém no experimento com infecção por T. colubriformis (ensaio D) foi evidenciada diferença (P < 0,01) nos valores de OPG entre os grupos tratados com sorgo (GI) e extrato de acácia por dois dias (GIV), quando comparados ao controle infectado (GI); sendo também evidenciada quando da comparação do número de fêmeas de helmintos do GI e GIV (P < 0,01). Redução na viabilidade dos ovos de helmintos (estágio de ovo até L1) e no número de larvas infectantes isoladas de coproculturas provenientes dos grupos tratados com TC foram evidentes nos ensaios C e D. Os resultados foram promissores demonstrando a ação direta dos TC sobre nematódeos gastrintestinais de ovinos e principalmente sobre a produção de larvas infectantes; porém mais estudos são necessários para a indicação de um controle de parasitos gastrintestinais baseado no uso de fontes de TC
Gastrointestinal nematodes are a major cause of economic loss in farm animals. Gastrointestinal parasite control programs based on chemotherapy are failing because of increased anthelmintic resistance; thus, alternative controls strategies are necessary to reduce the use of anthelmintic drug in animal production have been studied. Condensed tannins (CT) have shown potential for alternative control of gastrointestinal nematodes in sheep. The main objective of the present study was to investigate the anthelmintic effect of condensed tannin on sheep gastrointestinal nematodes. During the experimental period four experiments were carried out: Experiment A in vitro study of larval feed inhibition (first stage larvae-L1) of Haemonchus contortus, Trichostrongylus colubriformis and Teladorsagia circumcincta, to evaluate the anthelmintic effect of CT from acacia (Acacia mearnsii) condensed tannins extract (CTE); Experiment B study of the potential uses of CTE to control gastrointestinal parasites in sheep naturally infected with H. contortus e T. colubriformis, with animals divided into two groups (drenched and undrenched with CTE); Experiments C and D were carried out with sheep experimentally infected with gastrointestinal nematodes (H. contortus e T. colubriformis, respectively). In these experiments (C and D) the animals were divided into five groups GI (nematodes infect control); GII (supplemented with taniniferous sorghum); GIII (drenched with CTE once); GIV (drenched with CTE for two days) and GV (non-infect control). The results of experiment A (larval feed inhibition) and B (natural nematode infection) were promissory and showed the direct effect of CT on sheep gastrointestinal nematodes with significant difference (P < 0.05) between groups. The results of H. contortus experimental infections (experiment C) did not provide significant difference between groups (P > 0.05), however the T. colubriformis experimental infection results (experiment D) showed significant difference (P < 0.01) on EPG values of sheep supplemented with sorghum (GI) and drenched with CTE for two days (GIV), when compared with infect control (GI); Significant reduction of female worm burden was demonstrated between GI and GIV (P < 0.01) on experiment D. Reduction on nematode egg viability (from eggs to L1) and infective larvae (L3) from coprocultures made with faeces from CT treated groups were observed in experiments C and D. The results evidenced the direct action of CT on sheep gastrointestinal nematodes and mainly on L3 production; however more studies are necessary to indicate a strategic alternative parasite control based in CT sources

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Schistosomiasis and geo-helminthiasis are parasitic diseases considered as a serious public health problem, both related to poverty, lack of adequate sanitation and hygiene. The municipality of Malhador-SE join the campaign against geo-helminths and S. mansoni since 2013 and is engaged in the Program of Control of Schistosomiasis aiming the elimination of schistosomiasis and the reduction of the parasitic burden of geo-helminths. The purpose of this study was to compare the prevalences of S. mansoni and geo-helminths and socio-environmental conditions in schoolchildren in the municipality of Malhador / SE. An epidemiological, descriptive and cross - sectional study was carried out. The sampling took place in February 2016. The study involved schoolchildren between 5 and 14 years in two municipal schools located in an urban school (Pacheco School) and another in the rural area (Barrocão School). The prevalence of children with S. mansoni and / or geo-helminths was determined using the Kato-Katz method, and compared to the socio-environmental conditions of the students. The positive cases found in the communities were georeferenced with the aid of a GPS receiver and to analyze and visualize the pattern of the distribution and density of the cases the kernel estimator was applied. Of the 337 fecal samples collected, 48.7% resulted in positive samples. The prevalence of infection was 17.6% for S. mansoni, 23.7% for A. lumbricoides, 4% for T. trichiura and 0.4% for E. vermicularis in the urban area (Pacheco School). On the other hand, in the rural area (Barrocão School) were 55.9% for S. mansoni and 28.8% for A. lumbricoides. The highest frequency of S. mansoni was found in the rural area and in male children, whereas the cases of geo-helminths had similar prevalence in both zones. In the rural area, the parasitic burden prevailed in mild (87.9%) and moderate (12.1%) and in urban areas, mild (65.3%), moderate (28.6%) and severe (6.1%). Regarding the environmental and sanitary conditions, the children in the rural area had more "contact with water" (90.5%), being associated with the occurrence of S. mansoni in the demographic areas (p = 0.0394). Likewise, the variables "sanitary installation, waste disposal, water supply and waste destination" also showed an association between the "occurrence of S. mansoni and geo-helminths" (p <0.001). Of the hygiene habits, 100% of rural schoolchildren consume untreated water (p <0.001). The analysis of the spatial distribution of the positive cases of S. mansoni and geo-helminths allowed us to visualize that in the urban area the specialization was revealed homogeneously, whereas in the rural zone it was heterogeneous and that through the Kernel estimator, the agglomeration of these cases is located in the west of Malhador in the urban and rural areas are located to the west and east of the municipality. The present study showed that Malhador is a municipality endemic to S. mansoni and that inadequate sanitary and hygiene conditions favored a high prevalence of parasitic diseases in the schoolchildren of the localities.
A esquistossomose e as geo-helmintíases são doenças parasitárias consideradas como um grave problema de saúde pública, ambas, relacionadas com a pobreza, a falta de saneamento adequado e de higiene. O município de Malhador-SE participa da campanha contra geo-helmintos e S mansoni desde 2013 e trabalha com o Programa de Controle da Esquistossomose com o objetivo de alcançar a meta de eliminação da esquistossomose e redução da carga parasitária de geo-helmintos. O objetivo desse estudo foi analisar, comparativamente, as prevalências de S. mansoni e geo-helmintos e condições sócio-ambientais em escolares do município de Malhador/SE. Foi realizado um estudo epidemiológico, descritivo e de corte transversal. A obtenção das amostras ocorreu no período de fevereiro a junho de 2016. O estudo envolveu escolares entre 5 e 14 anos em duas escolas municipais localizadas uma na zona urbana (Escola Pacheco) e outra na zona rural (Escola Barrocão). Foram identificadas as prevalências de crianças com S. mansoni e/ou geo-helmintos através do método Kato-Katz, e comparadas às condições sócio-ambientais dos escolares. Os casos positivos encontrados nas comunidades foram georreferenciados com o auxílio de um receptor GPS e para analisar e visualizar o padrão da distribuição e densidade dos casos foi aplicado o estimador de Kernel. Das 337 amostras de fezes coletadas, 48,7% resultou em positivas. As prevalências de infecção foram de 17,6% para S. mansoni, 23,7% para A. lumbricoides, 4% para T. trichiura e 0,4% para E. vermiculares na zona urbana (escola Pacheco), enquanto que, na área rural (escola Barrocão) foram de 55,9% para S. mansoni e 28,8% para A. lumbricoides. A maior frequência de S. mansoni foi encontrada na zona rural e em crianças do gênero masculino, enquanto que os casos de geo-helmintos tiveram prevalências semelhantes em ambas as zonas. Na zona rural prevaleceram as cargas parasitárias leve (87,9%) e moderada (12,1%) e na urbana, prevaleceram a leve (65,3%), moderada (28,6%) e grave (6,1%). Em relação às condições ambientais e sanitárias as crianças da zona rural tiveram maior “contato com água” (90,5%) estando associado com a ocorrência de S. mansoni nas áreas demográficas (p=0,0394). Da mesma forma, as variáveis “instalação sanitária, destino dos dejetos, abastecimento de água e destino do lixo” também mostraram associação entre a “ocorrência de S. mansoni e geo-helmintos” (p<0,001). Dos hábitos de higiene, 100% dos escolares da área rural consomem água não tratada (p<0,001). A análise da distribuição espacial dos casos positivos de S. mansoni e geo-helmintos permitiu visualizar que na área urbana a espacialização foi revelada de forma homogênea, enquanto que na zona rural apresentou-se heterogênea e que através do estimador de Kernel, a aglomeração desses casos está localizada a oeste de Malhador na zona urbana e na rural estão localizados a oeste e a leste do município. O atual estudo mostrou que Malhador é um município endêmico para S. mansoni e que as condições sanitárias e de higiene inadequadas favoreceram a elevada prevalência das parasitoses nos escolares das localidades.

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The viability of a formulation of the fungus Monacrosporium thaumasium (Drechsler, 1937) was evaluated for the biological control of bovine gastrointestinal nematode parasites. Two groups of seven female calves each, holstein x zebu crossbred, four to six months of age, were placed in Cynodon dactylon pastures. In group A, each animal received 20g of pellets of M. thaumasium orally twice a week during a four-month period that began with the onset of the rainy season (October, 2001). In group B (control), the calves did not receive any fungal treatment. The counts of eggs per gram of faeces (EPG) for anima1s of the group B were significantly greater (P< 0.05) than those for animaIs of the group A and the difference of the EPG between the animals of group A and B at the end of the study period was 88,8%. The nematodes of the Cooperia genus were the most prevalent in the both pastures. It is concluded that use of this dose and periodicity of application of M. thaumasium pellets were efficient in the control of bovine gastrointestinal nematode parasites.
A viabilidade de uma formulação do fungo Monacrosporium thaumasium (Drechsler, 1937) foi avaliada no controle biológico de nematóides parasitos gastrintestinais de bovinos. Dois grupos de sete bezerras cada, mestiças holandês x zebu, de quatro a seis meses de idade, foram colocados em pastagens de Cynodon dactylon. No grupo A, cada animal recebeu 20 g de péletes (formulação granulada) de M. thaumasium via oral, duas vezes por semana, durante quatro meses, com início na estação chuvosa (outubro de 2001). No grupo B (controle), os bezerros não receberam nenhum tratamento fúngico. As contagens de ovos por grama de fezes (OPG) dos animais e das larvas infectantes encontradas na pastagem do grupo B foram significativamente maiores (P< 0,05) do que as dos animais do grupo A, e a diferença entre o OPG dos animais do grupo A e o do grupo B, no final do experimento, foi de 88,8%. Os nematóides do gênero Cooperia foram os mais prevalentes em ambas as pastagens. Concluiu-se que a aplicação de péletes de M. thaumasium na dosagem e periodicidade de aplicação usadas foi eficiente no controle de nematóides parasitos gastrintestinais de bovinos.

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Introdução: a prevalência de doenças alérgicas tem aumentado no mundo, particularmente nas populações urbanas de países em desenvolvimento. Objetivos: determinar a prevalência de asma e doenças alérgicas, identificar fatores de risco a elas associados, avaliar a relação entre asma e helmintíase, assim como a relação entre a cicatriz vacinal do BCG e sensibilização atópica em escolares ribeirinhos de Ilhas da Amazônia. Métodos: estudo transversal em 400 escolares (5 a 8 anos) cujos pais responderam os questionários escritos (padrão e complementar) do International Study of Asma and Allergies in Childhood, entre 2007 e 2009. As crianças também foram avaliadas quanto a: medição da cicatriz vacinal do BCG, coletas de fezes (parasitológico) e sangue para dosagem de IgE total e específica séricas. Foram utilizados testes não paramétricos e os fatores de risco foram identificados por regressão logística (stepwise forward) tendo-se como nível de significância 5%. Resultados: prevalência de asma atual e rinoconjuntivite atual foram significantemente maiores entre as crianças vivendo na ilha de Outeiro do que nas da Ilha do Combú (30,5% X 16,5%; 18% x 6%, respectivamente). Nas duas ilhas, ter relato de asma ou rinite nos pais, ter antecedentes pessoais de rinite e tosse noturna no último ano estiveram associados à maior expressão de asma. A regressão logística identificou os riscos de ter asma: na ilha do Combú foram antecedente familiar de asma, ter gato na atualidade e tosse noturna no último ano. Na do Outeiro foram: antecedente familiar de asma, antecedente pessoal de eczema, ter dois ou mais irmãos mais velhos e tosse noturna no último ano. Conjuntamente para as duas ilhas os riscos foram: tosse noturna no último ano e antecedente familiar de asma. Não houve diferença significante entre parasitados e não por helmintos em relação à expressão da asma, exceto ter diagnóstico médico de asma, mais frequente entre as crianças parasitadas. Níveis séricos de IgE total e de IgE específica a A.lumbricoides foram mais elevados nas crianças parasitadas. Correlação entre os níveis séricos de IgE sérica total e as específicas aos alérgenos mostrou significância para Periplaneta americana e A.lumbricoides entre os parasitados e entre os não parasitados foi com B.germanica e B.tropicalis. Correlação entre o diâmetro médio da pápula induzida pelos aerolérgenos e o nível de IgE sérica específica para D.pteronyssinus e B.tropicalis foi significante entre os não parasitados. Diâmetro médio da cicatriz vacinal do BCG das crianças com asma não diferiu das sem. Não houve correlação significante entre os níveis séricos de IgE total e específica e o diâmetro médio da cicatriz vacinal do BCG. Conclusões: houve variação na prevalência de asma e rinite entre as ilhas, sendo mais elevada na do Outeiro, que possui características de zona urbana. Os fatores de risco de ter asma foram diferentes para as duas ilhas refletindo as características individuais de cada ilha e conjuntamente foi o antecedente familiar de asma, enfatizando a participação da genética como importante fator de risco. Os helmintos não foram associados à expressão da asma nem da sensibilização alérgica. É importante criar medidas preventivas mais apropriadas contra o desenvolvimento de asma para cada uma das ilhas. Mais estudos são necessários para clarificar o papel dos helmintos sobre a asma e doenças alérgicas.
Background: epidemiological studies have focused on possible association between helminth infection and the development of asthma and/or allergies. Objectives: to evaluate the association between helminth infection and asthma and its relation to serum levels of total and specific IgE for A. lumbricoides and aeroallergens, besides evaluating possible relation between BCG scar and allergic sensitization. Methods: cross sectional study in 400 schoolchildren from two Amazon Islands. A standardized written questionnaire (asthma module) from International Study of Asthma, Allergies in Childhood protocol was administered and asthmatic children were those with current wheezing. The following procedures were done: skin prick test (positive test with papule mean diameter > 3mm); blood samples for assessment of serum levels of total and specific IgE for A. lumbricoides and aeroallergens (positive those with levels > 0.36 kU/L); feces samples for helminths examination (positive = infected with at least one helminth); mean diameter of BCG vaccine scar measurement. Analyses were assessed for both islands together and non-parametric tests were applied obtaining 5% of significance level. Results: there was no significant difference between infected and non-infected children with helminths related to asthma expression, save for having physician-diagnosed asthma that was more frequent in helminths infected children. Serum levels of total and specific IgE for A. lumbricoides were higher in infected children. Significant correlations between serum levels of total and specific IgE for aeroallergens to Periplaneta americana and Ascaris lumbricoides among those infected and among those non-infected was for B. germanica e B. tropicalis. Significant correlation between papule mean diameter and serum level of specific IgE for D. pteronyssinus e B. tropicalis among those not infected. Mean diameter of BCG vaccine wasn´t different among children with asthma and those without, as well as there was no correlation between serum levels of total and specific IgE. Conclusions: parasite infections are not associated with either asthma expression or to allergic sensitization, but positive association was verified between physician-diagnosed asthma and helminth infection. More studies are necessary to clarify helminth infection role on asthma and allergic diseases.
TEDE
BV UNIFESP: Teses e dissertações

Submitted in fulfillment of the requirements for the degree of Doctor of Technology: Health Sciences, Durban University of Technology, Durban, South Africa, 2018.
Soil-transmitted helminths are a major health concern, especially in tropical and sub-tropical regions. Poor sanitation and poverty are major pre-disposing factors contributing to increase in infections. Infection with STH is mainly through exposure to water, soil and food contaminated with the eggs of these parasites. Accurate detection and quantification of STH eggs in environmental samples is therefore critical for the determination of infection risks from exposure. Accurate detection of these eggs is also important in the adoption of risk reduction strategies. This thesis presents the development of a revised method for the accurate detection and quantification of STH eggs in different environmental matrices, such as wastewater, sludge etc. It further presents the application of this method in the comparative determination of STH egg reduction efficiencies of centralized wastewater treatment plants and decentralized wastewater treatment (DEWATS) plants in Durban, South Africa and Maseru, Lesotho. The concentration of viable STH eggs in dried sludge from Durban, South Africa and Dakar, Senegal was also determined and compared with both WHO guidelines and South African national standards for sludge reuse. The risks of infection with STHs for different populations exposed (directly and indirectly) to wastewater, wastewater contaminated surface water and sludge were determined using both quantitative microbial risks assessment and epidemiological approaches. Despite the plethora of methods available for the detection and quantification of STH eggs in the environment there is no internationally accepted method, however the most commonly used methods are based on the principles of sedimentation, differential flotation and microscopy. These are mainly adaptations of the WHO and USEPA methods. These methods were found to be similar with a few differences which affected the recovery rates reported. However, the major challenges with the conventional methods are the time needed for sample analysis and the use of reagents that could possibly affect the recovery of viable STH eggs. A new revised method was developed based on review of literature and laboratory experiments. In this method the heterogeneity of environmental samples was accounted for by the development of different pre-processing steps, involving the use of detergents to aid in the separation of eggs from particles in samples such as sludge, UD waste and untreated wastewater. Additionally, the use of sieves of different pore sizes ensured that the number of debris on the microscope slides was reduced considerably. The use of these sieves also reduced the time need for sample analysis, due to the elimination of the spontaneous sedimentation step, which is commonly used. This spontaneous sedimentation step takes between 12-24 hours therefore prolonging the time needed for sample analysis. Reagents such as acetoacetic acid and ethyl acetate were found to result in considerable loss of egg viability after just 5 minutes of exposure. This new method therefore does not involve their usage. The elimination of the use of acetoacetic acid and ethyl acetate step also reduces the number of steps involved in sample analysis. This reduces room for error as well as helping in fast analysis of samples. In addition to a much faster sample analysis the method has recovery percentages of 80.25% to 97.63% in sludge and wastewater samples respectively, with sensitivity of 2-3 eggs per liter in wastewater samples and 5-7 eggs per 20 gram of sludge. Exposure to STH eggs in the environment is mainly through wastewater, either treated or untreated, this exposure could therefore be eliminated through wastewater treatment. Centralized wastewater treatment systems are the most favored treatment options globally. These centralized treatment systems incur high cost of construction, maintenance and operations which may hamper the robustness in developing countries and rural areas. One of the most widely used alternative means of wastewater treatment is the anaerobic baffled reactors (ABRs) and planted gravel filters (PGFs) (collectively referred to as DEWATS in this thesis), which have been considered as low cost, effective wastewater treatment options. However, there is lack of comparative assessment of the STH egg removal efficiency of these two different wastewater treatment approaches. Eggs of Ascaris spp, hookworm, Trichuris spp, Taenia spp and Toxocara spp were the commonly recorded STH eggs in the untreated wastewater at the inlets of the centralized wastewater treatment plants as well as the DEWATS plants (except for Toxocara spp). There was variation in STH egg concentrations between and within the study areas, indicating difference in STH infections among the populations both in Durban and Maseru. STH egg removal varied between and within the different wastewater treatment plants as well. The DEWATS plants achieved 95-100% STH egg removals as compared to the 67 to 100% in the centralized wastewater treatment plants. This could be attributed to the difference in treatment processes. Among the different STHs, reduction in Ascaris spp eggs was significantly higher, irrespective of the type of treatment, which is attributed to the high relative density of the egg resulting in a higher settling velocity than the other STH eggs. Reduction or elimination of STH eggs through wastewater treatment is achieved by removing the eggs from the wastewater into the sludge. STH egg concentration in sludge is therefore mostly higher than in the wastewater. Sludge from Durban and Dakar after 60 days of drying under ambient environmental conditions contained very high concentration of viable STH eggs. Ascaris spp, hookworm, Trichuris spp, Taenia spp and Toxocara spp were the commonly recorded STH eggs, except for Dakar were Taenia spp and Toxocara spp were not detected in the sludge. STH egg concentrations were higher in Dakar than in Durban, with viable STH egg concentrations exceeding both the USEPA regulatory value (≤0.25 eggs/g TS) and the WHO guideline value (≤1 eggs/g TS). This variation in egg concentration could be attributed to the difference in prevalence and intensity of STH infections in the two study areas. Over a ten-month study period concentration of viable eggs in the sludge from Durban varied considerably, probably influenced by the environmental conditions. A decay rate of 0.0056 per day was calculated for egg die-off during drying. The rate of decay is low therefore drying alone cannot produce sludge meeting both local and international standards and guidelines for sludge reuse. Determination of STH infection risks due to exposure to wastewater and sludge either directly or indirectly is critical in the prevention of infection. Exposure to the effluents during wastewater irrigation is one major route of infection. STH egg concentrations in the final effluents from the centralized and DEWATS wastewater treatment plants were consistently higher than the WHO recommended guideline for unrestricted agricultural use (≤ 1 helminth egg/L), whereby the direct reuse of the effluents for agriculture was found to pose a higher risk than the WHO tolerable risk of infection (1 ×10-2 pppy) for farmers and consumers. Annually the use of effluents from the DEWATS plants poses the least risk of infection (1.9 ×10-2 (±2.4×10-4)), which is marginally higher than the WHO tolerable risk value. Well maintained DEWATS plants are more efficient in removing or reducing the concentration of STH eggs in wastewater and therefore pose the least risks of infection compared to centralized wastewater treatment plants. Consumers of vegetables from these farms are also at considerable risks of STH infections. Probabilistic assessment of the STH infection risks showed that farmers applying sludge from Durban and Dakar without adequate protective measures had risks of infections higher than the WHO tolerable risks figure (1×10-2 pppy). Based on the estimated risks of infection after decay, exposure to farm soil after 40-50 days of sludge application may reduce the risks of infection to levels lower the WHO tolerable risks value. However, this may not be practical due to the need for farmers to attend to their crops frequently. Incorporation of the decay of the eggs into the risks assessment also indicated that, using lettuce as a representative vegetable, harvesting of vegetables in Dakar could be done after 40 days of sludge application to reduce the risks of infection to the WHO tolerable value but in Durban harvesting after 30 days ensures that consumers are protected. Therefore, to protect both the farmers and consumers exposed to STH eggs through wastewater/sludge reuse in agriculture the implementation of the WHO multi-barrier approach to risk reduction is required. Risks of STH infections could be directly estimated using epidemiological approaches. By using this approach, the concept of STH infection risks for farmers using wastewater was assessed through direct measurements of the concentration of STHs both in wastewater used for irrigation and the farm soil, as well as the actual load of STHs ova in the stool of farmers and their family members. In Kumasi, Ghana, wastewater used for irrigation of vegetables and the farm soil contained high concentration of STH eggs. There was positive correlation between STH concentrations in the wastewater/soil and STH eggs load in stool of the exposed farmers. Stool analysis after 3 months, following deworming, showed a fast re-infection rate. Farmers exposed to the wastewater were three times more likely as compared to the control group of non-farmers to be infected with Ascaris spp (OR = 3.9, 95% CI, 1.15-13.86) and hookworm (OR = 3.07, 95% CI, 0.87-10.82). These risks of infection were higher in the rainy season than the dry season. This corresponds to a higher egg concentration in wastewater used for irrigation during this period. This indicates a relationship between STH infection and egg concertation in the environment. This study therefore contributes to the evidence-based conclusion that wastewater irrigation contributes to a higher incidence of STHs infection for farmers. In conclusion, this thesis therefore presents a new revised method that can be used to determine the STH egg concentration in different environmental samples. The development of this method also provides an opportunity to comparatively assess the STH egg reduction/removal efficiency of the more commonly used centralized wastewater treatment plants and DEWATS plants. The accurate quantification of viable STH eggs provide inputs for the probabilistic assessment of STH infection risks for different populations exposed to effluents from these two wastewater treatment approaches. This assessment of risks provides a public health perspective to the wastewater treatment. Additionally, it was concluded with the used of this method that drying of sludge for 60 days in Durban or Dakar does not produce sludge of good quality for agricultural application. This was confirmed by the estimates of STH infection risks determined using quantitative microbial risks assessment. This thesis therefore shows the importance of accurate quantification of STH eggs in the determination of infection risks either though QMRA or epidemiological approache
D

M.Tech.
Capra hircus (boer goats) are well known for their hardy adaptability to arid regions and their ability to survive and thrive in areas where grazing is low in nutrition. They are an irreplaceable source of protein for the lower income groups of arid regions in South Africa. Boer goats are prone to helminthiasis (infestation of intestinal parasitic worms), which can result in poor health (Kumba, 2002). This can have a significant effect on the long term productivity of the animal (Alexandre and Mandonnet, 2005), resulting in economic and nutritional strain in poor farming communities who depend on goats as a primary source of protein and income (Kumba, 2002). Conventional treatments worldwide show a trend of resistance of helminths to treatment and carry the risk of inducing side effects when administered (Kumba, 2002; Scarfe, 2004; Schnyder et al., 2005). Homoeopathic research has shown promising results in the treatment of helminthiasis in animals (Zacherias et al., 2008; Jeannes et al, 2001), but no research currently exists of homoeopathy on helminthiasis in Boer goats.

Approximately two billion people are infected with helminths worldwide. In order to develop a vaccine against these pathogens, more needs to be known about the immune response to helminths. Eosinophils are important for resistance to some helminth species and their recruitment to infected tissues, attachment to parasites and degranulation may all be critical processes for immunity. Complement may contribute to these processes via generation of chemotactic factors (C3a and C5a) or opsonisation of the parasite with C3b/iC3b. The importance of complement during helminth infection is unclear, though complement does promote leukocyte-mediated killing of several helminth species in vitro. The aim of the present study was to investigate the role of complement in immunity of mice to Nippostrongylus brasiliensis, with a focus on whether complement facilitates eosinophildependent resistance to this parasite. A new fluorescence-based method for quantifying in vitro complement deposition and leukocyte adherence on N. brasiliensis was developed. C3 from human serum was deposited on infective-stage L3 via the classical or lectin complement pathways. In contrast, the alternative complement pathway mediated binding of mouse C3 and eosinophil-rich mouse peritoneal leukocytes to L3. Interestingly, the ability of complement and leukocytes to bind to the parasite changed as it matured. Larvae recovered from the skin 30 min post-injection (p.i.) were coated with C3, however those harvested 150 min p.i. exhibited reduced C3 binding capacity. Binding of C3 and eosinophils to larvae recovered from the lungs 24-48 h p.i. (L4) was also diminished compared to that seen on L3. Adult intestinal worms bound C3 and leukocytes only when treated ex vivo with serum and cells. Mice lacking in classical (C1q-deficient), alternative (factor B-deficient) or all complement pathways (C3-deficient) were then employed to determine if complement was important for resistance of mice to N. brasiliensis. IL-5 Tg mice deficient in individual complement genes were generated to assess whether complement contributed to eosinophildependent resistance to the parasite. Factor B deficient mice exhibited impaired C3 deposition on larvae, eosinophil recruitment, eosinophil degranulation and larval aggregation in the skin 30 min p.i. Eosinophil recruitment was similarly abolished by treatment of mice with the C5aR inhibitor PMX53. However at 150 min p.i., larval aggregation, eosinophil and neutrophil recruitment, leukocyte adherence and eosinophil degranulation were largely complement-independent. Ablation of factor B or C3 caused minor but significant increases in lung-larval burden during primary, but not in secondary, infections. Critically, a lack of C3 or factor B in IL-5 Tg mice failed to greatly impair the strong innate anti-parasite resistance typical of these animals, suggesting that eosinophils can provide immunity to N. brasiliensis infection in the absence of complement. This was unexpected, given the evidence from this and previous studies which suggested that in vitro, complement is important for promoting eosinophil-dependent killing of N. brasiliensis and other helminth species. The mechanism(s) by which eosinophils kill N. brasiliensis remain unknown, but may involve the coordination of the complement system with complement-independent factors that act in the early stages of infection. Critically, the influence of complement is limited, because soon after entry into the host, the parasite develops the ability to resist complement activation.
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Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2008