Journal articles: 'Rickettsiosi'

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Ugleva, S. V., and S. V. Shabalina. "Ricketsioses in the Lower Volga region." Journal of microbiology, epidemiology and immunobiology 98, no. 2 (May 5, 2021): 231–38. http://dx.doi.org/10.36233/0372-9311-60.

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The aim of this work was to describe the features of the epidemiology and clinic of rickettsioses at the Lower Volga region.Materials and methods. Scientific papers on searchable electronic databases (Web of Science, PubMed, eLIBRARY and ResearchGate) were selected and analyzed. Of the 256 found sources, the authors selected 87, taking into account the keywords, after an analysis of the selected literature, 30 sources were included in the present study in accordance with the topic of the work.Results. On the territory of the Lower Volga region, including the Astrakhan region, two rickettsioses are recorded: rickettsiosis from the tick-borne spotted fevers group — Astrakhan spotted fever (APL) and Q fever (coxiellosis). APL is a relatively new rickettsiosis common in the Caspian Sea basin, along the floodplain of the river Volga to Volgograd, capturing the steppes of Kalmykia. Q fever is recorded in many countries of the world, and in Russia, in terms of its importance and distribution, it occupies one of the first places among endemic diseases. The clinical characteristics of these rickettsioses are also presented.Conclusions. The study of the epidemiology and clinic of rickettsial infections remains relevant.

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Martínez-Caballero, A., B. Moreno, C. González, G. Martínez, M. Adames, J. V. Pachar, J. B. Varela-Petrucelli, et al. "Descriptions of two new cases of Rocky Mountain spotted fever in Panama, and coincident infection with Rickettsia rickettsii in Rhipicephalus sanguineus s.l. in an urban locality of Panama City, Panama." Epidemiology and Infection 146, no. 7 (April 5, 2018): 875–78. http://dx.doi.org/10.1017/s0950268818000730.

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AbstractThe clinical and pathologic characterisation of two fatal cases of tick-borne rickettsiosis in rural (El Valle) and urban (City of Panama) Panama are described. Clinical and autopsy findings were non-specific, but the molecular analysis was used to identify Rickettsia rickettsii in both cases. No ticks were collected in El Valle, while in the urban case, R. rickettsii was detected in Rhipicephalus sanguineus s.l., representing the first molecular finding in this tick in Panama and Central America.

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Nogueras, María Mercedes, Beatriz Roson, Sergio Lario, Isabel Sanfeliu, Immaculada Pons, Esperança Anton, Aurora Casanovas, and Ferran Segura. "Coinfection with “Rickettsia sibirica subsp. mongolotimonae” and Rickettsia conorii in a Human Patient: a Challenge for Molecular Diagnosis Tools." Journal of Clinical Microbiology 53, no. 9 (July 1, 2015): 3057–62. http://dx.doi.org/10.1128/jcm.00457-15.

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Rickettsioses are zoonoses transmitted by vectors. More than one agent can coexist in vectors. Although vectors may transmit more than one microorganism to humans, information on dual infections is scarce. We present a case of a patient with an atypical rickettsiosis diagnosis in whom two species ofRickettsiawere detected.

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Gafarova, M. T., E. I. Bondarenko, K. D. Maliy, E. E. Alieva, I. L. Evstafiev, N. N. Tovpinec, N. K. Malaya, and A. V. Kubyshkin. "Prevalence of causative agents of transmissive tick-borned ricketsious in the Crimean peninsula." Russian Clinical Laboratory Diagnostics 67, no. 3 (March 25, 2022): 170–76. http://dx.doi.org/10.51620/0869-2084-2022-67-3-170-176.

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The paper presents the results of a study of the prevalence of Ixodid ticks - potential carriers of tick-borne rickettsiosis pathogens. Ectoparasites were collected in various natural and climatic zones of the Crimean Peninsula within the year 2016-2018. As a result of screening with the help of real-time PCR analysis (PCR-RT), a genetic marker (a section of the gltA gene) of the rickettsia group of tick-borne spotted fever was detected in ticks. The most common DNA marker of rickettsia was found in ticks in the eastern regions of the steppe zone - 50,6 %, in the north-western part of the steppe zone this value was 12,0 %. The least amount of rickettsia target DNA was detected in ticks collected in the mountain forest and south bank zones - 4,5 %. As a result of sequencing of positive DNA samples from fragments of the gltA, ompA, ompB, and sca4 genes, the species composition of rickettsias was established. The DNA of 8 species of rickettsia was identified: Circulation of three R. conorii, R. massiliae, R. sibirica subsp. mongolotimonae, R. slovaca, R. aeschlimannii, R. monacensis, R. helvetica, R. raoultii. R. massiliae, R. slovaca, and R. helvetica were established in the Crimean Peninsula for the first time. The peculiarities of the geographical distribution of the identified rickettsia species were determined, which was due to the spread of mites-carriers of pathogens. The revealed diversity of rickettsia species and their vectors, due to the isolation of the areas of the main feeding animals and the established routes of migratory birds, suggests the circulation of other rickettsia species on the territory of the Crimean Peninsula. The obtained results suggest that the diseases of tick-borne rickettsiosis in the Crimean Peninsula can be caused not only by R. conorii, as previously thought, but also by other types of rickettsii.

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Conti-Díaz, Ismael A., Jonas Moraes-Filho, Richard C. Pacheco, and Marcelo B. Labruna. "Serological evidence of Rickettsia parkeri as the etiological agent of rickettsiosis in Uruguay." Revista do Instituto de Medicina Tropical de São Paulo 51, no. 6 (December 2009): 337–39. http://dx.doi.org/10.1590/s0036-46652009000600005.

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We report three new rickettsiosis human cases in Uruguay. The three clinical cases presented clinical manifestations similar to previous reported cases of Rickettsia parkeri in the United States; that is mild fever (< 40 ºC), malaise, headache, rash, inoculation eschar at the tick bite site, regional lymphadenopathy, and no lethality. Serological antibody-absorption tests with purified antigens of R. parkeri and Rickettsia rickettsii, associated with immunofluorescence assay indicated that the patients in two cases were infected by R. parkeri. Epidemiological and clinical evidences, coupled with our serological analysis, suggest that R. parkeri is the etiological agent of human cases of spotted fever in Uruguay, a disease that has been recognized in that country as cutaneous-ganglionar rickettsiosis.

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Lang, Susanne, Tobias Bergmann, Diana-Maria Kuschel, and Helmut Schiffl. "Komplizierte Zeckenstich-Rickettsiose nach Safari-Tour in Südafrika." DMW - Deutsche Medizinische Wochenschrift 143, no. 15 (July 30, 2018): 1116–19. http://dx.doi.org/10.1055/a-0622-7606.

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Zusammenfassung Anamnese und klinischer Befund Ein 41-jähriger, bis dato gesunder Mann zog sich während einer Safaritour im Krüger Nationalpark einen Zeckenstich zu. 5 Tage später bekam er hohes Fieber mit schwerem Krankheitsgefühl. An der Zeckenstichstelle entwickelte sich ein charakteristisches Ulkus mit schwärzlichem Grund, Schorfbildung und rotem Hof (Eschar, Tache noir). Reise -und Zeckenstichanamnese legten den Verdacht einer Rickettsiose nahe. Untersuchungen und Diagnose Die Diagnose einer Rickettsiose aus der Zeckenstichfiebergruppe (spotted-fever-group) wurde serologisch bestätigt. Der klinische Verlauf der Rickettsiose wurde durch eine Myokarditis kompliziert, die zunächst nur durch ein erhöhtes Troponin-I auffiel und später mittels Kardio-MRT bestätigt wurde. Der komplizierte Verlauf und der singuläre Eschar sprechen für eine Infektion mit Rickettsia conorii. Therapie und Verlauf Es kam es zu einer raschen Rückbildung der Symptome der febrilen Infektionserkrankung unter der Therapie mit Doxycyclin. Die Rekonvaleszenz der importierten Reisekrankheit war durch die Myokarditis verzögert. Folgerung Rickettsiosen sollten bei Afrikareisenden differenzialdiagnostisch in Erwägung gezogen werden. Sie verlaufen in der Regel mild; komplizierte Verläufe können auch bei gesunden jungen Menschen auftreten.

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Raoult, D., and V. Roux. "Rickettsioses as paradigms of new or emerging infectious diseases." Clinical Microbiology Reviews 10, no. 4 (October 1997): 694–719. http://dx.doi.org/10.1128/cmr.10.4.694.

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Rickettsioses are caused by species of Rickettsia, a genus comprising organisms characterized by their strictly intracellular location and their association with arthropods. Rickettsia species are difficult to cultivate in vitro and exhibit strong serological cross-reactions with each other. These technical difficulties long prohibited a detailed study of the rickettsiae, and it is only following the recent introduction of novel laboratory methods that progress in this field has been possible. In this review, we discuss the impact that these practical innovations have had on the study of rickettsiae. Prior to 1986, only eight rickettsioses were clinically recognized; however, in the last 10 years, an additional six have been discovered. We describe the different steps that resulted in the description of each new rickettsiosis and discuss the influence of factors as diverse as physicians' curiosity and the adoption of molecular biology-based identification in helping to recognize these new infections. We also assess the pathogenic potential of rickettsial strains that to date have been associated only with arthropods, and we discuss diseases of unknown etiology that may be rickettsioses.

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Narra, Hema P., Abha Sahni, Krishna Mohan Sepuru, Jessica Alsing, and Sanjeev K. Sahni. "Sensing the Messenger: Potential Roles of Cyclic-di-GMP in Rickettsial Pathogenesis." International Journal of Molecular Sciences 23, no. 7 (March 31, 2022): 3853. http://dx.doi.org/10.3390/ijms23073853.

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Pathogenic bacteria causing human rickettsioses, transmitted in nature by arthropod vectors, primarily infect vascular endothelial cells lining the blood vessels, resulting in ‘endothelial activation’ and onset of innate immune responses. Nucleotide second messengers are long presumed to be the stimulators of type I interferons, of which bacterial cyclic-di-GMP (c-di-GMP) has been implicated in multiple signaling pathways governing communication with other bacteria and host cells, yet its importance in the context of rickettsial interactions with the host has not been investigated. Here, we report that all rickettsial genomes encode a putative diguanylate cyclase pleD, responsible for the synthesis of c-di-GMP. In silico analysis suggests that although the domain architecture of PleD is apparently well-conserved among different rickettsiae, the protein composition and sequences likely vary. Interestingly, cloning and sequencing of the pleD gene from virulent (Sheila Smith) and avirulent (Iowa) strains of R. rickettsii reveals a nonsynonymous substitution, resulting in an amino acid change (methionine to isoleucine) at position 236. Additionally, a previously reported 5-bp insertion in the genomic sequence coding for pleD (NCBI accession: NC_009882) was not present in the sequence of our cloned pleD from R. rickettsii strain Sheila Smith. In vitro infection of HMECs with R. rickettsii (Sheila Smith), but not R. rickettsii (Iowa), resulted in dynamic changes in the levels of pleD up to 24 h post-infection. These findings thus provide the first evidence for the potentially important role(s) of c-di-GMP in the determination of host-cell responses to pathogenic rickettsiae. Further studies into molecular mechanisms through which rickettsial c-di-GMP might regulate pathogen virulence and host responses should uncover the contributions of this versatile bacterial second messenger in disease pathogenesis and immunity to human rickettsioses.

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Stanley, Hannah M., Shelby L. Ford, Alyssa N. Snellgrove, Kris Hartzer, Emily B. Smith, Inna Krapiunaya, and Michael L. Levin. "The Ability of the Invasive Asian Longhorned Tick Haemaphysalis longicornis (Acari: Ixodidae) to Acquire and Transmit Rickettsia rickettsii (Rickettsiales: Rickettsiaceae), the Agent of Rocky Mountain Spotted Fever, Under Laboratory Conditions." Journal of Medical Entomology 57, no. 5 (April 27, 2020): 1635–39. http://dx.doi.org/10.1093/jme/tjaa076.

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Abstract The invasive Asian longhorned tick, Haemaphysalis longicornis Neumann, was first detected in the United States in 2017. It has since been found in 12 states, and there is concern that the tick’s parthenogenetic ability and wide variety of host species may allow for broader dissemination. Of the tick-borne diseases endemic to the United States, Rocky Mountain spotted fever (RMSF), a rapidly progressive and potentially fatal disease caused by Rickettsia rickettsii, is the most severe. There is considerable geographical overlap between spotted fever rickettsioses cases, which include RMSF, and the currently known distribution of H. longicornis, providing the potential for this tick to encounter this pathogen. We have evaluated the ability of H. longicornis to acquire and transmit R. rickettsii under laboratory conditions. Haemaphysalis longicornis as larvae and nymphs acquired the pathogen while feeding on infected guinea pigs. The infection persisted through every life stage, all of which were able to transmit R. rickettsii to naïve hosts. The pathogen was also transmitted at a low frequency between generations of H. longicornis through the ova. While H. longicornis was demonstrated to be a competent vector for R. rickettsii under laboratory conditions, the probability of its involvement in the maintenance and transmission of this pathogen in nature, as well as its potential impact on human health, requires further study.

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Kristof, M. Nathan, Paige E. Allen, Lane D. Yutzy, Brandon Thibodaux, Christopher D. Paddock, and Juan J. Martinez. "Significant Growth by Rickettsia Species within Human Macrophage-Like Cells Is a Phenotype Correlated with the Ability to Cause Disease in Mammals." Pathogens 10, no. 2 (February 19, 2021): 228. http://dx.doi.org/10.3390/pathogens10020228.

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Rickettsia are significant sources of tick-borne diseases in humans worldwide. In North America, two species in the spotted fever group of Rickettsia have been conclusively associated with disease of humans: Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever, and Rickettsia parkeri, the cause of R. parkeri rickettsiosis. Previous work in our lab demonstrated non-endothelial parasitism by another pathogenic SFG Rickettsia species, Rickettsia conorii, within THP-1-derived macrophages, and we have hypothesized that this growth characteristic may be an underappreciated aspect of rickettsial pathogenesis in mammalian hosts. In this work, we demonstrated that multiple other recognized human pathogenic species of Rickettsia, including R. rickettsii, R. parkeri, Rickettsia africae, and Rickettsiaakari can grow within target endothelial cells as well as within PMA-differentiated THP-1 cells. In contrast, Rickettsia bellii, a Rickettsia species not associated with disease of humans, and R. rickettsii strain Iowa, an avirulent derivative of pathogenic R. rickettsii, could invade both cell types but proliferate only within endothelial cells. Further analysis revealed that similar to previous studies on R. conorii, other recognized pathogenic Rickettsia species could grow within the cytosol of THP-1-derived macrophages and avoided localization with two different markers of lysosomal compartments; LAMP-2 and cathepsin D. R. bellii, on the other hand, demonstrated significant co-localization with lysosomal compartments. Collectively, these findings suggest that the ability of pathogenic rickettsial species to establish a niche within macrophage-like cells could be an important factor in their ability to cause disease in mammals. These findings also suggest that analysis of growth within mammalian phagocytic cells may be useful to predict the pathogenic potential of newly isolated and identified Rickettsia species.

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Fortes, Fernanda S., Leonilda C. Santos, Zalmir S. Cubas, Ivan R. Barros-Filho, Alexander W. Biondo, Iara Silveira, Marcelo B. Labruna, and Marcelo B. Molento. "Anti-Rickettsia spp. antibodies in free-ranging and captive capybaras from southern Brazil." Pesquisa Veterinária Brasileira 31, no. 11 (November 2011): 1014–18. http://dx.doi.org/10.1590/s0100-736x2011001100013.

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Capybaras (Hydrochaeris hydrochaeris) are among the main hosts of Amblyomma spp. ticks, which is able to transmit Rickettsia species to human beings and animals. Since they are often infested with potential vector ticks, capybaras may be used as sentinels for rickettsiosis, such as the Brazilian Spotted Fever. The aim of the present study was to determine the prevalence of antibodies against Rickettsia spp. using the indirect immunofluorescence assay (IFA) in 21 free-ranging and 10 captive animals from the Zoological Park of the 'Bela Vista Biological Sanctuary' (BVBS), Itaipu Binational, Foz do Iguaçu, Southern Brazil. Antigens of six rickettsial species already identified in Brazil (Rickettsia rickettsii, R. parkeri, R. bellii, R. rhipicephali, R. amblyommii and R. felis) were used for IFA. Ticks from each capybara were collected for posterior taxonomic identification. A total of 19 (61.3%) samples reacted to at least one of tested species. Seropositivity was found in 14 (45.2%), 12 (38.7%), 5 (16.1%), 4 (12.9%), 3 (9.7%) and 3 (9.7%) animals for R. rickettsii, R. bellii, R. parkeri, R. amblyommii, R. felis and R. rhipicephali, respectively. Two captive capybaras presented suggestive titers of R. rickettsii infection and one sample showed homologous reaction to R. parkeri. Only one free-ranging capybara presented evidence R. bellii infection. Ticks collected on capybaras were identified as Amblyomma dubitatum e Amblyomma sp. Results evidenced the rickettsial circulation in the area, suggesting a potential role of capybaras on bacterial life cycle.

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Batista, Fernanda Gonçalves, Daniella Matos da Silva, Kerriel Thandile Green, Louise Boulsfield de Lorenzi Tezza, Sâmara Pereira de Vasconcelos, Suelen Graziele Soares de Carvalho, Iara Silveira, et al. "Serological survey of Rickettsia sp. in horses and dogs in an non-endemic area in Brazil." Revista Brasileira de Parasitologia Veterinária 19, no. 4 (December 2010): 205–9. http://dx.doi.org/10.1590/s1984-29612010000400003.

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Brazilian Spotted Fever (BSF) is a lethal rickettsiosis in humans caused by the bacteria Rickettsia rickettsii, and is endemic in some areas of Brazil. Horses and dogs are part of the disease's life cycle and they may also serve as sentinel animals in epidemiological studies. The first human BSF case in the State of Paraná was reported in 2005. The present study was conducted in the municipality of Almirante Tamandaré, where no previous case of BSF was reported. Serum samples were collected from 71 horses and 20 dogs from nine properties in the area. Ticks were also collected from these animals. All farmers completed a questionnaire about their knowledge of BSF and animal health management. Serum samples were analyzed by indirect immunofluorescent-antibody assay (IFA) using R. rickettsii and R. parkeri as antigens. Ticks were analyzed by PCR for Rickettsia sp., and all of them were PCR-negative. Six horses (8.45%) and 4 dogs (20%) were identified as seropositive. Farmers were not aware of the correlation between the presence of ticks and risk of BSF. Although a non-endemic area, Almirante Tamandaré is a vulnerable environment for BSF and effective tick control measures are required.

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Campos, Sabrina D. E., Nathalie C. da Cunha, Camila S. C. Machado, Tatiana V. T. de Souza, Ana Beatriz M. Fonseca, Adriano Pinter, Adivaldo H. da Fonseca, and Nádia R. P. Almosny. "Circulação de Rickettsias do Grupo da Febre Maculosa em cães no entorno de Unidades de Conservação Federais do estado do Rio de Janeiro: evidência sorológica e fatores associados." Pesquisa Veterinária Brasileira 37, no. 11 (November 2017): 1307–12. http://dx.doi.org/10.1590/s0100-736x2017001100018.

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RESUMO: Doenças causadas por rickettsias tem ampla distribuição geográfica e estão associadas a artrópodes hematófagos. Rickettsia rickettsii é espécie mais patogênica do Grupo da Febre Maculosa (GFM) e responsável pela Febre Maculosa Brasileira. No sudeste do país a doença é endêmica e inquéritos sorológicos tem demonstrado presença de anticorpos para antígenos do GFM em cães, reforçando a participação do cão como sentinela. Os principais vetores são carrapatos do gênero Amblyomma, cujos hospedeiros são, muitas vezes, animais de vida silvestre. Assim, objetivou-se avaliar a circulação de rickettsias do GFM no entorno de Unidades de Conservação (UC) no Rio de Janeiro por meio da Imunofluorescência Indireta em cães, além de determinar os fatores associados. Amostras de soro de 155 cães foram testadas, sendo 16,1% dos animais sororreagentes pelo menos a um dos antígenos testados. Houve associação entre a sororreatividade dos cães e o acesso à mata; falta de assistência médico-veterinária; falta de medidas contra carrapatos; e renda familiar do responsável de até dois salários mínimos. Cães com este perfil apresentaram maior chance de serem expostos aos agentes do GFM. De acordo com o modelo de regressão logística, não frequentar áreas de mata foi considerado um fator de proteção para o cão, juntamente com possuir acompanhamento médico-veterinário e receber medidas contra carrapatos. Concluiu-se que patógenos do GFM circulam no entorno das UC estudadas, sendo possível que R. rickettsii e R. parkeri infectem cães, uma vez que os animais demonstraram exposição aos dois agentes. Ressalta-se a participação do veterinário e a adoção de medidas de combate a carrapatos como ferramentas na prevenção da infecção rickettsial.

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Rydkina, Elena, Loel C. Turpin, and Sanjeev K. Sahni. "Rickettsia rickettsii Infection of Human Macrovascular and Microvascular Endothelial Cells Reveals Activation of Both Common and Cell Type-Specific Host Response Mechanisms." Infection and Immunity 78, no. 6 (April 12, 2010): 2599–606. http://dx.doi.org/10.1128/iai.01335-09.

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ABSTRACT Although inflammation and altered barrier functions of the vasculature, due predominantly to the infection of endothelial cell lining of small and medium-sized blood vessels, represent salient pathological features of human rickettsioses, the interactions between pathogenic rickettsiae and microvascular endothelial cells remain poorly understood. We have investigated the activation of nuclear transcription factor-kappa B (NF-κB) and p38 mitogen-activated protein (MAP) kinase, expression of heme oxygenase 1 (HO-1) and cyclooxygenase 2 (COX-2), and secretion of chemokines and prostaglandins after Rickettsia rickettsii infection of human cerebral, dermal, and pulmonary microvascular endothelial cells in comparison with pulmonary artery cells of macrovascular origin. NF-κB and p38 kinase activation and increased HO-1 mRNA expression were clearly evident in all cell types, along with relatively similar susceptibility to R. rickettsii infection in vitro but considerable variations in the intensities/kinetics of the aforementioned host responses. As expected, the overall activation profiles of macrovascular endothelial cells derived from human pulmonary artery and umbilical vein were nearly identical. Interestingly, cerebral endothelial cells displayed a marked refractoriness in chemokine production and secretion, while all other cell types secreted various levels of interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) in response to infection. A unique feature of all microvascular endothelial cells was the lack of induced COX-2 expression and resultant inability to secrete prostaglandin E2 after R. rickettsii infection. Comparative evaluation thus yields the first experimental evidence for the activation of both common and unique cell type-specific host response mechanisms in macrovascular and microvascular endothelial cells infected with R. rickettsii, a prototypical species known to cause Rocky Mountain spotted fever in humans.

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Turebekov, Nurkeldi, Karlygash Abdiyeva, Ravilya Yegemberdiyeva, Andrey Kuznetsov, Andrey Dmitrovskiy, Lyazzat Yeraliyeva, Zhanna Shapiyeva, et al. "Occurrence of Anti-Rickettsia spp. Antibodies in Hospitalized Patients with Undifferentiated Febrile Illness in the Southern Region of Kazakhstan." American Journal of Tropical Medicine and Hygiene 104, no. 6 (June 2, 2021): 2000–2008. http://dx.doi.org/10.4269/ajtmh.20-0388.

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Abstract.Undifferentiated febrile illness still represents a demanding medical problem all over the world, but primarily in low- and middle-income countries. Scientific and clinical investigations related to undifferentiated febrile illness and rickettsial diseases in Kazakhstan are lacking. This study reflects the investigation of antibodies against spotted fever group (SFG) and typhus group (TG) rickettsiae in patients with undifferentiated febrile illness in the southern region of Kazakhstan (Almaty and Kyzylorda oblasts). Paired serum samples were gathered from 13 hospitals in these two oblasts and explored for the presence of IgM and IgG antibodies against typhus group and IgG antibodies against spotted fever group rickettsiae using ELISA. Patient’s questionnaires were statistically analyzed. In total, 802 inpatients from Almaty (N = 9) and Kyzylorda (N = 4) hospitals were included in this research. Based on ELISA results, 250 patients out of 802 (31.2%) from both oblasts had IgG antibodies against SFG rickettsiae. Results from 11 (1.4%) patients indicated acute infection with tick-borne rickettsiosis. Regarding TG rickettsiae (R. typhi), a past infection was detected in 248 (30.9%) febrile patients and acute infection in 22 (2.7%) patients in the two selected oblasts. The data indicated that SFG and TG rickettsioses are present in Kazakhstan. Kazakh physicians should be aware of these emerging diseases in both investigated oblasts because the occurrence of these diseases is not suspected during day-to-day clinical practice. The identification of rickettsial pathogens and implementation of modern laboratory methods for the diagnostics of rickettsioses are in need throughout Kazakhstan.

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Schlinsog, Anne-Sophie, Burkhard Kreft, and Wolfgang Marsch. "Rickettsiose." DMW - Deutsche Medizinische Wochenschrift 141, no. 05 (March 3, 2016): 343–45. http://dx.doi.org/10.1055/s-0041-105935.

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Berbis, P. "Rickettsiosis." EMC - Dermatología 41, no. 2 (January 2007): 1–11. http://dx.doi.org/10.1016/s1761-2896(07)70366-7.

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Lagier, J. C., B. Doudier, and P. Parola. "Rickettsiosis." EMC - Tratado de Medicina 13, no. 3 (January 2009): 1–6. http://dx.doi.org/10.1016/s1636-5410(09)70540-9.

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SZABÓ, M. P. J., F. A. NIERI-BASTOS, M. G. SPOLIDORIO, T. F. MARTINS, A. M. BARBIERI, and M. B. LABRUNA. "In vitroisolation fromAmblyomma ovale(Acari: Ixodidae) and ecological aspects of the Atlantic rainforestRickettsia, the causative agent of a novel spotted fever rickettsiosis in Brazil." Parasitology 140, no. 6 (January 30, 2013): 719–28. http://dx.doi.org/10.1017/s0031182012002065.

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SUMMARYRecently, a novel human rickettsiosis, namely Atlantic rainforest spotted fever, was described in Brazil. We herein report results of a survey led around the index case in an Atlantic rainforest reserve in Peruibe municipality, southeastern Brazil. ARickettsia parkeri-like agent (Rickettsiasp. Atlantic rainforest genotype) andRicketsia belliiwere isolated from adultAmblyomma ovaleticks collected from dogs. Molecular evidence of infection with strain Atlantic rainforest was obtained for 30 (12·9%) of 232A. ovaleadult ticks collected from dogs. As many as 88·6% of the 35 examined dogs had anti-Rickettsiaantibodies, with endpoint titres at their highest toR. parkeri. High correlation among antibody titres in dogs,A. ovaleinfestations, and access to rainforest was observed.Amblyomma ovalesubadults were found predominantly on a rodent species (Euryoryzomys russatus). From 17E. russatustested, 6 (35·3%) displayed anti-Rickettsiaantibodies, with endpoint titres highest toR. parkeri. It is concluded that Atlantic rainforest genotype circulates in this Atlantic rainforest area at relatively high levels. Dogs get infected when bitten byA. ovaleticks in the forest, and carry infected ticks to households. The role ofE. russatusas an amplifier host ofRickettsiatoA. ovaleticks deserves investigation.

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Dzul-Rosado, Karla, Luis Donis-Maturano, Juan Arias-León, Jesús Machado-Contreras, Guillermo Valencia-Pacheco, Candi Panti-Balam, Javier Balam-Romero, et al. "Rickettsia Vaccine Candidate pVAX1-OmpB24 Stimulates TCD4+INF-γ+ and TCD8+INF-γ+ Lymphocytes in Autologous Co-Culture of Human Cells." Vaccines 11, no. 1 (January 13, 2023): 173. http://dx.doi.org/10.3390/vaccines11010173.

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Background: In recent years, promising vaccination strategies against rickettsiosis have been described in experimental animal models and human cells. OmpB is considered an immunodominant antigen that is recognized by T and B cells. The aim of this study was to identify TCD4+INF-γ+ and TCD8+INF-γ+ lymphocytes in an autologous system with macrophages transfected with the vaccine candidate pVAX1-OmpB24. Lymphocytes and monocytes from 14 patients with Rickettsia were isolated from whole blood. Monocytes were differentiated into macrophages and transfected with the plasmid pVAX1-OmpB24 pVax1. Isolated lymphocytes were cultured with transfected macrophages. IFN-γ-producing TCD4+ and TCD8+ lymphocyte subpopulations were identified by flow cytometry, as was the percentage of macrophages expressing CD40+, CD80+, HLA-I and HLA-II. Also, we analyzed the exhausted condition of the T lymphocyte subpopulation by PD1 expression. Macrophages transfected with pVAX1-OmpB24 stimulated TCD4+INF-γ+ cells in healthy subjects and patients infected with R. typhi. Macrophages stimulated TCD8+INF-γ+ cells in healthy subjects and patients infected with R. rickettsii and R. felis. Cells from healthy donors stimulated with OmpB-24 showed a higher percentage of TCD4+PD1+. Cells from patients infected with R. rickettsii had a higher percentage of TCD8+PD-1+, and for those infected with R. typhi the larger number of cells corresponded to TCD4+PD1+. Human macrophages transfected with pVAX1-OmpB24 activated TCD4+IFN-γ+ and CD8+IFN-γ+ in patients infected with different Rickettsia species. However, PD1 expression played an important role in the inhibition of T lymphocytes with R. felis.

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Otomura, Flávio Haragushiku, Jessé Henrique Truppel, Jonas Moraes Filho, Marcelo Bahia Labruna, Diogo Francisco Rossoni, Rubens Massafera, Vanete Thomaz Soccol, and Ueslei Teodoro. "Probability of occurrence of the Brazilian spotted fever in northeast of Paraná state, Brazil." Revista Brasileira de Parasitologia Veterinária 25, no. 4 (December 1, 2016): 394–400. http://dx.doi.org/10.1590/s1984-29612016060.

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Abstract Brazilian spotted fever (BSF) is a fatal zoonosis because of the difficulties in its early diagnosis and treatment. Occurrences of BSF in the northeast of the state of Paraná prompted investigation of areas at risk of this rickettsiosis in the municipalities of Japira, Jaboti, Pinhalão and Tomazina. To determine the areas at risk, 592 serum samples from dogs and 230 from equids were analyzed by means of the indirect immunofluorescence assay (IFA) for Rickettsia rickettsii and R. parkeri . In addition, risk probability maps were drawn up using the kriging indicator technique. Among the samples tested, 5.3% (43/822) indicated presence of antibodies reactive to at least one of the two Rickettsia species tested: 7.8% of the equids (18/230) and 4.2% of the dogs (25/592) were positive. Geostatistical analysis showed that the average seropositivity rate was 5 to 6%. Although the average seropositivity rates observed among these dogs and equids were lower than those reported from endemic areas of Brazil, the biotic components (etiological agent, vector and reservoirs) and environmental aspects of BSF epidemiology were present in these municipalities.

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Segura Porta, Ferran. "Nuevas rickettsiosis." Medicina Clínica 122, no. 20 (January 2004): 784–85. http://dx.doi.org/10.1016/s0025-7753(04)74385-7.

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Kulkarni, Atul. "Childhood Rickettsiosis." Indian Journal of Pediatrics 78, no. 1 (October 22, 2010): 81–87. http://dx.doi.org/10.1007/s12098-010-0255-2.

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Ngamprasertchai, Thundon, Borimas Hanboonkunupakarn, and Watcharapong Piyaphanee. "Rickettsiosis in Southeast Asia: Summary for International Travellers during the COVID-19 Pandemic." Tropical Medicine and Infectious Disease 7, no. 2 (January 27, 2022): 18. http://dx.doi.org/10.3390/tropicalmed7020018.

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Rickettsiosis is an important cause of febrile illness among travellers visiting Southeast Asia (SEA). The true incidence of rickettsiosis is underestimated; however, murine typhus and scrub typhus are widely distributed across SEA. Among travellers visiting SEA, scrub typhus was mostly reported from Thailand, whereas murine typhus was frequently found in Indonesia. Although most cases are self-limited or present with mild symptoms, a few cases with severe clinical manifestations have been reported. Doxycycline remains the key treatment of rickettsiosis. Some travellers, such as backpackers, trekkers, or cave explorers, are at a higher risk for rickettsiosis than others. Therefore, in resource-limited conditions, empirical treatment should be considered in these travellers. The coronavirus disease 2019 (COVID-19) pandemic has contributed to difficulty in the diagnosis of rickettsiosis because of the clinical similarities between these diseases. In addition, physical distancing mandated by COVID-19 management guidelines limits accurate physical examination, resulting in misdiagnosis and delayed treatment of rickettsiosis. This review summarises the characteristics of murine typhus and scrub typhus, describes travel-associated rickettsiosis, and discusses the impact of the COVID-19 pandemic on rickettsiosis.

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Keller, Christian, Raphaël Rakotozandrindrainy, Vera von Kalckreuth, Jean Noël Heriniaina, Norbert Georg Schwarz, Gi Deok Pak, Justin Im, et al. "Molecular Evidence for Flea-Borne Rickettsiosis in Febrile Patients from Madagascar." Pathogens 10, no. 11 (November 14, 2021): 1482. http://dx.doi.org/10.3390/pathogens10111482.

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Rickettsiae may cause febrile infections in humans in tropical and subtropical regions. From Madagascar, no molecular data on the role of rickettsioses in febrile patients are available. Blood samples from patients presenting with fever in the area of the capital Antananarivo were screened for the presence of rickettsial DNA. EDTA (ethylenediaminetetraacetic acid) blood from 1020 patients presenting with pyrexia > 38.5 °C was analyzed by gltA-specific qPCR. Positive samples were confirmed by ompB-specific qPCR. From confirmed samples, the gltA amplicons were sequenced and subjected to phylogenetic analysis. From five gltA-reactive samples, two were confirmed by ompB-specific qPCR. The gltA sequence in the sample taken from a 38-year-old female showed 100% homology with R. typhi. The other sample taken from a 1.5-year-old infant was 100% homologous to R. felis. Tick-borne rickettsiae were not identified. The overall rate of febrile patients with molecular evidence for a rickettsial infection from the Madagascan study site was 0.2% (2/1020 patients). Flea-borne rickettsiosis is a rare but neglected cause of infection in Madagascar. Accurate diagnosis may prompt adequate antimicrobial treatment.

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LIM, M. Y., P. WEINSTEIN, A. BELL, T. HAMBLING, D. M. TOMPKINS, and D. SLANEY. "Seroprevalence of antibodies toRickettsia typhiin the Waikato region of New Zealand." Epidemiology and Infection 144, no. 11 (April 4, 2016): 2283–89. http://dx.doi.org/10.1017/s0950268816000698.

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SUMMARYThe first reported New Zealand-acquired case of murine typhus occurred near Auckland in 1989. Since then, 72 locally acquired cases have been recorded from northern New Zealand. By 2008, on the basis of the timing and distribution of cases, it appeared that murine typhus was escalating and spreading southwards. To explore the presence ofRickettsia typhiin the Waikato region, we conducted a seroprevalence study, using indirect immunofluorescence, Western blot, and cross-adsorption assays of blood donor samples. Of 950 human sera from Waikato, 12 (1·3%) hadR. typhiantibodies. The seroprevalence forR. typhiwas slightly higher in northern Waikato (1·4%) compared to the south (1·2%; no significant difference,χ2P= 0·768 atP< 0·05). Our results extend the reported southern range ofR. typhiby 140 km and indicate it is endemic in Waikato. Evidence of pastRickettsia felisinfections was also detected in six sera. Globally,R. felisis an emerging disease of concern and this pathogen should also be considered when locally acquired rickettsiosis is suspected. If public health interventions are to be implemented to reduce the risk of rickettsioses as a significant public health problem, improvements in rickettsial diagnostics and surveillance will be necessary.

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Berbis, P. "Rickettsioses." EMC - Dermatologie 2, no. 1 (January 2007): 1–10. http://dx.doi.org/10.1016/s0246-0319(07)45223-2.

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Lagier, J. C., B. Doudier, and P. Parola. "Rickettsioses." EMC - Traité de médecine AKOS 4, no. 2 (January 2009): 1–6. http://dx.doi.org/10.1016/s1634-6939(09)51283-5.

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Galvão, Márcio A. M., Joel A. Lamounier, Elido Bonomo, Margarete S. Tropia, Eliane G. Rezende, Simone B. Calic, Chequer B. Chamone, et al. "Rickettsioses emergentes e reemergentes numa região endêmica do Estado de Minas Gerais, Brasil." Cadernos de Saúde Pública 18, no. 6 (December 2002): 1593–97. http://dx.doi.org/10.1590/s0102-311x2002000600013.

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O trabalho descreve um inquérito sorológico para rickettsioses em escolares e cães de Novo Cruzeiro, Minas Gerais, Brasil, em 1998. Trezentos e trinta e um escolares pertenciam a uma área endêmica e 142 a uma área não endêmica do município. Trinta e nove (10,1%) soros foram reativos à Reação de Imunofluorescência Indireta (RIFI) para Rickettsia rickettsiino título de 1:64, sendo que dentre esses reativos, 35 eram de estudantes de escolas de área endêmica. Dentre os 73 cães analisados quanto à presença de anticorpos anti R. rickettsii, anti Ehrlichia chaffeensise anti Ehrlichia canisà RIFI no título de 1:64, 3 (4,11%), 11 (15,07%) e 13 (17,81%) desses animais foram reativos respectivamente aos antígenos testados. Conclui-se que, a sororeatividade para R. rickettsiiem indivíduos sadios sem história prévia de febre maculosa brasileira, uma doença marcante por sua alta letalidade, e a presença de sororeatividade para Ehrlichiacom potencial patogênico para o homem em cães, nos leva a indagar sobre a transmissão ao homem de outras espécies da família Rickettsiae na área estudada.

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Yuhana, Muhamad Yazli, Borimas Hanboonkunupakarn, Ampai Tanganuchitcharnchai, Pimpan Sujariyakul, Piengchan Sonthayanon, Kesinee Chotivanich, Sasithon Pukrittayakamee, Stuart D. Blacksell, and Daniel H. Paris. "Rickettsial Infections Are Neglected Causes of Acute Febrile Illness in Teluk Intan, Peninsular Malaysia." Tropical Medicine and Infectious Disease 7, no. 5 (May 18, 2022): 77. http://dx.doi.org/10.3390/tropicalmed7050077.

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Rickettsial infections are among the leading etiologies of acute febrile illness in Southeast Asia. However, recent data from Malaysia are limited. This prospective study was conducted in Teluk Intan, Peninsular Malaysia, during January to December 2016. We recruited 309 hospitalized adult patients with acute febrile illness. Clinical and biochemistry data were obtained, and patients were stratified into mild and severe infections based on the sepsis-related organ failure (qSOFA) scoring system. Diagnostic assays including blood cultures, real-time PCR, and serology (IFA and MAT) were performed. In this study, pathogens were identified in 214 (69%) patients, of which 199 (93%) patients had a single etiology, and 15 (5%) patients had >1 etiologies. The top three causes of febrile illness requiring hospitalization in this Malaysian study were leptospirosis (68 (32%)), dengue (58 (27%)), and rickettsioses (42 (19%)). Fifty-five (18%) patients presented with severe disease with a qSOFA score of >2. Mortality was documented in 38 (12%) patients, with the highest seen in leptospirosis (16 (42%)) followed by rickettsiosis (4 (11%)). While the significance of leptospirosis and dengue are recognized, the impact of rickettsial infections in Peninsular Malaysia remains under appreciated. Management guidelines for in-patient care with acute febrile illness in Peninsular Malaysia are needed.

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Chekanova, T. A., S. Zh Netalieva, S. N. Shpynov, M. A. Babaeva, and A. V. Kostarnoy. "RETROSPECTIVE SEROLOGICAL DIAGNOSTICS OF SPOTTED FEVER GROUP RIKKETSIOSES IN HIGH RISK AREAS OF RICKETTSIA CONORII SUBSP. CASPIA INFECTION." Russian Clinical Laboratory Diagnostics 64, no. 6 (October 7, 2019): 354–59. http://dx.doi.org/10.18821/0869-2084-2019-64-6-354-359.

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723 blood sera from 537 patients of Regional Infectious Clinical Hospital, Astrakhan were obtained during high activity period of Rhipicephalus ticks (May-September 2015) and retrospectively studied for IgG/IgM to antigen of spotted fever group (SFG) Rickettsia. IgG and/or IgM to Rickettsia conorii were detected in 145 sera from 130 patients, and antibodies to R. sibirica (group-specific) were detected in 143 sera from 145. Antibodies to R. conorii were detected for 71,4% patients with Astrakhan spotted fever (ASF), for 28,4% patients with acute respiratory viral infection, for 19,1% patients with infection of unspecified etiology and for 40% patients having symptoms of a adenovirus infection. Acute rickettsiosis, provably ASF, is serologically validated for 71 patients. Dynamic of IgM/IgG to R. conorii in sera of patients having different preliminary diagnoses is discussed. IgM to R. conorii in sera of patients having adenovirus infection symptoms were detected at a later time as compared with others. For regions of high risk of R. conorii subsp. caspia infection the differentiation of diagnostic and anamnestic specific antibodies is very important. The absence of serological and molecular biological markers in third of patients with ASF symptoms is necessary to study. Preparations and algorithms for diagnosis of SFG rickettsioses are needed to improve.

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BLANCO, J. R., and J. A. OTEO. "Rickettsiosis in Europe." Annals of the New York Academy of Sciences 1078, no. 1 (October 1, 2006): 26–33. http://dx.doi.org/10.1196/annals.1374.003.

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Botelho-Nevers, E. "Rickettsiosis y ehrlichiosis." EMC - Dermatología 48, no. 3 (September 2014): 1–10. http://dx.doi.org/10.1016/s1761-2896(14)68404-1.

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Mouallem, M., E. Friedman, R. Pauzner, E. Schwartz, and E. Rubinstein. "Rickettsiosis-associated hyponatremia." Infection 15, no. 5 (September 1987): 315–16. http://dx.doi.org/10.1007/bf01647728.

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Faccini-Martínez, Álvaro A., Sebastián Muñoz-Leal, Igor C. L. Acosta, Stefan Vilges de Oliveira, Ana Íris de Lima Duré, Crispim Cerutti, and Marcelo B. Labruna. "Confirming Rickettsia rickettsii as the etiological agent of lethal spotted fever group rickettsiosis in human patients from Espírito Santo state, Brazil." Ticks and Tick-borne Diseases 9, no. 3 (March 2018): 496–99. http://dx.doi.org/10.1016/j.ttbdis.2018.01.005.

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Yastrebov, V. K. "Modern nosoareas of tick-borne encephalitis and tick-borne rickettsiosis in Siberia." Bulletin of Siberian Medicine 5 (December 30, 2006): 131–36. http://dx.doi.org/10.20538/1682-0363-2006--131-136.

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Natural centers of tick-borne encephalitis and tick-borne rickettsiosis diseases are distinguished not only by stability and in- creasing level of epidemiological manifestation but also by ability to enlargement of areas. It is found that a contribution of some regions of Russia to the sick rate of tick-borne encephalitis and tick-borne rickettsiosis is changing in time. For tick-borne encephalitis the contribution of East Siberia increases and becomes equal to one of Ural area. For tick-borne rickettsiosis the general contribution of four regions (East Siberia, West Siberia, Ural and Far East) amount to 92% of diseases in country. The greater part of tick-borne rickettsiosis diseases (62,1%) is the contribution of East Siberia because of activi- ty of disease centers of Altai area.

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Phiri, Bruno S. J., Simone Kattner, Lidia Chitimia-Dobler, Silke Woelfel, Celina Albanus, Gerhard Dobler, and Thomas Küpper. "Rickettsia spp. in Ticks of South Luangwa Valley, Eastern Province, Zambia." Microorganisms 11, no. 1 (January 9, 2023): 167. http://dx.doi.org/10.3390/microorganisms11010167.

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Ticks are important vectors for Rickettsia spp. belonging to the Spotted Fever Group responsible for causing Rickettsiosis worldwide. Rickettsioses pose an underestimated health risk to tourists and local inhabitants. There is evidence of the presence of Rickettsia spp. in Zambia, however there is limited data. A total of 1465 ticks were collected in 20 different locations from dogs and cattle including one cat. Ticks were identified by morphological features or by sequencing of the 16S mitochondrial rRNA gene. Individual ticks were further tested for rickettsiae using a pan-Rickettsia real-time-PCR. Rickettsia species in PCR-positive ticks were identified by sequencing the 23S-5S intergenic spacer region or partial ompA gene, respectively. Seven tick species belonging to three different tick genera were found, namely: Amblyomma variegatum, Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) microplus, Rhipicephalus simus, Rhipicephalus sanguineus, Rhipicephalus zambesiensis and Haemaphysalis elliptica. Out of the 1465 ticks collected, 67 (4.6%) tested positive in the pan-Rickettsia PCR. This study provides detailed data about the presence of Rickettsia species in South Luangwa Valley, Eastern Province, Zambia for the first time. High prevalence of Rickettsia africae in Amblyomma variegatum was found, which indicates the potential risk of infection in the investigated area. Furthermore, to our best knowledge, this is the first time Rickettsia massiliae, a human pathogen causing spotted fever, has been detected in Zambia.

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OGRZEWALSKA, MARIA, DANILO G. SARAIVA, JONAS MORAES-FILHO, THIAGO F. MARTINS, FRANCISCO B. COSTA, ADRIANO PINTER, and MARCELO B. LABRUNA. "Epidemiology of Brazilian spotted fever in the Atlantic Forest, state of São Paulo, Brazil." Parasitology 139, no. 10 (May 1, 2012): 1283–300. http://dx.doi.org/10.1017/s0031182012000546.

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SUMMARYThe tick-borne bacteriumRickettsia rickettsiiis the aetiological agent of Brazilian spotted fever (BSF). The present study evaluated tick infestations on wild and domestic animals, and the rickettsial infection in these animals and their ticks in 7 forest areas adjacent to human communities in the São Paulo Metropolitan Area (SPMA). The results were compared to ecological traits of each sampled area. Two main tick species,Amblyomma aureolatumandRhipicephalus sanguineus,were collected from dogs. The major ticks found on small mammals and birds wereIxodes loricatusandAmblyomma longirostre, respectively. Both anti-R. rickettsiiantibodies andR. rickettsii-infected ticks were detected on dogs from only 2 areas in the southern part of the SPMA, which were considered to be endemic for BSF; the remaining 5 areas were considered to be non-endemic. Ecologically, the BSF-endemic areas clearly differed from the non-endemic areas by the presence of significantly more degraded forest patches in the former. The present results corroborate historical observations that have indicated that all human cases of BSF in the SPMA were contracted in the southern part of this metropolitan area. However, not all forest patches in the southern part of the SPMA were shown to be associated with BSF endemism.

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Schjørring, Susanne, Martin Tugwell Jepsen, Camilla Adler Sørensen, Palle Valentiner-Branth, Bjørn Kantsø, Randi Føns Petersen, Ole Skovgaard, and Karen A. Krogfelt. "Laboratory Diagnostics of Rickettsia Infections in Denmark 2008–2015." Biology 9, no. 6 (June 19, 2020): 133. http://dx.doi.org/10.3390/biology9060133.

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Rickettsiosis is a vector-borne disease caused by bacterial species in the genus Rickettsia. Ticks in Scandinavia are reported to be infected with Rickettsia, yet only a few Scandinavian human cases are described, and rickettsiosis is poorly understood. The aim of this study was to determine the prevalence of rickettsiosis in Denmark based on laboratory findings. We found that in the Danish individuals who tested positive for Rickettsia by serology, the majority (86%; 484/561) of the infections belonged to the spotted fever group. In contrast, we could confirm 13 of 41 (32%) PCR-positive individuals by sequencing and identified all of these as R. africae, indicating infections after travel exposure. These 13 samples were collected from wound/skin material. In Denmark, approximately 85 individuals test positive for Rickettsia spp. annually, giving an estimated 26% (561/2147) annual prevalence among those suspected of rickettsiosis after tick bites. However, without clinical data and a history of travel exposure, a true estimation of rickettsiosis acquired endemically by tick bites cannot be made. Therefore, we recommend that both clinical data and specific travel exposure be included in a surveillance system of Rickettsia infections.

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Raoult, D. "S154 Rickettsioses." International Journal of Antimicrobial Agents 29 (March 2007): S31. http://dx.doi.org/10.1016/s0924-8579(07)70100-0.

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Hansmann, Y. "Rickettsioses éruptives." EMC - Maladies infectieuses 6, no. 2 (January 2009): 1–15. http://dx.doi.org/10.1016/s1166-8598(09)44183-8.

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Parola, Philippe, and Didier Raoult. "Tropical rickettsioses." Clinics in Dermatology 24, no. 3 (May 2006): 191–200. http://dx.doi.org/10.1016/j.clindermatol.2005.11.007.

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Blanton, Lucas S. "The Rickettsioses." Infectious Disease Clinics of North America 33, no. 1 (March 2019): 213–29. http://dx.doi.org/10.1016/j.idc.2018.10.010.

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Romer, Yamila. "Rickettsia parkeri Rickettsiosis, Argentina." Emerging Infectious Diseases 17, no. 7 (July 2011): 1169–73. http://dx.doi.org/10.3201/eid1707.101857.

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Ellison, Damon W., Tina R. Clark, Daniel E. Sturdevant, Kimmo Virtaneva, Stephen F. Porcella, and Ted Hackstadt. "Genomic Comparison of Virulent Rickettsia rickettsii Sheila Smith and Avirulent Rickettsia rickettsii Iowa." Infection and Immunity 76, no. 2 (November 19, 2007): 542–50. http://dx.doi.org/10.1128/iai.00952-07.

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ABSTRACT Rickettsia rickettsii is an obligate intracellular pathogen that is the causative agent of Rocky Mountain spotted fever. To identify genes involved in the virulence of R. rickettsii, the genome of an avirulent strain, R. rickettsii Iowa, was sequenced and compared to the genome of the virulent strain R. rickettsii Sheila Smith. R. rickettsii Iowa is avirulent in a guinea pig model of infection and displays altered plaque morphology with decreased lysis of infected host cells. Comparison of the two genomes revealed that R. rickettsii Iowa and R. rickettsii Sheila Smith share a high degree of sequence identity. A whole-genome alignment comparing R. rickettsii Iowa to R. rickettsii Sheila Smith revealed a total of 143 deletions for the two strains. A subsequent single-nucleotide polymorphism (SNP) analysis comparing Iowa to Sheila Smith revealed 492 SNPs for the two genomes. One of the deletions in R. rickettsii Iowa truncates rompA, encoding a major surface antigen (rickettsial outer membrane protein A [rOmpA]) and member of the autotransporter family, 660 bp from the start of translation. Immunoblotting and immunofluorescence confirmed the absence of rOmpA from R. rickettsii Iowa. In addition, R. rickettsii Iowa is defective in the processing of rOmpB, an autotransporter and also a major surface antigen of spotted fever group rickettsiae. Disruption of rompA and the defect in rOmpB processing are most likely factors that contribute to the avirulence of R. rickettsii Iowa. Genomic differences between the two strains do not significantly alter gene expression as analysis of microarrays revealed only four differences in gene expression between R. rickettsii Iowa and R. rickettsii strain R. Although R. rickettsii Iowa does not cause apparent disease, infection of guinea pigs with this strain confers protection against subsequent challenge with the virulent strain R. rickettsii Sheila Smith.

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Zaitseva, O. A., O. A. Gnusareva, O. V. Vasil’eva, A. S. Volynkina, Yu V. Siritsa, Yu A. Alekhina, T. I. Chishenyuk, et al. "Results of Epizootiological Monitoring of Natural Foci for Bacterial Vector-Borne Infections in Caucasian Mineral Waters Region of the Stavropol Territory in 2018–2020." Problems of Particularly Dangerous Infections, no. 1 (April 19, 2022): 101–5. http://dx.doi.org/10.21055/0370-1069-2022-1-101-105.

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The aim of the study was to assess the epizootiological situation on bacterial vector-borne infections in Caucasian Mineral Waters area of the Stavropol Territory over the period of 2018–2020.Materials and methods. 3494 specimens of ticks (473 pools), 257 specimens of small mammals, 9 regurgitates of birds of prey and mammals, 7 excreta samples of small mammals, and 2 water samples were tested. Laboratory research of the field material was carried out using molecular-genetic, serological, biological methods. Statistical analysis of laboratory results was conducted using Microsoft Excel 2010. The data were mapped using QGIS 2.18 software.Results and discussion. The study revealed that the 44.8 % of collected ticks were positive for tick-borne borreliosis, 21.5 % – for tick-borne rickettsiosis, 10.3% – for human granulocytic anaplasmosis, 2.7 % – for Q fever, 0.84 % – for tularemia. There has been an increase in the percentage of positives for tick-borne borreliosis agent samples (more than three times) and a decrease in this indicator for human granulocytic anaplasmosis (1.5 times) as compared with 2010–2012. Investigation of tick infection with the agents of Q fever and tick-borne rickettsioses has not been previously conducted in the region. During the period under review, 19 pools of ticks had mixed infection, which indicates that there are combined foci of bacterial natural-focal infections with vector-borne transmission in the recreation zone of the Stavropol Territory. This necessitates preventive measures and systematical epizootiological surveys in the Caucasian Mineral Waters region.

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Colonia, Carol B., Alejandro Ramírez-Hernández, Juliana Gil-Mora, Juan C. Agudelo, Gabriel Jaime Castaño Villa, Camilo Pino, Paola Betancourt-Ruiz, Jorge E. Pérez Cárdenas, Lucas S. Blanton, and Marylin Hidalgo. "Flea-borne Rickettsia species in fleas, Caldas department, Colombia." Journal of Infection in Developing Countries 14, no. 10 (October 31, 2020): 1155–63. http://dx.doi.org/10.3855/jidc.12524.

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Introduction: Rickettsioses are zoonotic diseases caused by pathogenic bacteria of the genus Rickettsia and transmitted to man by means of arthropod vectors such as ticks, fleas, mites and lice. Historically, Caldas Department has reported a significant number of cases of murine typhus to the Colombian national health surveillance system, and consequent studies of flea-borne rickettsiosis identified the circulation of Rickettsia typhi and Rickettsia felis in multiple municipalities. Our aim was to genotype species of Rickettsia detected in fleas collected from domestic and wild mammals in Caldas. Methodology: Flea samples were taken by convenience sampling from dogs, cats and wild mammals (rodents and marsupials) in 26 municipalities. Specimens were classified by current taxonomic keys and pooled for DNA extraction and molecular screening for Rickettsia spp. by PCR amplification of gltA, htrA and sca5 genes. Positive samples were genotyped by enzyme digestion (htrA) and sequencing. Results: A total of 1388 flea samples were collected. Rickettsia DNA was amplified in 818 (gltA), 883 (htrA) and 424 (sca5) flea pools. Alignment analysis with available Rickettsia DNA sequences showed greater similarity with R. asembonensis (gltA) and with R. felis (sca5 and htrA). Restriction pattern was compatible with R. felis. R. typhi was not identified. Conclusion: The present study confirms the presence and high prevalence of R. asembonensis and R. felis in fleas from domestic and wild animals in different municipalities from Caldas Department.

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Злобин, Vladimir Zlobin, Петрова, Alla Petrova, Сидорова, Kseniya Sidorova, Джиоев, and Yuriy Dzhioev. "tick-borne rickettsiosis in children of the irkutsk region over five epidemic seasons." Бюллетень Восточно-Сибирского научного центра Сибирского отделения Российской академии медицинских наук 1, no. 5 (December 6, 2016): 49–53. http://dx.doi.org/10.12737/23350.

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The article discusses the clinical and laboratory characteristics of tick-borne rickettsiosis in children in the Irkutsk region on the results of the retrospective study of 65 patients admitted to the Regional Infectious Hospital over the period of five consecutive epidemic seasons. It has been found that among hospitalized children with tick-borne rick-ettsiosis dominating proportion (64.6 %) is of rural residents (mean age – 5 years old). The main clinical symptoms in children borne rickettsiosis were rash (96.9 %) and fever (96.9 %), which in one third of observations associated with lymphadenopathy (38.5%). About one third of patients (30.8 %) had pronounced symptoms of intoxication. It has been noted that the laboratory diagnosis of tick-borne rickettsiosis needs to be improved: DGC reaction should replace ELISA detection of specific immunoglobulin M in the blood in combination with PCR for genetic identification of rickettsiae. The development of emergency preventive treatment of tick-borne rickettsiosis is required, taking into account the sensitivity of rickettsiae to antibiotics. All children with tick-borne rickettsial diseases were provided with timely and effective treatment, with favorable prognosis.

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Peña Ríosa, Yiyola, Oscar Eduardo López, and Yadira Borrero Ramírez. "Caracterización de los determinantes sociales de las Rickettsiosis en El Jigual, Rosas, Cauca en el año 2016. Un estudio de caso cualitativo." Gerencia y Políticas de Salud 18, no. 37 (November 7, 2019): 1–32. http://dx.doi.org/10.11144/javeriana.rgps18-37.cdsr.

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Introducción: las Rickettsiosis representan un desafío para la salud pública por su letalidad, complejidad diagnóstica, desconocimiento del personal de salud, las comunidades y difícil control; aunque Colombia ha tenido brotes, no hay estudios sobre los determinantes sociales de las Rickettsiosis. Objetivo: caracterizar los determinantes sociales de las Rickettsiosis en la vereda Jigual (Colombia). Métodos: estudio de caso cualitativo, instrumental, con diseño etnográfico. Resultados: se encontró una población en condiciones de pobreza, con alto índice de necesidades básicas insatisfechas, alta dependencia económica, baja escolaridad, producción agropecuaria artesanal, con ampliación de la frontera agrícola por presión sobre los suelos y percepción de incremento de la temperatura local, con aumento de infestación por garrapatas. No se encontró percepción de riesgo frente al vector en la comunidad; además, la respuesta institucional ha sido desarticulada y discontinua. Discusión: las Rickettsiosis son un reto para la salud pública, debido a la complejidad de las condiciones sociales asociadas y la ausencia de percepción de riesgo; algunos autores coinciden en que los brotes epidémicos están relacionados con rezago social y la percepción de riesgo de exposición al vector.

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Ando, S., and Y. Ogasawara. "Traveler's rickettsioses and domestic rickettsioses in Japan in 2011." International Journal of Infectious Diseases 16 (June 2012): e337. http://dx.doi.org/10.1016/j.ijid.2012.05.398.

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Journal articles on the topic 'Rickettsiosi'

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