Academic literature on the topic 'Theileria parva – South Africa'
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Journal articles on the topic "Theileria parva – South Africa"
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PIENAAR, RONEL, ABDALLA A. LATIF, ORIEL M. M. THEKISOE, and BEN J. MANS. "Geographic distribution of Theileria sp. (buffalo) and Theileria sp. (bougasvlei) in Cape buffalo (Syncerus caffer) in southern Africa: implications for speciation." Parasitology 141, no. 3 (November 7, 2013): 411–24. http://dx.doi.org/10.1017/s0031182013001728.
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SUMMARYStrict control measures apply to movement of buffalo in South Africa including testing for Theileria parva, the causative agent of Corridor disease in cattle. The official test is a real-time hybridization PCR assay that amplifies the 18S rRNA V4 hyper-variable region of T. parva, T. sp. (buffalo) and T. sp. (bougasvlei). Mixed infections with the latter organisms affect diagnostic sensitivity due to PCR suppression. While the incidence of mixed infections in the Corridor disease endemic region of South Africa is significant, little information is available on the specific distribution and prevalence of T. sp. (buffalo) and T. sp. (bougasvlei). Specific real-time PCR assays were developed and a total of 1211 samples known to harbour these parasites were screened. Both parasites are widely distributed in southern Africa and the incidence of mixed infections with T. parva within the endemic region is similar (∼25–50%). However, a significant discrepancy exists in regard to mixed infections of T. sp. (buffalo) and T. sp. (bougasvlei) (∼10%). Evidence for speciation between T. sp. (buffalo) and T. sp. (bougasvlei) is supported by phylogenetic analysis of the COI gene, and their designation as different species. This suggests mutual exclusion of parasites and the possibility of hybrid sterility in cases of mixed infections.
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Norval, R. A. I., J. A. Lawrence, A. S. Young, B. D. Perry, T. T. Dolan, and J. Scott. "Theileria parva: influence of vector, parasite and host relationships on the epidemiology of theileriosis in southern Africa." Parasitology 102, no. 3 (June 1991): 347–56. http://dx.doi.org/10.1017/s0031182000064295.
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The protozoan parasite Theileria parva, transmitted by the ixodid tick Rhipicephalus appendiculatus, is the cause of East Coast fever (ECF) and the related syndromes of Corridor disease and January disease in cattle of eastern, central and southern Africa. It is likely that buffalo (Syncerus caffer) are the natural host of T. parva. In eastern and southern Africa, there exist both buffalo-adapted and cattle-adapted T. parva. Disease caused by buffalo-adapted parasites is called Corridor disease, and that caused by cattle-adapted parasites is termed East Coast fever. In eastern Africa, it has been shown experimentally that buffalo-adapted T. parva can, after serial passage in cattle, become adapted to cattle, in which it can then be maintained and cause ECF. This adaptation has been termed transformation. The transformation of buffalo-adapted T. parva to a cattle-adapted parasite has not been reported in southern Africa, and ECF, eradicated from South Africa, Swaziland and southern Mozambique by 1960, has not reappeared in the subcontinent. This paper discusses the possible reasons for this, and hypothesizes that vector population dynamics and the susceptibility of the vector population to infection with T. parva are among the most important factors which influence the expression of ECF as a disease entity, and the likelihood of transformation occurring. It also considers the possibility that disappearance of ECF from southern Africa resulted from the extinction, as a result of vigorous control measures and unfavourable climatic conditions, of non-diapausing populations of R. appendiculatus that may have been introduced from eastern Africa with cattle imported in 1901.
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Sibeko, Kgomotso P., Dirk Geysen, Marinda C. Oosthuizen, Conrad A. Matthee, Milana Troskie, Frederick T. Potgieter, Jacobus A. W. Coetzer, and Nicola E. Collins. "Four p67 alleles identified in South African Theileria parva field samples." Veterinary Parasitology 167, no. 2-4 (February 2010): 244–54. http://dx.doi.org/10.1016/j.vetpar.2009.09.026.
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Mbizeni, Sikhumbuzo, Fred T. Potgieter, Christo Troskie, Ben J. Mans, Barend L. Penzhorn, and Abdalla A. Latif. "Field and laboratory studies on Corridor disease (Theileria parva infection) in cattle population at the livestock/game interface of uPhongolo-Mkuze area, South Africa." Ticks and Tick-borne Diseases 4, no. 3 (April 2013): 227–34. http://dx.doi.org/10.1016/j.ttbdis.2012.11.005.
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Sibeko, Kgomotso P., Nicola E. Collins, Marinda C. Oosthuizen, Milana Troskie, Frederick T. Potgieter, Jacobus A. W. Coetzer, and Dirk Geysen. "Analyses of genes encoding Theileria parva p104 and polymorphic immunodominant molecule (PIM) reveal evidence of the presence of cattle-type alleles in the South African T. parva population." Veterinary Parasitology 181, no. 2-4 (September 2011): 120–30. http://dx.doi.org/10.1016/j.vetpar.2011.04.035.
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Medley, G. F., B. D. Perry, and A. S. Young. "Preliminary analysis of the transmission dynamics of Theileria parva in eastern Africa." Parasitology 106, no. 3 (April 1993): 251–64. http://dx.doi.org/10.1017/s0031182000075077.
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SUMMARYTwo mathematical models are developed that investigate the transmission dynamics of Theileria parva by the ixodid tickRhipicephalus appendiculatus to cattle in endemically stable areas. A method of estimating the rate of infection to cattle ofT. parva at the endemically stable state is given. Empirical estimates of ail the parameters in the model are available. The degree to which animals that have recovered from theileriosis (the ‘carrier’ state) are able to transmit the infection to tick nymphs or larvae is a crucial determinant of the dynamics of infection in a herd. Two control methods influencing the transmission of infection are considered – infection and treatment immunization and the reduction in tick feeding by acaricide application. The impact of each method on the transmission of infection is evaluated. Future developments and the data required to predict the dynamics of T. parva infections in cattle and ticks are discussed.
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Salih, Diaeldin A., Joram M. Mwacharo, Roger Pelle, Moses N. Njahira, David O. Odongo, Mary N. Mbole-Kariuki, Wani L. Marcellino, et al. "Genetic diversity and population structure of Theileria parva in South Sudan." Ticks and Tick-borne Diseases 9, no. 4 (May 2018): 806–13. http://dx.doi.org/10.1016/j.ttbdis.2018.03.002.
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KIARA, H., A. JENNINGS, B. M. DE C. BRONSVOORT, I. G. HANDEL, S. T. MWANGI, M. MBOLE-KARIUKI, I. CONRADIE VAN WYK, et al. "A longitudinal assessment of the serological response toTheileria parvaand other tick-borne parasites from birth to one year in a cohort of indigenous calves in western Kenya." Parasitology 141, no. 10 (May 16, 2014): 1289–98. http://dx.doi.org/10.1017/s003118201400050x.
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SUMMARYTick-borne diseases are a major impediment to improved productivity of livestock in sub-Saharan Africa. Improved control of these diseases would be assisted by detailed epidemiological data. Here we used longitudinal, serological data to determine the patterns of exposure toTheileria parva, Theileria mutans, Babesia bigeminaandAnaplasma marginalefrom 548 indigenous calves in western Kenya. The percentage of calves seropositive for the first three parasites declined from initial high levels due to maternal antibody until week 16, after which the percentage increased until the end of the study. In contrast, the percentage of calves seropositive forT. mutansincreased from week 6 and reached a maximal level at week 16. Overall 423 (77%) calves seroconverted toT. parva, 451 (82%) toT. mutans, 195 (36%) toB. bigeminaand 275 (50%) toA. marginale. Theileria parvaantibody levels were sustained following infection, in contrast to those of the other three haemoparasites. Three times as many calves seroconverted toT. mutansbefore seroconverting toT. parva. NoT. parvaantibody response was detected in 25 calves that died ofT. parvainfection, suggesting that most deaths due toT. parvaare the result of acute disease from primary exposure.
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Mwamuye, Micky M., Isaiah Obara, Khawla Elati, David Odongo, Mohammed A. Bakheit, Frans Jongejan, and Ard M. Nijhof. "Unique Mitochondrial Single Nucleotide Polymorphisms Demonstrate Resolution Potential to Discriminate Theileria parva Vaccine and Buffalo-Derived Strains." Life 10, no. 12 (December 8, 2020): 334. http://dx.doi.org/10.3390/life10120334.
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Distinct pathogenic and epidemiological features underlie different Theileria parva strains resulting in different clinical manifestations of East Coast Fever and Corridor Disease in susceptible cattle. Unclear delineation of these strains limits the control of these diseases in endemic areas. Hence, an accurate characterization of strains can improve the treatment and prevention approaches as well as investigate their origin. Here, we describe a set of single nucleotide polymorphisms (SNPs) based on 13 near-complete mitogenomes of T. parva strains originating from East and Southern Africa, including the live vaccine stock strains. We identified 11 SNPs that are non-preferentially distributed within the coding and non-coding regions, all of which are synonymous except for two within the cytochrome b gene of buffalo-derived strains. Our analysis ascertains haplotype-specific mutations that segregate the different vaccine and the buffalo-derived strains except T. parva-Muguga and Serengeti-transformed strains suggesting a shared lineage between the latter two vaccine strains. Phylogenetic analyses including the mitogenomes of other Theileria species: T. annulata, T. taurotragi, and T. lestoquardi, with the latter two sequenced in this study for the first time, were congruent with nuclear-encoded genes. Importantly, we describe seven T. parva haplotypes characterized by synonymous SNPs and parsimony-informative characters with the other three transforming species mitogenomes. We anticipate that tracking T. parva mitochondrial haplotypes from this study will provide insight into the parasite’s epidemiological dynamics and underpin current control efforts.
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Chaisi, Mamohale E., Kgomotso P. Sibeko, Nicola E. Collins, Fred T. Potgieter, and Marinda C. Oosthuizen. "Identification of Theileria parva and Theileria sp. (buffalo) 18S rRNA gene sequence variants in the African Buffalo (Syncerus caffer) in southern Africa." Veterinary Parasitology 182, no. 2-4 (December 2011): 150–62. http://dx.doi.org/10.1016/j.vetpar.2011.05.041.
Full textDissertations / Theses on the topic "Theileria parva – South Africa"
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Sibeko, K. P. (Kgomotso Penelope). "Improved molecular diagnostics and characterization of Theileria parva isolates from cattle and buffalo in South Africa." Thesis, University of Pretoria, 2010. http://hdl.handle.net/2263/24872.
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The aim of this study was to improve the official diagnostic test package in South Africa for detection of Theileria parva infections in cattle and Cape buffalo (Syncerus caffer) and to investigate the presence of cattle-type T. parva parasites in buffalo and cattle in South Africa. To improve diagnosis of T. parva infections, a T. parva-specific real-time polymerase chain reaction (PCR) assay based on hybridization probe technology was developed. Oligonucleotide primers and hybridization probes used in the assay were designed based on the 18S ribosomal RNA (rRNA) gene. The primers amplify T. parva and Theileria sp. (buffalo) DNA but the hybridization probes specifically detect T. parva amplicons. Because of the high sequence similarity between the T. parva and Theileria sp. (buffalo) 18S rRNA genes, amplification of Theileria sp. (buffalo) DNA could not be avoided; no other bovine blood pathogens tested were amplified by these primers. The real-time PCR assay demonstrated superior sensitivity compared to other molecular tests used in detection of T. parva infections, reliably detecting the parasite in carrier animals with a piroplasm parasitaemia as low as 8.79x10-4% with minute template DNA input. The assay requires less time to perform with a low risk of contamination because of the closed-tube system that does not require handling of amplicons for post-PCR analysis. The presence of cattle-typeT. parva parasites in buffalo and cattle was investigated using restriction fragment length polymorphism (RFLP) profiles of PCR products and sequences of the parasite genes which code for the antigenic proteins p67, p104, and the polymorphic immunodominant molecule (PIM). Cattle-type p67, p104 and PIM alleles were identified from three T. parva samples obtained from cattle from a farm near Ladysmith in the KwaZulu-Natal Province. These cattle-type alleles were identical to those previously identified from a cattle-derived T. parva stock, T. parva Muguga, a parasite stock that causes East Coast fever (ECF) in Kenya; however, ECF was not diagnosed in animals in this farm. Cattle-type alleles identical to those previously reported were not identified from T. parva buffalo samples, but variants of p67 allele 1 as well as p104 allele 1, both previously obtained from T. parva Muguga, were identified. It is not known if parasites that possess these variants can cause disease, and the risk of their adapting to cattle as in the case of ECF and January disease needs to be evaluated. Furthermore, these findings suggest that cattle-like alleles may not be exclusively associated with cattle-derived T. parva parasites. Most of the p67, p104 and PIM gene sequences obtained in this study were not identical to known sequences; furthermore, novel alleles were identified, demonstrating extensive genetic diversity in the South African T. parva parasite population in buffalo. The significance of the parasites that possess ‘novel’ alleles in the epidemiology of theileriosis in South Africa still needs to be determined. The identification of variants and novel alleles reveals that p67, p104 and PIM gene PCR-RFLP profiles are more complex than previously thought and the classification of buffalo- and cattle-derived T. parva parasites in South Africa based on p67, p104 and PIM gene profiles would not be possible. Identification of more reliable markers that can be directly associated with the theilerial disease syndromes remains a challenge.Thesis (PhD)--University of Pretoria, 2009.
Veterinary Tropical Diseases
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Thompson, Bronwen Eleanor. "Occurrence of Theileria parva infection in cattle on a farm in KwaZulu-Natal, South Africa." Diss., Electronic thesis, 2007. http://upetd.up.ac.za/thesis/available/etd-11012007-133653/.
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Tosas, Auguet Olga. "Interactions amongst the community of endemic pathogens of African cattle : a longitudinal study in south east Uganda." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/1517.
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The work presented in this thesis is focused upon the community of endemic pathogens of African cattle in Sub-Saharan Africa, which has long constrained livestock production in these areas. The first aim of this work is to investigate whether the pathogen community as a whole shapes the ensuant epidemiology and morbidity which are currently attributed to any of its individual pathogens. The second aim is to determine if a greater understanding of the interactions present amongst genetically distinct parasites of the same species can be used to better explain epidemiological features that are at present poorly understood. Emphasis is placed on examining spatial variation in the epidemiology of Theileria parva, a tick-transmitted protozoan that causes East Coast Fever. To achieve these aims, this work examines field data collected from a large and comprehensive study conducted in south east Uganda. Through application of apposite statistical techniques and mathematical modelling, aspects of the complex relations amongst the pathogen community and their environment are explored. Evidence is presented that demonstrates the paramount role of the pathogen community as a whole in shaping the infection dynamics and pathogenicity of any of its individual components. By focusing on a single member of this pathogen community (Theileria parva), some of the influences of host, vector, geographical location, temporal dynamics and intra-species pathogen interactions are elucidated. Application of a polymorphic molecular marker to Theileria parva infected blood samples and the use of Cox proportional hazard analysis, show variability in the survival of infections in cattle in high and low tick challenge areas. Moreover infection survival, which plays a pivotal role in parasite transmission, is shown to be a function of the interactions established amongst genetically distinct co-infective parasites. In consequence, vector intensity alone is insufficient to develop reliable transmission models which can accurately predict the epidemiology of the parasite inside and outside enzootic belts. Finally, a theoretical model is developed which, based upon the field evidence obtained throughout this work, provides a possible explanation for the mechanics of T. parva survival in cattle. In summary, this thesis makes a case that consideration of both inter- and intra-species pathogen interactions, can greatly augment understanding of the epidemiology of these pathogen communities. An integrated approach to pathogen dynamics can better equip an integrated approach to control of important diseases of African cattle.
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Choopa, Chimvwele Namantala. "Diagnosis of tick-borne diseases in cattle in Bushbuckridge Mpumalanga South Africa and identification of Theileria parva carriers." Diss., University of Pretoria, 2015. http://hdl.handle.net/2263/53321.
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The Mnisi community is in the north-eastern corner of the Bushbuckridge Municipal Area, Mpumalanga Province, South Africa. This community is located at the livestock/wildlife interface sharing borders with several game reserves, and livestock are likely to be exposed to diseases with a wildlife reservoir, such as Corridor disease. Known tick vectors of important diseases such as Corridor disease, redwater, heartwater and anaplasmosis are present in the area. Although the farmers frequently dip their cattle in acaricide-filled dip tanks to control the tick burden, tick-borne diseases (TBDs) are still a major problem. This study was undertaken to determine if the symptoms of cattle in poor health in the Mnisi community could be attributed to TBDs. Corridor disease has previously been identified in cattle in the Mnisi community. Recent experimental studies have shown that T. parva DNA can be detected in infected cattle that survive the disease in the field. An additional aim of the study was therefore to identify T. parva carrier cattle in the area, and to search for evidence of selection of cattle-adapted T. parva parasites in carrier cattle.
The study was conducted from July 2012 to June 2013. During the study period, samples from clinically sick cattle suspected of TBDs were collected to determine the cause of their symptoms. Blood smears from the clinically sick cattle were analysed using light microscopy while some cases were subjected to histopathology and T. parva-specific quantitative real-time polymerase chain reaction (qPCR). DNA extracted from blood samples and in some cases tissue samples collected from clinically sick cattle (n=137) was tested for the presence of haemoparasite DNA using the reverse line blot (RLB) hybridization assay. To identify T. parva carrier cattle, records from Hluvukani Animal Clinic and Bushbuckridge State Veterinary office were scrutinized to identify herds that may have been exposed to T. parva infection. Blood samples (n=670) were collected from herds that had recorded Corridor disease cases in the past three years, as well as herds that may have shared grazing with buffalo from the Kruger National Park and surrounding private game reserves. The indirect fluorescent antibody test (IFAT) was used to check for T. parva antibodies. Seropositive herds were revisited, as well as herds that had confirmed Corridor disease cases during the study period, and blood samples were collected (n=432). DNA extracted from these samples was screened for the presence of T. parva DNA using the T. parva-specific qPCR. In an attempt to find evidence of selection of cattle-adapted T. parva, the p67, p104 and PIM parasite genes were amplified from qPCR positive samples, and the amplicons were cloned and sequenced.
Out of the 137 clinical disease cases examined from the study area, 24 cases of TBDs were diagnosed, of which 19 were Theileria related. The RLB hybridization assay confirmed the presence of tick-borne haemoparasites in the Mnisi community: 89 of the 137 clinical disease cases (65.0%) were found positive for one or more haemoparasite (Theileria, Babesia, Anaplasma and/or Ehrlichia species) while 48 (35.0%) were negative or below the detectable limit of the test.
IFAT results indicated that there is a high seroprevalence of theileriosis (63.6%) in the Mnisi community area, but this may be due to cross reactions with other Theileria parasites known to be present (e.g. T. taurotragi). Fewer cattle (13.4%) were seropositive at the highest titre tested (160), and these are most likely to be associated with T. parva. In DNA extracted from blood samples from these seropositive herds, the T. parva-specific qPCR detected T. parva in eleven samples (2.6%). Eight of the eleven cattle were re-sampled six months later, but only one was still qPCR positive. All of the p104 and PIM sequences and two of the three p67 sequences were characteristic of buffalo-type T. parva alleles previously identified, implying that the T. parva infections in the cattle were transmitted directly from buffalo to cattle, and providing no evidence of selection of cattle-type alleles in the carrier animals.
The study revealed that TBDs are a problem in the Mnisi community and surrounding area. Most important of the TBDs identified was Corridor disease, a notifiable disease in South Africa, which was the cause of most deaths among the cattle that were sampled. There was no evidence for the selection of cattle-derived T. parva alleles in any of the samples from T. parva carrier cattle, but a p67 sequence obtained from a clinical case was closely related to previously-identified alleles from cattle-derived isolates. Theileria parva DNA could only be detected in carrier cattle for a limited time post-exposure, suggesting that the infection will be cleared in infected animals before larvae or nymphs are available to pick up infections the following season. However, one bovine was still qPCR positive six months post-exposure, albeit with a very high Cp value (indicating a very low parasitaemia). The selection of T. parva parasites in cattle from the diverse T. parva population in African buffalo, therefore, remains a concern in the Mnisi community area, and at other livestock/wildlife interfaces in South Africa, but the risk is probably very low.Dissertation (MSc)--University of Pretoria, 2015.
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Veterinary Tropical Diseases
MSc
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Stoltsz, Wilhelm Heinrich. "Aspects of the epidemiology of Theileria parva infections in cattle and African buffalo (Syncerus caffer) in South Africa revealed by tick transmission and sub-inoculation of blood." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/24952.
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The aim of this study was to investigate three key epidemiological aspects of Theileria parva infections in cattle and African buffalo (Syncerus caffer) in South Africa. The first of these was the possible behavioural change (i.e. transformation) of buffalo-derived T. parva (causing classical Corridor disease in cattle) to what might be considered cattle-derived T. parva (causing classical East Coast fever in cattle) after repeated tick-passage in cattle. For the first time a South African isolate of buffalo-derived T. parva was successfully transmitted using Rhipicephalus zambeziensis for eight passages in non-splenectomised cattle. This was achieved despite most animals developing fatal infections with extremely low piroplasm parasitaemias, and without chemotherapeutic intervention. This finding indicates that, contrary to earlier belief, Corridor disease is not a self-limiting disease in cattle, and given the opportunity, could well become established in a cattle population in the absence of buffalo. Despite repeated tick transmission in cattle of the South African buffalo isolate of T. parva used in this study, it did not exhibit the behavioural changes associated with “transformation” to typical cattle-derived T. parva. Secondly, the potential role of the common waterbuck (Kobus ellipsiprymnus) in the selection of cattle-adapted subpopulations of parasites from buffalo-derived T. parva was investigated. Waterbuck captured in Kruger National Park (KNP) were screened by conventional and molecular diagnostic techniques for Theileria spp. infections. Laboratory-reared R. zambeziensis were fed on captive buffalo confirmed to be naturally infected with T. parva. The ensuing adult ticks were fed on captive waterbuck and cattle. All the waterbuck were found to carry microscopically detectable Theileria sp. piroplasm infections, found by polymerase chain reaction (PCR) diagnosis to belong to a hitherto uncharacterised Theileria species. R. zambeziensis adults which fed as nymphs on the buffalo transmitted fatal T. parva infections to cattle. However, no transmission of T. parva to the waterbuck could be demonstrated clinically or by PCR diagnosis. Also, R. zambeziensis nymphs that were subsequently fed on the waterbuck failed to transmit T. parva to cattle in the ensuing adult stage, confirming the absence of T. parva-group infections in the waterbuck. The results suggest that buffalo in KNP probably do not carry T. parva-group parasites which are readily transmissible to common waterbuck and waterbuck are therefore unlikely to play an important role in the epidemiology of T. parva-group infections in cattle in South Africa. Thirdly, to investigate the carrier state of buffalo-derived T. parva infections in cattle, blood from infected non-splenectomised and splenectomised carrier cattle was subinoculated to splenectomised cattle. T. parva infections were successfully transmitted by subinoculation of 1000 ml of blood at various intervals after infection to splenectomised recipient cattle. Donor animals comprised of recovered intact cattle, reacting intact cattle or splenectomised recovered cattle. Microscopically detectable piroplasm parasitaemias were detected in all recipients after inoculation. One splenectomised recipient developed a moderate clinical reaction, accompanied by a moderate schizont parasitosis, but recovered spontaneously, confirming persistence of schizonts in some T. parva carrier animals. By contrast, a T. parva piroplasm infection, persisting in a treated recovered splenectomised bovine, in the apparent absence of circulating schizonts, was serially (consecutively) passaged in splenectomised cattle. Seroconversion occurred in all recipient cattle. With the exception of the recipient which developed a clinical reaction and circulating schizonts, none of the recipients showed any clinical signs of T. parva infection. Upon homologous sporozoite challenge with T. parva, two out of three recipient animals with only microscopically detectable piroplasm parasitaemias developed fatal T. parva infections and one recovered after exhibiting severe clinical signs. These findings confirm the stage-specific immunity in T. parva and, contrary to popular belief, the possibility of long-term maintenance of piroplasm parasitaemias in the absence of schizonts in carrier cattle. The technique of subinoculating and establishing virulent T. parva carrier infections in splenectomised cattle also provides a method whereby buffalo-derived parasite stocks may be isolated and maintained for characterisation and the preparation of sporozoite stabilates for inclusion in T. parva vaccines. CopyrightDissertation (MSc)--University of Pretoria, 2011.
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Mukolwe, Donald Lubembe. "Population genetic structure, genotypic and antigenic diversity of Theileria parva field strains from eastern and southern Africa." Thesis, University of Pretoria, 2019. http://hdl.handle.net/2263/76736.
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Theileria parva utilizes genetic diversity as a survival strategy in evasion of the host’s immune system. Hence, effective control of T. parva infections is highly reliant on understanding the extent of genotypic and antigenic diversity of T. parva in cattle-derived and buffalo-derived isolates. Thus, the aim of this study was to identify differences between cattle- and buffalo-derived T. parva field parasites from eastern and southern Africa based on antigenic and genotypic diversity, and define the population genetic structure of T. parva parasites from the two regions.
Sequence analysis of the central variable region of the sporozoite antigen gene, p67, revealed two subtypes of p67 allele type 1, an allele type previously exclusively associated with East Coast fever. Each subtype was unique to parasites from eastern and southern Africa, thus differentiating the p67 allele type 1 population responsible for Corridor disease in South Africa from that which occurs in East Africa. The other three p67 allele types (2, 3 and 4) were detected only from buffalo-derived T. parva parasites from buffalo and Corridor disease cases. Sequences of regions containing CD8+ T-cell epitopes in ten schizont antigens, designated Tp1 to Tp10, showed epitope variants in Tp1, Tp2, Tp4, Tp5 and Tp9, where Tp2 and Tp5 had the most and least variants respectively. Tp1, Tp2 and Tp9 had variants that were common in cattle- and buffalo-derived parasites from the two regions investigated. Variants on the immunodominant Tp249-59 and Tp250-59 epitopes were only identified in buffalo-derived parasites from South Africa, while one variant of Tp1214-224 was common in parasites from the two regions. The significance of Tp4 and Tp5 in immunity is not known and the effects of natural variants of Tp9 epitope on CTL recognition have not been reported. MS19 and ms5 loci were the most and least diverse respectively, and buffalo-derived T. parva parasites showed high levels of genetic diversity. Parasites associated with Corridor disease in South Africa and East Coast fever in eastern Africa had distinguishing allelic profiles on three loci (MS8, MS19 and MS33). Individual populations from the two regions were in linkage equilibrium (VDVeterinary Tropical Diseases
PhD
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Geysen, Dirk. "The application of molecular biology techniques to analyse diversity in Theileria parva populations in Zambia." Thesis, Brunel University, 2000. http://bura.brunel.ac.uk/handle/2438/5303.
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Theileria parva is a complex protozoan parasite causing East Coast fever in Eastern and Central Africa. Vaccination using live parasites is an effective control measure and has been used in Zambia based on locally isolated and introduced T. parva stocks. Diversity among T. parva populations was investigated in parasites from two Zambian provinces with different disease epidemiologies and control histories. Isolates from the pre-vaccination era, local and exotic stocks used for vaccination, and one recent field isolate were cloned and passaged in vitro to study genomic stability over time. The results of the data from three genome-wide probes indicate a marked homogeneity and stability among the Zambian isolates in contrast to East African isolates. Results from Southern blot profiles and the polymorphic immunodominant molecule (PIM) sequence analysis suggest a common origin for the Zambian isolates from the pre-vaccination era, except for one isolate (Zam5) from Southern Province. This isolate showed characteristics suggesting a buffalo origin. Assays for genotype characterisation were developed using five allelic markers. Multilocus characterisation revealed identical profiles in a recent Zambian isolate from Southern Province and two components of an exotic cocktail vaccine, indicating the escape of one of the vaccine stocks in the field. Characterisation of T. parva field populations by RFLP-PCR assays after immunisation revealed the presence of dominant genotypes from those that had been used for vaccination. Circumstantial evidence for the involvement of one of the exotic vaccine parasites in epidemics in Southern Province is presented and a hypothesis formulated for the rapid spread of this genotype. Analysis of the characterisation data suggested the existence of two groups of T. parva parasites of different origin. The classic T. parva group, characterised by a dimorphism of the p150, p104 and p32 loci and the absence of a p67 insert and a buffalo-derived group which showed a polymorphism of p150, p104 and p32 and the presence of a p67 insert. There is evidence that recombination occurs, resulting in parasites that have characteristics of both groups. The relevance of these recombinant parasites in the epidemiology of the disease seems low. Characterisation of larger samples from areas of regular buffalo-cattle contact is necessary to clarify this. Sequence analysis of the most discriminative locus (PIM) was undertaken and gene conversion could be the main mechanism generating diversity. A more appropriate nomenclature for T. parva is proposed based on the growing evidence of molecular differences among isolates and stocks.
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Bhoora, Raksha. "Molecular characterization of Babesia caballi and Theileria equi, the aetiological agents of equine piroplasmosis, in South Africa." Thesis, University of Pretoria, 2010. http://hdl.handle.net/2263/24874.
Full textAbstract:
In an attempt to develop quantitative real-time PCR (qPCR) assays for the detection of equine piroplasms, sequence heterogeneity in the V4 hypervariable region of the 18S ribosomal RNA (rRNA) gene sequences within both Theileria equi and Babesia caballi from South Africa was discovered. A molecular epidemiological survey of the protozoal parasites that cause equine piroplasmosis was therefore carried out using horse and zebra samples from different geographical locations around South Africa. We evaluated the ability of a recently developed T. equi-specific qPCR assay in detecting all T. equi 18S rRNA variants identified in South Africa. We further present the first report on the development and application of a TaqMan minor groove binder (MGB™) qPCR assay, targeting the 18S rRNA gene, for the detection of B. caballi infections in equine blood samples. Despite the ability of the 18S rRNA T. equi- and B. caballi-specific qPCR assays to detect all known 18S rRNA gene sequence variants thus far identified in South Africa, the existence of as yet undetected variants in the field cannot be overlooked. Other qPCR assays targeting alternative genes could be developed which, used in conjunction with the 18S rRNA qPCR assays, may provide better confirmation of test results. A T. equi-specific qPCR assay targeting the equi merozoite antigen gene (ema-1) was recently developed for the detection of T. equi parasites in the midgut of Rhipicephalus (Boophilus) microplus nymphs. This assay was not able to detect T. equi in all South African samples that were confirmed positive by other molecular and serological assays. Sequence characterization of the ema-1 gene from South African isolates revealed the existence of variation in the regions where the qPCR primers and probes had been designed. Based on these observations, a conserved region of the ema-1 gene was selected and targeted in the development of an ema-1-specific TaqMan MGB™ qPCR assay, which was shown to have a higher sensitivity than the previously reported ema-1 qPCR assay. The rhoptry-associated protein (rap-1) gene from South African B. caballi isolates was also characterized following the failure of a B. caballi-specific competitive-inhibition enzyme-linked immunosorbent assay (cELISA) to detect B. caballi antibody in the sera of infected horses from South Africa. The genome walking PCR technique was used to amplify the complete rap-1 gene sequence from two South African B. caballi isolates. Significant heterogeneity in the rap-1 gene sequences and in the predicted amino acid sequences was found. Marked amino acid sequence differences in the carboxy-terminal region, and therefore the probable absence of the monoclonal antibody binding site, explains the failure of the cELISA to detect antibody to B. caballi in sera of infected horses in South Africa. This is the first comprehensive molecular study of the parasites that cause equine piroplasmosis in South Africa. Our results add further to the existing knowledge of piroplasmosis worldwide and will be invaluable in the development of further molecular or serological diagnostic assays.Thesis (PhD)--University of Pretoria, 2009.
Veterinary Tropical Diseases
unrestricted
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Bhoora, Raksha. "Molecular characterization of Babesia caballi and Theileria equi, the aetiological agents of equine piroplasmosis, in South Africa." Thesis, University of Pretoria, 2009. http://hdl.handle.net/2263/24874.
Full textAbstract:
In an attempt to develop quantitative real-time PCR (qPCR) assays for the detection of equine piroplasms, sequence heterogeneity in the V4 hypervariable region of the 18S ribosomal RNA (rRNA) gene sequences within both Theileria equi and Babesia caballi from South Africa was discovered. A molecular epidemiological survey of the protozoal parasites that cause equine piroplasmosis was therefore carried out using horse and zebra samples from different geographical locations around South Africa. We evaluated the ability of a recently developed T. equi-specific qPCR assay in detecting all T. equi 18S rRNA variants identified in South Africa. We further present the first report on the development and application of a TaqMan minor groove binder (MGB™) qPCR assay, targeting the 18S rRNA gene, for the detection of B. caballi infections in equine blood samples. Despite the ability of the 18S rRNA T. equi- and B. caballi-specific qPCR assays to detect all known 18S rRNA gene sequence variants thus far identified in South Africa, the existence of as yet undetected variants in the field cannot be overlooked. Other qPCR assays targeting alternative genes could be developed which, used in conjunction with the 18S rRNA qPCR assays, may provide better confirmation of test results. A T. equi-specific qPCR assay targeting the equi merozoite antigen gene (ema-1) was recently developed for the detection of T. equi parasites in the midgut of Rhipicephalus (Boophilus) microplus nymphs. This assay was not able to detect T. equi in all South African samples that were confirmed positive by other molecular and serological assays. Sequence characterization of the ema-1 gene from South African isolates revealed the existence of variation in the regions where the qPCR primers and probes had been designed. Based on these observations, a conserved region of the ema-1 gene was selected and targeted in the development of an ema-1-specific TaqMan MGB™ qPCR assay, which was shown to have a higher sensitivity than the previously reported ema-1 qPCR assay. The rhoptry-associated protein (rap-1) gene from South African B. caballi isolates was also characterized following the failure of a B. caballi-specific competitive-inhibition enzyme-linked immunosorbent assay (cELISA) to detect B. caballi antibody in the sera of infected horses from South Africa. The genome walking PCR technique was used to amplify the complete rap-1 gene sequence from two South African B. caballi isolates. Significant heterogeneity in the rap-1 gene sequences and in the predicted amino acid sequences was found. Marked amino acid sequence differences in the carboxy-terminal region, and therefore the probable absence of the monoclonal antibody binding site, explains the failure of the cELISA to detect antibody to B. caballi in sera of infected horses in South Africa. This is the first comprehensive molecular study of the parasites that cause equine piroplasmosis in South Africa. Our results add further to the existing knowledge of piroplasmosis worldwide and will be invaluable in the development of further molecular or serological diagnostic assays.Thesis (PhD)--University of Pretoria, 2009.
Veterinary Tropical Diseases
unrestricted
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Pfitzer, Silke. "Occurrence of tick-borne haemoparasites in nyala (Tragelaphus angasii) in KwaZulu-Natal and Eastern Cape Province, South Africa." Pretoria : [s.n.], 2010. http://upetd.up.ac.za/thesis/available/etd-03032010-141016/.
Full textBook chapters on the topic "Theileria parva – South Africa"
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Black, Samuel J., and Cynthia L. Baldwin. "Impact assessment of immunology and immunoparasitology research at ILRAD and ILRI." In The impact of the International Livestock Research Institute, 164–207. Wallingford: CABI, 2020. http://dx.doi.org/10.1079/9781789241853.0164.
Full textAbstract:
Abstract This book chapter assesses the research on bovine immunology and immunoparasitology conducted over 42 years, from 1973 to 2015, first at ILRAD (1973-1994) and subsequently at ILRI, which was formed by merging ILRAD and the International Livestock Centre for Africa (ILCA) in 1995. This assessment covers the approaches taken, the performance of research teams, the scientific truths uncovered, the cost-effectiveness of the research undertaken and the practical outcomes achieved, notably, the development of monoclonal antibodies (mAbs) and other tools to better define the bovine immune system. The chapter makes extensive use of citation data along with the personal reflections of scientists who participated in the research and surveys of opinion leaders in the field. The specific scientific goals and achievements of ILRI and its predecessors were as follows: making a substantive contribution to bovine immunology was realistic and has been substantially achieved, measuring the diversity of strains of Theileria parva, Trypanosoma brucei, Trypanosoma vivax and Trypanosoma congolense was realistic and has been substantially achieved, identifying mechanisms of immunity that kill parasites or limit the growth of the above parasites was realistic and has been substantially achieved, and developing an effective subunit vaccine against any of the parasites was an ambitious goal and so far has not been achieved.
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Ndungu, Sammy Gichuhi, Sebastian K. Waruri, and James M. Wanjohi. "East Coast Fever." In Advances in Environmental Engineering and Green Technologies, 195–220. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-6433-2.ch009.
Full textAbstract:
East coast fever, a disease of cattle caused by the protozoan parasite Theileria parva and transmitted by the three-host tick Rhipicephalus appendiculatus (the brown ear tick), is a major constraint to cattle production in Eastern, Central, and Southern Africa. In Kenya it is the most important tick-borne disease and a major constraint in cattle productivity. This is due to the high morbidity and mortality it causes in susceptible herds, the cost of control of the vector ticks, and the cost of treatment of clinical cases. Animals that recover from the disease also suffer from reduced productivity which can be long term. The limited distribution of the tick and the disease to only East, Central and Southern Africa also means that the market for therapeutic drugs and acaricides is small. Therefore, drug companies are not keen on funding research and development of new drug and acaricide molecules when resistance occurs.