Zoology and Entomology
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Browsing Zoology and Entomology by Author "Bakheit, M. A."
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Item Open Access Serology, molecular epidemiology and strain diversity of equine piroplasms in South Africa(University of the Free State, 2010-02) Moloi, Tshoanelo Portia; Cunningham, M.; Bakheit, M. A.; Latif, AbdallaEnglish: Equine piroplasmosis is a protozoan disease of horses caused by two parasites, Babesia caballi and Theileria equi. Both parasites are transmitted by ixodid ticks belonging to the genera Boophilus, Hyalomma, Dermacentor and Rhipicephalus. Equine piroplasmosis has a worldwide distribution and is endemic in tropical and sub-tropical regions, including Central and South America, Africa, Asia and Southern Europe. The economic impact of equine piroplasmosis in South Africa is assumed to be millions of Rands due to a combination of direct losses, convalescence period and incidental costs such as vaccinations, treatment and veterinary fees. There is little information on parasite strains in South Africa. The objectives of this study were to determine (i) the prevalence of equine piroplasmosis in Free State (FS) and KwaZulu Natal (KZN) of South Africa, using molecular and serological techniques, and (ii) strain variation of equine piroplasmosis parasites, namely, B. caballi and T. equi, using 18S rRNA DNA sequences analysis. Diagnostic methods used in this study include microscopy (thin blood smears), Polymerase Chain Reaction (PCR), Indirect Fluorescent Antibody Test (IFAT) and Enzyme-Linked Immunosorbent Assay (ELISA). Blood samples were collected from a total of 534 horses in the Free State and KwaZulu-Natal (444 were collected from FS and 90 from KZN). No B. caballi was detected from all samples collected from both provinces (FS and KZN) by microscopy and PCR. Of 507 serum samples tested for B. caballi by IFAT, a seroprevalence of 61% was detected. A mean value of 34% of samples was positive for T. equi using a PCR test and sero-prevalence of 94% was detected by IFAT. Fifty two percent of the 250 tested sera samples were positive for T. equi by ELISA. Together these results suggest high levels of exposure to parasites, high levels of current infections and uncertainty in current serological tests for these parasites. Sequencing and phylogenetic analysis of the 18S rRNA gene showed considerable diversity of T. equi strains in South Africa. T. equi is highly prevalent in South Africa with the parasite appearing to be more prevalent in KZN than FS. This study also confirmed the distribution of this disease as described in previous studies, and the disease was found also in the area which previously was declared disease-free. There is considerable variation in T. equi genotypes in the country and no clear phylogeographic structuring of these genotypes. These results may indicate that there is much movement of infected carrier horses within the country and even to and from other countries. B. caballi prevalence is still not clear as only IFAT seems to detect antibodies to infection by this parasite. There is a need for the development of highly sensitive assays for the detection of B. caballi, thereby enabling determination of prevalence and strain diversity studies of this parasite.