The relationship among injury, leucocyte count and molecular diversity of theileria in zebra’s in Naivasha-Kenya
King’ori, Edward Mutethia
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Understanding the interrelationships between injury, infection and diversity of Theileria in a zebra population may illuminate the mechanisms by which injuries influence the course of latent infections, and may be an important factor to be considered during therapy of injured animals. Currently, the molecular diversity of Theileria species that are circulating in Kenyan free living common zebras is unknown and the effect of anthropogenic induced injuries on Theileria diversity and infection patterns are poorly known. Moreover, zebras are considered maintenance or reservoir hosts for Theileria equi infecting domestic equines such as donkeys and horses. The objectives of this study were; to examine and evaluate molecular genetic diversity of Theileria sp infecting injured and healthy free living zebra’s from different localities in Naivasha. Examine the leucocyte differential cell count in injured and healthy zebra. Evaluate the influence of Theileria infection on the leucocyte differential count in zebra. Theileria infecting Zebra was detected and characterized using PCR amplification and sequencing of the 18S ribosomal gene from parasite DNA extracted from host blood. Leucocyte differential of injured and healthy zebra was examined using microscopy of blood smears. All 81 zebras examined yielded positive PCR results using gel electrophoresis. Seventy-nine clean sequences were obtained and blast results were closely matched Theileria equi. There were 3 Theileria equi haplotypes circulating among zebra in Naivasha. Haplotype 2 was the most common Theileria haplotype infecting zebras with a prevalence of 90.63% in injured animals and 66.67% in non-injured animals. There was genetic differentiation in terms of the frequency of haplotypes infecting injured compared to non-injured Zebra (FST=0.732, P<0.0001). Injured animals had a lower haplotype diversity for Theileria equi compared to the non-injured (Haplotype diversity for non-injured =0.533, Injured =0.175). Injured zebras had a higher median percent of neutrophils than non-injured zebras (median neutrophil was 64 and 37 in injured and non-injured respectively, P=0.001). The percent of lymphocytes on the other hand was lower in injured zebras compared to uninjured animals (median was 35 and 53 for injured and not injured respectively, P=0.001). Similarly, the percent of Eosinophils and monocytes were reduced in injured animals compared to non-injured animals (median=0 and 2 for eosinophils and 0 and 2 for monocytes respectively, P=0.001). This study shows a lower genetic diversity of Theileria equi infecting zebra compared to other equine populations studies so far. The low genetic diversity is consistent with the low genetic diversity in injured zebra and suggests that the influence of injuries in this population is profound.