An understanding of the susceptibility of different species and breeds of animals to trypanosomosis in sub-Sahara Africa would facilitate the formulation of effective control measures against the ravaging spread of African animal trypanosomosis. In this study, the prevalence of Trypanosoma species in apparently healthy Nigerian breeds of sheep was determined together with the evaluation of the Packed Cell Volume (PCV) as an indicator of the severity of infection. Blood samples of 243 sheep, including 97 West African Dwarf (WAD), 60 Yankassa, 62 Ouda, 19 Balami, and five Crossbred, were screened for trypanosomes by the Haematocrit Centrifugation Technique (HCT) and species-specific Polymerase Chain Reaction (PCR) technique. In none of the blood samples were trypanosomes detected by the HCT whereas 35.4% of the samples were positive by the PCR technique. The overall prevalence of trypanosomes by the PCR technique was T. vivax (23.05%), T. congolense Savannah (13.38%), T. congolense Forest (7.82%) and T. brucei brucei (4.53%) while the breed specific prevalence was WAD (25.8%), Yankassa (36.7%), Ouda (43.5%), Balami (47.4%) and Crossbreeds (60%). Generally, the mean PCV of infected sheep was slightly (p > 0.05) lower than that for the non-infected except for the WAD breed.
This study revealed that sub-clinical ovine trypanosomosis was endemic in the study area with Trypanosoma vivax being the most prevalent. The findings thus suggest that sheep may play a significant role as a reservoir of trypanosomes to other species of domestic animals and, as such, should be included in trypanosomosis control programmes.
Key words: Trypanosome species, Sheep, Polymerase Chain Reaction (PCR), Nigeria
|
