Prevalence of cystic echinococcosis and diversity of echinococcus granulosus infection in sheep in Olokurto Division, Narok County, Kenya

Abstract

Cystic Echinococcosis is a serious zoonotic disease caused by Echinococcus granulosus species complex. This research study was conducted to determine the level of infection of the disease in sheep in Olokurto division, Narok County, Kenya. The study area was divided into five locations and 180 sheep selected randomly from each location were inspected for infection. Sample collection was conducted in Likia slaughter house. The carcass of each sheep was inspected carefully for the presence of hydatid cysts, infection and the organs infected and the number of cysts was recorded. The sheep identification number and sex, and age as determined by dentition were also recorded. Hydatid cysts collected were preserved in 70% ethanol and transported to the laboratory for analysis. In the laboratory, cysts size and volume of hydatid fluid were measured, microscopic examination of hydatid fluid was performed to determine cysts fertility, and species identification was determined following restriction digests of amplified PCR products which targeted the NADH dehydrogenase subunit 1 (nad-1) gene. Overall prevalence was 16.0% (144/900), infection rates in the five sampling sites were significant (P<0.05), with the liver being the most infected organ (50.7%), followed by the lungs (36.8%), while mixed infections involving the liver and the lungs were detected in12.5% of the sheep sampled. PCR/RFLP results revealed that all strains were E. granulosus sensu stricto which means that the genotype is G1 (genotype1). The cysts were examined under the microscope to determine fertility, out of the 343 hydatid cysts collected and examined, 62.1% of the hydatid cysts were fertile, 35.2% were sterile while 2.7% were calcified. Lung cysts were found to be more fertile (73.02%) compared to liver cysts (53.4%). There was a direct relationship between age, number and size of hydatid cysts as the number and size of the cysts increase with increase in age of the sheep. Since all strains were G1 which is particularly pathogenic to humans, it is importance to control the disease