Epidemiology of hydatid disease in Kenya: a study of the domestic intermediate hosts in Masailand.

The results are given of a study on the epidemiological significance of cattle, sheep and goats in maintaining the life-cycle of Echinococcus granulosus in Masailand, Kenya. A total of 134 (8.9%) of 1499 cattle, 146 (8.1%) of 1798 sheep and 144 (7.1%) of 2020 goats slaughtered in abattoirs in Masailand were found to harbour hydatid cysts. The frequency distribution of the hydatid cysts in each intermediate host species was over-dispersed. Of 729 cattle cysts examined 71 (9.7%) were fertile (cyst contained protoscoleces) with an average viability of 71%, 507 (69.5%) were sterile and 151 (20.7%) were calcified. Out of 810 sheep and 451 goat cysts examined 571 (70.5%) and 213 (47.0%) were fertile with respective viabilities of 88% and 86% and 143 (17.7%) and 194 (43.0%) were sterile leaving 96 (11.6%) and 45 (10.0%) sheep and goat cysts which were calcified. The greater fertility of the sheep and, to a lesser extent, goat cysts coupled with the reported greater infectivity of sheep and goat than cattle material to dogs and the common Masai practice of slaughtering sheep and goats at home, indicates that, at present, sheep and goats are the most important intermediate hosts for the maintenance of the domestic life-cycle of E. granulosus in Masailand. The incidence of hydatidosis in donkeys and the relationship of the domestic cycle to the wildlife cycle operating in the same area is unknown and requires further study.