A STUDY OF AN ENZOOTIC FOCUS OF SHEEP BABESIOSIS (BABESIA-OVIS, BABES, 1892)

Morbidity and mortality due to Babesia ovis in sheep flocks grazing in an enzootic area of Israel occur yearly, about 2 weeks after detectio n of adult Rhipicephalus bursa ticks on the animals. Disease incidence peaks in May, but lasts throughout the active period of the adult tic ks in the spring-summer months of April-July. No clinical cases of bab esiosis have been registered during the active period of the preimagin al stages of R. bursa, from October to February. Incidence of parasita emia during the spring-summer months was variable, ranging between 2 a nd 25%. However, in the winter months the incidence of parasitaemia in hoggets increased considerably, reaching 4-60% of the animals. A posi tive serological response to B. ovis was found in 84.5% of the hoggets and 88.9% of the ewes. In ewes, the prevalence of the serological res ponse showed no marked seasonal variations. Colostral sera of 67.5% an d 75% of the ewes and hoggets, respectively, were serologically positi ve for B. ovis. No antibodies were detected in the sera of lambs less than 3-4 months of age. The epizootiology of sheep babesiosis appears to differ from that of bovine babesiosis.