Control of cowdriosis and observations on diseases of sheep in the Niayes region of Senegal

Abstract

Sheep originating from an heartwater-free area were immunized by the infection and treatment method, using long-acting oxytetracycline. The animals were then exposed, together with control sheep to natural infection in an enzootic area. Tick counts were made to monitor the infestation and establish a correlation between infestation by certain tick species, in particular Amblyomma variegatum, and the occurrence of cowdriosis. In some cases of death associated with ehrlichiosis and anaplasmosis in the group immunized against cowdriosis, groups of Cowdria ruminantium were found in smears of the cerebral cortex, which leaves question marks as to the real nature of immunity to cowdriosis. Furthermore, these losses show the necessity of an integrated approach to the control of diseases of livestock in a given area. The presence of Rhipicephalus e. evertsi, formerly absent from this area, was significant in this respect.