Specific prophylaxis of enzootic chlamydial ovine abortion

A vaccine against chlamydial ovine abortion was prepared according to an original method and experimentally applied to more than 500,000 animals in large breeding units. The vaccine induced a considerable seroconversion (as demonstrated by complement fixation tests) and reduced by 3--5 times the damage due to chlamydioses. Vaccination of primiparous ewes, followed by 2--3 annual revaccinations, gave good results, conferring resistance on the vaccinated animals.