Vaccination of cattle against Q-fever.

Formalin-killed phase I C. burneti organisms containing the protective antigenic component were used for vaccination of heifers against Q fever. None of the vaccinated heifers contracted Q fever, whereas 8 out of 12 (66.6%) control, non-vaccinated heifers became infected when exposed to infection for 3 months in the breed of naturally infected dairy cows. In the vaccinated cattle C. burneti was detected immediately post partum neither in the placenta nor in the colostrum. No shedding of C. burneti in milk has been found so far during 3 years of post-vaccinal observation period. For detecting Q fever antibodies in the blood of vaccinated as well as naturally infected animals MAR was found more sensitive than CFR.