[Combined use of serological tests for the purpose of the diagnosis and study of Q-rickettsiosis].

The combined use of the complement fixation test, the indirect immunofluorescent test and the ring precipitation test with C. burnetii antigen greatly enhances the effectiveness or serological study, as it allows not only to find out the spread of infection among population more completely, but also to differentiate, to a certain extent, "fresh" infectious process from immunological trace reaction. The arguments are presented in favor of introducing the antigen of C. burnetii, phase I, into practice, especially in surveying the sera of farm animals.