The value of skin test in Q fever convalescents and vaccinees as indicator of antigen exposure and inducer of antibody recall.

The skin test (ST) with Q fever chemovaccine revealed more positive reactors than the serological examination by microagglutination (MA) test among humans, who had suffered from Q fever one to eleven years ago or who had been vaccinated with Q fever chemovaccine from three months to four years ago. When examining the sera harvested either at skin-testing or two weeks thereafter by MA test, seroconversion or rise in antibody titres were found to both main Coxiella burnetii (C. b.) antigens. The rise or appearance of antibody response was similar in Q fever convalescents and vaccinees, in the latter occurring more often in ST positive than in ST negative individuals. Results of ST at different postvaccination (p.v.) intervals corresponded well to those of lymphocyte transformation (LT) test, but not to those of inhibition of leukocyte migration ( ILM ) test.