Abstract

Sera collected from dairy farmers, their families and farm workers, slaughtermen, artificial inseminators, veterinarians, and a group of doctors and civil servants with no direct connexion with farming were examined for evidence of Q fever or leptospirosis. One thousand and fifty-two sera examined for Q fever yielded 26% of positive results with titres of complement-fixing antibody through 1 in 4 to 1 in 128 and over. On the other hand, 876 sera examined for agglutinating antibody to various leptospirae showed only 0·5% of positive titres of 1 in 80 and over. None of the individuals with positive sera for Q fever had ever been ill with anything resembling Q fever or could remember any ill health in the past; this suggests subclinical infection. One farmer with a high titre against L. copenhageni (icterohaemorrhagiae) gave a history of a recent febrile illness very suggestive of acute leptospirosis. Infection due to leptospirae appeared to be very much less common than that due to C. burneti.