THE PERSISTENCE OF COMPLEMENT‐FIXING ANTIBODIES TO Q–FEVER (COXIELLA BURNETI) AFTER INFECTION

Abstract

Forty‐one abattoir workers who had contracted Q‐fever during epidemics at two abattoirs in New South Wales were tested for the persistence of Q‐fever complement‐fixing antibodies over a period of two years and nine months. Serum titres reached a peak at 21 to 30 days after the onset of symptoms, and remained at these levels for at least three months before declining. The maximum mean titre was 102, and after 31 months this had dropped to eight. The wide scatter of maximum titres and the varying rates of fall make it difficult to select any given titre as Indicating a diagnosis of Q‐fever in convalescent patients. However, it is considered that, after a Q‐fever‐like illness, a “convalescent” titre of 32 could be accepted as confirmatory evidence of the disease.