Household outbreak of Q-fever pneumonia related to a parturient cat.

An outbreak of febrile respiratory disease occurred over 11 days among thirteen adults in Nova Scotia, all members of an extended family and their friends. Signs of illness included bradycardia at the same time as fever, palatal petechiae, and rapidly enlarging bilateral pulmonary infiltrates. Ten of the patients had a four-fold rise in antibody to phase-2 Q-fever antigen as determined by complement fixation on acute and 4-week-convalescent serum samples. Six children of the extended family for whom a four-fold titre rise was shown had slight or no disease. Investigations showed that the illness related to having entered the home of four of the patients on 1 of 2 consecutive days. On the first day the family cat, subsequently found to have antibody to Q fever, gave birth to kittens which she nursed in a basket kept inside the entry way. Q fever has been associated with parturient cattle, sheep, and goats but family pets, particularly cats, have not previously been implicated in human illness.