Q fever and HIV infection

Abstract

Objective: To study the frequency of Q fever in HIV-infected individuals.

Design: A seroprevalence study.

Setting: French National Reference Centre for Rickettsial Agents, Marseille, France.

Patients and methods: Five out of the 68 hospitalized cases of Q fever diagnosed in 1987-1989 were also HIV-infected and are described here. Sera from a blood-donor bank (n = 925) and from HIV-positive individuals selected at random, irrespective of clinical or immunological status (n = 500) were tested for Q fever.

Results: Comparisons of the two groups showed a statistically significant difference (2.4 versus 0.8%; Fisher's exact test) at the diagnostic dilution 1:200 and at the dilution considered positive for seroprevalence study (1:1000).

Conclusions: Using the estimated incidence of HIV infection in Marseille, the number of Q fever cases in 1987-1989 was 13 times higher and the clinical expression more frequently symptomatic in the HIV-positive population than in the general one. The prevalence:seroprevalence ratio for Q fever was 1.37% in the HIV-positive group and 0.36% in the blood-donor group. Sera positive for Q fever were confirmed by Western blot analysis in order to minimize cross-reaction. Transmission of Q fever appears to be more frequent in HIV-positive individuals than in the general population; this is not surprising, since Coxiella burnetii lives in the phagolysosome, like other micro-organisms described in immunocompromised hosts. Q fever should be added to the spectrum of diseases that occur more frequently during HIV infection.