High seroprevalence to Bartonella quintana in homeless patients with cutaneous parasitic infestations in downtown Paris

Bartonella quintana infections have recently been reported in homeless pati ents. We prospectively studied the prevalence of and the factors associated with a positive serology to B quintana in the homeless population of downt own Paris. Toe following data were recorded: ongoing cutaneous parasitic in festation, years of homelessness, living status, previous episodes of body pediculosis and scabies, alcoholism, intravenous drug use, known immunodepr ession (including undernutrition and known HN infection), and contacts with animals. B quintana serology was performed in 57 patients and in 53 age- a nd sex-frequency-matched downtown Paris volunteer blood donors. Thirty-one patients (54%; 95% confidence interval [CI], 41%-68%) had a positive B quin tana serology as compared with 2% in the control group (P <.0001); 8 of 57 patients (14%; 95% CI: 6%-26%) had a serologic profile of an evolving infec tion. Age and years of homelessness were independently associated with a po sitive B quintana serology with adjusted relative risks (RRs) of 2.9 (95% C I, 1.4-5.9) for age 40 years and older and 1.7 (95% CI, 1.1-2.7) for years of homelessness 3 or more. Our results suggest a high prevalence of past an d recent infections with B quintana in the downtown Paris homeless populati on with cutaneous parasitic infestations.