Q Fever in Woolsorters, Belgium

To the Editor: Recent outbreaks of Q fever in the Netherlands and the United Kingdom raised public awareness about this ubiquitous bacterial disease known for decades to circulate worldwide (1–4). The disease, which ranges from a self-recovering infl uenza-like illness to pneumonia and severe meningoencephalitis, myocarditis, or endocarditis, is usually transmitted from animals to humans by airborne particles derived from contaminated feces and birth products. Clinical symptoms develop in only ≈40% of infected humans (1). In ≈1%– 2% of these persons, symptoms evolve toward the chronic form of the disease, which can be life-threatening (5). Q fever seroprevalence in the general population in Europe ranges from 2.4% to >30% in some countries in the Mediterranean region (5). Despite improved awareness during the past 3 years and geographic proximity with the Netherlands, few human cases were reported in (6). A retrospective survey of blood donors in the Netherlands showed a seroprevalence of 2.4% before the start of outbreaks (7). In France, the prevalence of the disease in the Nord-Pas-de-Calais region bordering Belgium is low and accounts for only 0.5% of Q fever cases in France (8). Seroprevalence of the general population in Belgium, although unknown, is thus probably comparable with that in neighboring countries in absence of outbreaks and is not expected to exceed 5%. We report a serologic, epi-demiologic, and microbiological Q fever survey conducted in a scouring factory that processed wool and goat hair products in Belgium. No acute Q fever episodes were previously reported by the factory workers. Data on clinical symptoms and risk factors were obtained in face-to-face interviews, and associations with seropositivity were explored by using regression analysis. Airborne dust collected inside the factory during goat hair processing (9) contained 10 2 –10 3 genome equivalents of Coxiella burnetii, the Q fever agent, per liter of air as estimated by real-time PCR Sheep wool processing generated less dust and resulted in a C. burnetii air load that never reached 10 genome equivalents/L in our analyses. No information is available about the infectivity or viability of air-suspended C. burnetii in the studied environment. Q fever serologic analysis was conducted by using an in-house ELISA for serum samples from 69 workers obtained annually during 2007–2009. Results of samples from the third year were confi rmed in parallel by using an immunofl uorescent assay (IFA) (Focus Diagnostics, Cypress, CA, USA) in the reference laboratory in Belgium and with follow-up …