[Q fever: 54 new cases from a tertiary hospital in Madrid]

To describe the epidemiological and clinical characteristics of Q fever in an urban zone of the Community of Madrid (Spain).

An observational, retrospective study was performed of a cohort of cases diagnosed of Q fever within a single center in Madrid from January 2001 to December 2008. The diagnosis of acute Q fever was made by detection of antibodies against phase II antigen by Enzyme-Linked Immunosorbent Assay (ELISA) and indirect immunofluorescence (IFA), based on isolated titer ≥ 1/80 or when they showed seroconversion or seroreinforcement. Chronic Q fever was diagnosed using antibodies against phase I with a positive value if IgG ≥ 1/800.

A total of 54 cases of Q fever in adults were diagnosed; 51 patients had acute Q fever and only 3 chronic. There was a predominance of men over > 50 years and from urban areas. The most frequent manifestation was pneumonia (54%), followed by renal failure (33%), hepatitis and fever without focality (25% in both), with concomitant infection in 37% of the cases. The clinical and serological monitoring in most of the patients were inadequate. The best response to treatment was with doxycycline in acute illness, although duration was inadequate in 10%.