Detailed analysis of health status of Q fever patients 1 year after the first Dutch outbreak: a case-control study.

Background: Q fever is a zoonosis caused by the obligate intracellular bacterium Coxiella burnetii. The two long-term complications, after primary infection, are chronic Q fever in ∼1% of patients, and a chronic fatigue syndrome in 10-20%. However, the existence of a protracted decreased health status after Q fever remains controversial.
Aim: To determine the health status of the patients of the Q fever outbreak in The Netherlands in 2007, 1 year after primary infection.
Design: Cross-sectional case-control study.
Methods: Health status of the patients from the 2007 Dutch Q fever outbreak was compared to age-, sex- and geographically matched and Q fever seronegative controls. Health status of both patients and controls was assessed with the Nijmegen Clinical Screening Instrument (NCSI).
Results: Fifty-four Q fever patients provided 34 years of age- and sex-matched controls from the same neighbourhood. Eleven controls had positive Q fever serology and were excluded. Q fever patients had significantly more problems on the subdomains of symptoms and functional impairment. Overall quality of life was decreased in both patients and controls, 59% vs. 39%, respectively, ns). Severe fatigue levels were present in 52% of patients vs. 26% in controls (P < 0.05).
Conclusion: These data support a sustained decrease in many aspects of health status in Q fever patients in The Netherlands, 1 year after primary infection.