Strategies for early detection of chronic Q-fever: a systematic review

BACKGROUND: Chronic Q-fever, a condition with high morbidity and mortality, may develop after an acute infection with Coxiella burnetii (acute Q-fever). Several strategies have been suggested for early detection of chronic Q-fever, focusing on follow-up of known acute Q-fever patients and detection of asymptomatic or unknown chronic infections. As there is no international standard or consensus, the aims of this study were to summarise the available literature and assess the evidence for different follow-up and screening strategies. DESIGN: We conducted a systematic review by searching PubMed and Embase. Twenty articles were included, of which fourteen only provided information on follow-up of known acute Q-fever cases, four presented data on identification of previously unknown C. burnetii infections, and two had information on both topics. RESULTS: The conversion rate of acute to chronic Q-fever ranged from 0 to 5.0%. Most studies advised serological follow-up of acute Q-fever patients, but without consistent advice on optimum timing and duration. The recommendation to use echocardiography for all acute Q-fever patients to detect valvular damage remains controversial. Screening of high-risk patients in an outbreak setting is advised by studies investigating such strategy. CONCLUSIONS: There is sufficient evidence to support serological follow-up of all known acute Q-fever patients at least once during the first year following the acute infection, and more frequently in patients with known risk factors for chronic disease, such as heart valve- or vascular prosthesis. Screening of risk groups should be considered in outbreaks of Q-fever