Q Fever during pregnancy: a cause of poor fetal and maternal outcome.

Q fever is a worldwide zoonosis caused by Coxiella burnetii. Q fever may be present as an acute or a chronic infection and can be reactivated during subsequent pregnancies. Although its exact prevalence remains unknown, it is likely that the number of cases of Q fever in pregnant women is underestimated. During pregnancy, the illness is likely to be asymptomatic, and diagnosis is based on serology. Acute infection results in appearance of IgM and IgG antibodies mainly directed against the avirulent form of C. burnetii (phase II). Chronic Q fever results in particularly high level of IgG and IgA antibodies directed against both virulent (phase I) and avirulent (phase II) forms of the bacterium. Q fever may result in adverse pregnancy outcome, including spontaneous abortion, intrauterine growth retardation, oligoamnios, intrauterine fetal death (IUFD), and premature delivery. Obstetric complications occur significantly more often as C. burnetii infects the patient at an early stage of her pregnancy. Occurrence of IUFD is correlated with the presence of placental infection by C. burnetii and might be the consequence of direct infection of the fetus. The mother is exposed to the risk of chronic Q fever and endocarditis with potential fatal evolution. Long-term cotrimoxazole therapy prevents from placental infection, IUFD, and maternal chronic Q fever. Such treatment should be used to treat pregnant women with Q fever. Women with previous history of Q fever should have a regular serological follow up. Obstetricians' knowledge about Q fever must be improved.