Pregnancy outcomes of Q fever: prospective follow-up study on Reunion island.
BACKGROUND
Q fever has been associated with perinatal complications. We conducted a prospective follow-up study to assess both the incidence of adverse pregnancy outcomes (APOs) associated with Coxiella burnetii infection and the contribution of Q fever to APOs.


METHODS
Between May 1 and October 31, 2013, within the regional perinatal health care centre of Saint Pierre, Reunion island, we investigated unexplained miscarriages, stillbirths, preterm births or small-for-gestational age children. Seropositivity for C. burnetii antibodies was defined using indirect immunofluorescence for a phase 2 IgG titre ≥1:64. Acute Q fever was defined for a high phase 2 IgG titre ≥1:256 (compatible with recent or active infection) or the detection of C. burnetii genome in miscarriage products and placentas. Incidence rate ratios (IRR) for Q fever related APOs (taken as a composite outcome or individually) were assessed using Poisson regression models for dichotomous outcomes controlling major confounders.


RESULTS
Over a 6-month period, 179 pregnant women suspected or diagnosed with an APO were investigated for Q fever, of whom 118 met the definition for an APO. Of these, 19 were seropositive and 10 presented a profile indicative of an acute infection. For three women with an acute Q fever, the chronology between the onset of infection, the APO (2 miscarriages, 1 preterm birth) and the seroconversion suggested causality in the pathogenesis. The cumulative incidence of Q fever related APOs was estimated between 2.2‰ and 5.2‰, whether causality was required or not. Both C. burnetii exposure and acute Q fever were independently associated with APOs (IRR 1.55, 95% CI 1.31-1.84; IRR 1.47, 95% CI 1.15-1.89, respectively).


CONCLUSIONS
In the endemic context of Reunion island, acute Q fever may lead to APOs. To limit the burden of Q fever on reproduction, pregnant women should be kept away from farms and avoid direct contact with ruminants.
['Mboussou|Yoan|Y|', 'Jaubert|Julien|J|', 'Larrieu|Sophie|S|', 'Atiana|Laura|L|', 'Naze|Florence|F|', 'Folio|Christine|C|', 'Randrianaivo|Hanitra|H|', 'Bertolotti|Antoine|A|', 'Picot|Sandrine|S|', 'Robillard|Pierre-Yves|PY|', 'Boukerrou|Malik|M|', 'Gérardin|Patrick|P|http://orcid.org/0000-0002-3276-5919']
D000293:Adolescent D000328:Adult D000907:Antibodies, Bacterial D016997:Coxiella burnetii D004269:DNA, Bacterial D005260:Female D019084:Fluorescent Antibody Technique, Indirect D005500:Follow-Up Studies D006801:Humans D015994:Incidence D010920:Placenta D011247:Pregnancy D011251:Pregnancy Complications, Infectious D011256:Pregnancy Outcome D011446:Prospective Studies D011778:Q Fever D060888:Real-Time Polymerase Chain Reaction D012189:Retrospective Studies D017508:Reunion D055815:Young Adult
Pregnancy Q fever Incidence Coxiella burnetii Miscarriage Stillbirth Immunofluorescence Cohort studies Serology Zoonosis