Association between human brucellosis and adverse pregnancy outcome: a cross-sectional population-based study

To investigate the association between the incidence of human brucellosis (HB) and adverse pregnancy outcomes (APOs), a population-based, cross-sectional aggregate data study was conducted in Israel between 2010 and 2014. HB-endemic localities were matched by ethnicity, population size and socioeconomic status to localities with a low incidence of HB. We compared APO rates in high-incidence vs low-incidence localities. The primary outcome was intrauterine fetal demise (IUFD). Secondary outcomes were premature birth (less than 37 weeks), early or threatened labour and poor fetal growth. APOs are expressed as events per 1,000 live or dead births. Eleven high-incidence localities, all Arab villages or cities, were matched to 11 low-incidence localities. Localities were well-matched with regard to the matching criteria, fertility indices, health insurance access and education, but were imbalanced geographically. All defined APOs occurred significantly more frequently in the high-incidence localities. The associations translated to an absolute increase of 3.6 cases of IUFD (95% CI 1.6-5.3), 11.7 preterm births (4.8-18.3), 6.6 cases of early or threatened labour (2.2-10.9) and 7 cases of poor fetal growth (3-10.8), per 10,000 live or dead births. Owing to a geographic imbalance between high- and low-incidence localities, we conducted an analysis restricted to Southern localities of Arab Bedouins showing a significant association between yearly HB incidence and IUFD incidence, odds ratio 1.05 (1.03-1.06). HB incidence is epidemiologically linked to serious pregnancy complications. Early detection of infection through active surveillance during pregnancy followed by appropriate treatment should be evaluated as additional public heath strategy in endemic settings.