Maternal Geohelminth Infections Are Associated with an Increased Susceptibility to Geohelminth Infection in Children: A Case-Control Study

Background Children of mothers infected with soil-transmitted helminths (STH) may have an increased susceptibility to STH infection. Methods and Findings We did a case-control study nested in a birth cohort in Ecuador. Data from 1,004 children aged 7 months to 3 years were analyzed. Cases were defined as children with Ascaris lumbricoides and/or Trichuris trichiura, controls without. Exposure was defined as maternal infection with A. lumbricoides and/or T. trichiura, detected during the third trimester of pregnancy. The analysis was restricted to households with a documented infection to control for infection risk. Children of mothers with STH infections had a greater risk of infection compared to children of uninfected mothers (adjusted OR 2.61, 95% CI: 1.88–3.63, p
Author Summary Soil-transmitted helminths (intestinal worms) are among the most common childhood infections worldwide and are a significant cause of morbidity particularly among poor populations living in developing countries. The potent immune modulatory effects of these parasites have been suggested to be a determinant of the epidemiological distributions of other infectious diseases (e.g., HIV and tuberculosis) and allergy. There is strong epidemiological evidence that some individuals have an increased susceptibility to re-infection after treatment and the mechanisms underlying this are not well understood. A possible explanation is that in utero exposure to maternal STH infections may increase the risk of infection during childhood, but, as far as we are aware, no published study has addressed this hypothesis for STH infections in humans. In this study, we evaluated whether children of mothers infected with STH infections have a greater risk of infection when compared to children of uninfected mothers. We also examined whether this increased susceptibility to infection might occur through the tolerogenic effects of increased levels in the systemic circulation of the immune regulatory cytokine IL-10, in early life. Our data provide evidence that maternal STH infections predispose children to infections with STH parasites, and this effect was associated with elevated levels of IL-10 in newborn blood.