Objective:

To investigate the effect of helminth and/or malaria infection on the risk of HIV infection in pregnant women and its transmission to their offspring.

Design:

A retrospective cohort study of pregnant Kenyan women and their offspring from term, uncomplicated vaginal deliveries (n= 936) with a nested case–control study.

Methods:

We determined the presence of HIV, malaria, schistosomiasis, lymphatic filariasis, and intestinal helminthes in mothers and tested for HIV antibodies in 12-24 month-old offspring of HIV-positive women. We related these findings to the presence of cord blood lymphocyte activation and cytokine production in response to helminth antigens.

Results:

HIV-positive women (n= 83, 8.9% of all women tested) were 2-fold more likely to have peripheral blood and/or placental malaria (P< 0.025) and a 2.1-fold greater likelihood of lymphatic filariasis infection (P< 0.001) compared to location-and-parity matched HIV-negative women. Women with HIV and malaria tended to show an increased risk for mother-to-child-transmission (MTCT) of HIV, although this difference was not significant. MTCT of HIV, however, was significantly higher in women co-infected with one or more helminthes (48%) verses women without helminth infections (10%, P< 0.01; adjusted odds ratio, 7.3; 95% confidence interval, 2.4–33.7). This increased risk for MTCT of HIV correlated with cord blood lymphocytes production of interleukin-5/interleukin-13 in response to helminth antigens (P< 0.001).

Conclusion:

Helminth co-infection is associated with increased risk for MTCT of HIV, possibly by a mechanism in which parasite antigens activates lymphocytes in utero. Treatment of helminthic infections during pregnancy may reduce the risk of MTCT of HIV.