Pregnancy infections tied to impaired vaccine response in offspring

By Reuters Health

NEW YORK (Reuters Health) - Infants whose mothers were infected with malaria or helminths during pregnancy have impaired immune responses to standard vaccines against Haemophilus influenzae (Hib) and diphtheria (DT), according to a new study from Kenya.

The findings underscore the need for better control and prevention of parasitic infections among pregnant women, Dr. Indu Malhotra, of Case Western Reserve University in Cleveland, Ohio, and colleagues write.

"Deworming campaigns must be directed toward pregnant mothers, infants, and young children to improve response to vaccination," they write in a January 15 online report in PLOS Neglected Tropical Diseases.

The researchers tested 450 Kenyan women for malaria, schistosomiasis, lymphatic filariasis (LF), and intestinal helminths. An "overwhelming" 79% of the women were infected, 44.7% with LF, 33.8% with hookworm, 32.4% with schistosomiasis, and 27.6% with malaria.

After standard vaccinations at six, 10, and 14 weeks, the newborns were followed twice a year until age 36 months and tested for levels of immunoglobulin G (IgG) against Hib, DT, Hepatitis B (Hep B), and tetanus toxoid (TT) at each time point.

Infants whose mothers had had malaria, LF or hookworm infections during pregnancy had significantly lower post-vaccination levels of Hib-specific IgG, even after controlling for maternal age, parity, education, income and childhood parasitic infections, the researchers found.

Schistosomiasis alone in the mother had no effect on vaccine-specific IgG levels, while malaria, LF, schistosomiasis and hookworm had no effect on DT, Hep B, or TT.

Infants born to mothers with three or more infections had significantly lower DT-specific IgG at six and 12 months, though this was not the case when mother had had fewer infections.

"While the observed lower levels of antibody response may not obviate the individual protective effect of vaccination, these lower levels of immune response could contribute to persistent pathogen carriage, leading to continuing disease transmission among affected communities," Dr. Malhotra and colleagues write.

They add, "If vaccine efficacy is to be ensured in disease-endemic developing countries, eradication of chronic helminthic infections may be imperative to the overall success of global vaccination efforts."

This research was supported by the National Institutes of Health, the Bill and Melinda Gates Foundation, and the Clinical and Translational Science Collaborative of Cleveland. The authors report no disclosures.

SOURCE: http://bit.ly/1E22HXx

PLoS Negl Trop Dis 2015.

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