Maternal-fetal Chagas disease transmission still problematic

By Piriya Mahendra, medwireNews Reporter

The incidence of Chagas disease, otherwise known as Trypanosoma cruzi infection, is still high in pregnant women in Bolivia, researchers say.

Screening for Chagas disease, transmitted by the Triatominae subfamily of insects, should be routinely performed in pregnant women at risk for giving birth to infected babies in regions or countries without transmission of T. cruzi but inhabited by migrants from endemic countries, Jean-Phillippe Chippaux (Institut de Recherche pour le Développment, Paris, France) and team recommend.

There is currently no vaccine against the infection and prevention efforts are focused mainly on controlling the vector Triatoma through use of insecticide.

Chippaux et al found that of the 15,767 women who gave birth in three hospitals in the city of Santa Cruz de la Sierra between 2006 and 2008 and participated in serum screening, 3725 (23.6%) were serologically positive for T. cruzi.

Logistic regression analysis revealed that the incidence of congenital T. cruzi transmission was 0.8%, corresponding to a total of 125 infected newborns of the overall cohort. As reported in Acta Tropica, the rate of vertical transmission was 3.4% in all three hospitals included in the study.

Overall, 3.9% of serologically positive women refused blood sampling in their newborn for the diagnosis of infection with T. cruzi. The refusal rate differed significantly between the three hospitals in the city, with 39 women attending the Percy Boland Rodriguez hospital refusing compared with only two at the Hospital Francés and one at the Caja Nacional de Salud.

The authors point out they made the diagnosis of Chagas disease at birth and not during the first year of life, which may have led to them underestimating the true incidence of the disease. They also note that "the study was not designed to evaluate missed opportunities and the performance of samples according to periods of sampling."

Chippaux and team explain: "Mothers were urged to return for checking but very few actually came back, and this leads to considerable bias that prevents us from mentioning these partial results."

Nonetheless, they conclude: "Health authorities should develop screening for congenital Chagas disease by promoting the implementation of techniques for serological and parasitological diagnosis of infection by T. cruzi and training of health staff."

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