Eduardo Suarez

Are maternal re-infections with Trypanosoma cruzi associated with higher morbidity and mortality of congenital Chagas disease?

Background  Comparing two surveys performed in Bolivia in 1992–1994 and 1999–2001, we reported a significant decrease in the proportions of severe and mortal forms of congenital Chagas disease. This might be due to a reduction of vectorial density (VD) in maternal residence area, raising the question of a possible causal relationship between such VD, maternal parasitaemia and prognosis of congenital infection with Trypanosoma cruzi.

Maternal infection with Trypanosoma cruzi and congenital Chagas disease induce a trend to a type 1 polarization of infant immune responses to vaccines.

Background We previously showed that newborns congenitally infected with Trypanosoma cruzi (M+B+) display a strong type 1 parasite-specific T cell immune response, whereas uninfected newborns from T. cruzi-infected mothers (M+B−) are prone to produce higher levels of proinflammatory cytokines than control neonates (M−B−). The purpose of the present study was to determine if such fetal/neonatal immunological environments could alter the response to standard vaccines administered in early life. Methodology Infants (6–7 months old) living in Bolivia, an area highly endemic for T. cruzi infection, and having received Bacillus Calmette Guerin (BCG), hepatitis B virus (HBV), diphtheria and tetanus vaccines, were enrolled into the M+B+, M+B−, M−B− groups mentioned above. The production of IFN-γ and IL-13, as markers of Th1 and Th2 responses respectively, by peripherical blood mononuclear cells stimulated with tuberculin purified protein derivative of Mycobacterium tuberculosis (PPD) or the vaccinal antigens HBs, diphtheria toxoid (DT) or tetanus toxoid (TT), as well as circulating levels of IgG antibodies against HBsAg, DT and TT were analyzed in infants. Cellular responses to the superantigen SEB were also monitored in M+B+, M+B−, M−B−infants and newborns. Principal Findings M+B+ infants developed a stronger IFN-γ response to hepatitis B, diphtheria and tetanus vaccines than did M+B− and M−B− groups. They also displayed an enhanced antibody production to HBsAg. This was associated with a type 1-biased immune environment at birth, since cells of M+B+ newborns produced higher IFN-γ levels in response to SEB. M+B− infants produced more IFN-γ in response to PPD than the other groups. IL-13 production remained low and similar in all the three groups, whatever the subjects ages or vaccine status. Conclusion These results show that: i) both maternal infection with T. cruzi and congenital Chagas disease do not interfere with responses to BCG, hepatitis B, diphtheria and tetanus vaccines in the neonatal period, and ii) the overcoming of immunological immaturity by T. cruzi infection in early life is not limited to the development of parasite-specific immune responses, but also tends to favour type 1 immune responses to vaccinal antigens.