Congenital infection by Trypanosoma cruzi in an endemic area of Chile: a multidisciplinary study

Background: This study investigated the prevalence of Chagas disease (ChD) in pregnant women in Choapa Province (IV Region, Chile) and the vertical transmission of Trypanosoma cruzi. Method: ELISA and IFI IgG for ChD was performed for the pregnant women. PCR for T. cruzi was done for all chagasic mothers and their newborns. The congenital infection was confirmed by serial positive PCR and/or ELISA or IFI IgG after age of nine months. The placentas of mothers, with and without ChD, were submitted for histopathology and immunohistochemical study. Results: From 4831 deliveries in 2005 - 2009 with a serological coverage of 88.6%, it was established that 147 cases (3.4%) had ChD. More than 80% of the pregnancies had a physiological evolution and 90% of the newborn were term. Congenital transmission was demonstrated in six children (4.7%) of the 127 newborn studied by serial PCR (at birth and/or between 3 - 18 months) and/or ELISA or IIF IgG after age nine months. Most of congenital cases were asymptomatic (67%). The histopathology shows edema, necrosis, fibrinoid deposit in the placentas of 28 of 29 chagasic mothers. In three cases the immnunochemistry demonstrated a decrease in actin expression in trophoblast cells. In one congenital case amastigote nests was observed. Conclusions: These results indicate that T. cruzi infection in pregnant women and vertical transmission in Chile are still prevalent. For this reason it is important to propose control measures in endemic areas of the country.