The congenital transmission of
Chagas disease is associated with an increase in
parasitemia during pregnancy, maternal and fetal immunity, and populations of Trypanosoma cruzi. In this study, the
biological behavior of TcI and TcV (isolated from a human congenital case) strains and their potential for experimental congenital transmission were evaluated in female BALB/C mice.
Parasitemia was estimated by fresh blood examination, semiquantitative microhematocrit, and hemoculture, while congenital transmission was evaluated by culture in the liver infusion
tryptose medium and by polymerase chain reaction (PCR) of the pups' tissues on postnatal day 7 and of the pups' blood sample at 30 days after birth.
Infection was detected in 100 % of the females. Both strains showed subpatent
parasitemia, which was higher for TcV
infection. The presence of amastigote nest was detected only in an animal infected with TcI. The inflammatory process was more frequent (p = 0.001) in the tissues of the animals infected with TcV (58.6 %) than TcI (31.1 %). The fertility rates of females mated after 35 days postinfection were similar (90 % for TcV, 88.9 % for TcI; p = 0.938).
Parasitemia did not change during pregnancy. The average number of pups/female was greater (p = 0.03) in mice with TcV
infection (8.30) than in those with TcI
infection (4.78). Congenital transmission was detected exclusively by PCR in 50.9 % of the pups, 46.6 % for TcV and 58.1 % for TcI. The PCR positivity for TcI was higher in the blood than in the tissue (p = 0.003). These results demonstrate the T. cruzi experimental congenital
infection associated with subpatent maternal
parasitemia of TcI and TcV.