Trypanosoma cruzi: effect of parasite subpopulation on murine pregnancy outcome.

C3H/HeN female mice infected with distinct Trypanosoma cruzi subpopulations (RA strain [pantropic/reticulotropic] and K98 clone of the CA-I strain [myotropic]) show differences both in inflammatory compromise of the genital tract and in the outcome of pregnancy. The group of mice infected with the K98 clone show lymphomononuclear infiltrates in pelvian fat and in uterus interstitium, coexisting with the presence of T. cruzi DNA, and show moderate oophoritis, perioophoritis, and vasculitis. However, neither parasite DNA nor inflammatory foci were detected in the uterus, and only mild oophoritis was observed among RA-infected mice at mating time. Independently from the parasite subpopulation, females developed estrous 30 days postinoculation (PI), and at the same time, parasite counts were similar for K98 and for RA-infected mice. However, fertility was significantly diminished in K98-infected females. On day 14 of gestation, fetal resorptions increased in this group and cannot be attributed to hormonal disbalance because similar serum progesterone levels were found in all groups. At this time (44 days PI), parasitemia was higher in K98- than in RA-infected mice. However, resorptions were not triggered by massive infection because polymerase chain reaction failed to prove parasite DNA in resorbing fetuses. In contrast with K98 females, RA-infected mice delivered T. cruzi-infected newborns.