High similarity of Trypanosoma cruzi kDNA genetic profiles detected by LSSP-PCR within family groups in an endemic area of Chagas disease in Brazil.

INTRODUCTION: Determining the genetic similarities among Trypanosoma cruzi populations isolated from different hosts and vectors is very important to clarify the epidemiology of Chagas disease. METHODS: An epidemiological study was conducted in a Brazilian endemic area for Chagas disease, including 76 chronic chagasic individuals (96.1% with an indeterminate form; 46.1% with positive hemoculture). RESULTS: T. cruzi I (TcI) was isolated from one child and TcII was found in the remaining (97.1%) subjects. Low-stringency single-specific-primer-polymerase chain reaction (LSSP-PCR) showed high heterogeneity among TcII populations (46% of shared bands); however, high similarities (80-100%) among pairs of mothers/children, siblings, or cousins were detected. CONCLUSIONS: LSSP-PCR showed potential for identifying similar parasite populations among individuals with close kinship in epidemiological studies of Chagas disease.

High similarity of Trypanosoma cruzi kDNA genetic profiles detected by LSSP-PCR within family groups in an endemic area of Chagas disease in Brazil

Introduction Determining the genetic similarities among Trypanosoma cruzi populations isolated from different hosts and vectors is very important to clarify the epidemiology of Chagas disease. Methods An epidemiological study was conducted in a Brazilian endemic area for Chagas disease, including 76 chronic chagasic individuals (96.1% with an indeterminate form; 46.1% with positive hemoculture). Results T. cruzi I (TcI) was isolated from one child and TcII was found in the remaining (97.1%) subjects. Low-stringency single-specific-primer-polymerase chain reaction (LSSP-PCR) showed high heterogeneity among TcII populations (46% of shared bands); however, high similarities (80-100%) among pairs of mothers/children, siblings, or cousins were detected. Conclusions LSSP-PCR showed potential for identifying similar parasite populations among individuals with close kinship in epidemiological studies of Chagas disease. .

Trypanosoma cruzi experimental congenital transmission associated with TcV and TcI subpatent maternal parasitemia.

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.