Vertical transmission of Trypanosoma cruzi in Wistar rats during the acute phase of infection

Research on this form of transmission was carried out on female rats intradermally injected, before mating, with 1 x 10(4) metacyclic trypomastigotes of T. cruzi strains from dog (Pr) and human (YBM). The infected rats, as well as their offspring, were given parasitological, immunological and histopathological examinations during and after gestation. Healthy gestating rats were used as controls. Rats infected with T. cruzi strains showed clear signs of infection between 18 and 45 days post-inoculation (pi). Of 44 offspring from mothers infected with Pr, 4 males (9.1%) showed high parasitemia (432 and 240 tryps./mm3 of blood) at 30 and 40 days after birth, while direct blood examination, hemoculture and xenodiagnosis showed no infection in the other 40, or in the 52 offspring of rats infected with YBM. Anti-T. cruzi antibodies were found in appreciable quantities in infected mothers and in 44 out of 92 (47.8%) of the offspring, with titers that fluctuated between 1:32 and 1:2048 respectively. Histopathological studies of rats sacrificed at the end of gestation showed acute myocarditis and myositis of varying intensity and extent, characterized by abundant inflammatory infiltrate, in some cases associated with nests of amastigotes. The placentas showed moderate cellular infiltrate without parasites in the vascular stroma and amniotic fluid. The offspring of mothers infected with Chagas' disease were reinoculated and showed an acute phase characterized by low parasitemia (p < 0.05); after 60 days, the beginnings of chronic myocarditis and myositis could be observed, of a similar intensity to that observed in offspring born to infected mothers that were subsequently infected. These results confirm that T. cruzi can be transmitted vertically in Wistar rats; that a small number of offspring contract Chagasic infection congenitally; that anti-T. cruzi antibodies can pass from the mother and that these can modify the immune response in the offspring; that the pathogenicity of the strains of T. cruzi plays an important role in congenital transmission independently of origin or geographical location.