TRYPANOSOMA-CRUZI INFECTION IN THE OPOSSUM DIDELPHIS-MARSUPIALIS - ABSENCE OF NEONATAL TRANSMISSION AND PROTECTION BY MATERNAL ANTIBODIES IN EXPERIMENTAL INFECTIONS

The high rate of natural Trypanosoma cruzi infection found in opossums does not always correlate with appreciable densities of local triatom id populations. One alternative method which might bypass the inverteb rate vector is direct transmission from mother to offspring. This poss ibility was investigated in five T. cruzi infected females and their l itters (24 young). The influence of maternal antibodies transferred vi a lactation, on the course of experimental infection, was also examine d. Our results show that neonatal transmission is probably not respons ible for the high rate of natural T. cruzi infection among opossums. I n addition antibodies of maternal origin confer a partial Protection t o the young. This was demonstrated by the finding of a double prepaten cy period and 4,5 fold lower levels of circulating parasites, in exper imentally infected pouch young from infected as compared to control un infected mothes. On the other hand, the duration of patent Parasitemia was twice as long as that observed in the control group.