[Immunological studies in hamsters (Cricetus auratus) infected with Schistosoma mansoni]

Evaluation of the resistance to Schistosoma mansoni infection in Nectomys squamipes (Rodentia: Cricetidae), a natural host of infection in Brazil

The development of resistance in three stages throughout an active infection (pre-ovular, acute and initial chronic stages) was studied, comparing the total number of adult worms recovered from the reinfected group and the control groups. It was shown that Nectomys squamipes was unable to develop resistance in the tested conditions and, on the other hand, reinfection in the pre-ovular period of the parasite led the rodent to present the phenomenonacilitation, with reduction of natural resistance and an increase in the parasite load. These results suggest the existence of other forms of immunity diverse from the concomitant immunity in the host-parasite relationship, according to the employed model.

[Schistosoma mansoni: implantation of worms into the peritoneal cavity with a view to immunoprotection]

Tentou-se obter imunoproteção contra infecção cercariana pela inoculação de vermes vivos na cavidade peritoneal de camundongos. Embora os vermes sobrevivessem bem nestas condições e não ocorresse postura de ovos, não foi possível obter imunoproteção, Também a inoculação de ovos viáveis por via sangüínea e peritoneal não propiciou o aparecimento de imunoproteção nos camundongos com vermes na cavidade peritoneal.