Transmissão transplacentária endógena de Neospora caninum em sucessivas gerações de cabras congenitamente infectadas

Abstract

Neospora caninum is an important etiological agent of reproductive disorders in ruminants around the world. Canids are the definitive hosts of the parasite and spread oocysts in the environment, that become infective and are the source of oral infection for other species, but the vertical transmission is the main source of N. caninum infection and its maintenance in livestock. Several seroprevalence studies using indirect fluorescent antibody test (IFAT) and enzyme-linked immunosorbent assay (ELISA) were performed in ruminants, but are still scarce in cattle and non-existent in goat studies that evaluate the transmission of N. caninum in successive generations. Therefore, the aim of this study was to evaluate the kinetics of antibodies anti-N. caninum by IFAT in up to five generations of dairy goats naturally infected by the parasite in order to know if all the animals are born infected or if it would be possible to be free of the infection over the generations. Serum for screening anti-N. caninum IgG was obtained from blood collected on the goat parturition and of the goat kids before the colostrum ingestion. Six goat families were evaluated, three families up to the fifth generation, two up to the fourth generation and one family up to the third generation. Transmission rates in more than one gestation of the same goat were also evaluated. One family up to the fourth generation was used as negative control. All goats were housed overnight and maintained in an isolated fenced paddock over the day, without contact with other animals. The results demonstrated that the infection by N. caninum was maintained throughout the generations of the studied families. The anti-N. caninum antibodies titers in the offspring were fluctuating (rising or declining) and had no influence on the parasite congenital transmission. Although only one to four pregnancies per goat were evaluated, the number of pregnancies did not influence the rate of congenital transmission, so it is suggested that the infection is maintained throughout the life of the goat and in several generations.