Endogenous transplacental transmission of Neospora caninum during successive pregnancies across three generations of naturally infected sheep

In this study, involving three generations of ewes naturally infected byN. caninum, we demonstrated that endogenous transplacental transmission may also be highly efficient in the ovine host since transmission of infection occurred in 96.6% of gestations and the congenital infection rate ranged between 66.7 and 93%. Nevertheless, parasite burdens decreased gradually in consecutive generations. Reactivation of latent infections had a strong impact on the pregnancy outcome, with high mortality rates recorded in the offspring of the two first generations of ewes (21.4 –46.1%). Histological examination of the brain revealed that all aborted foetuses had characteristic lesions of neosporosis (necrotic glial foci) and a few parasite cysts, whereas most stillborn and newborn lambs that died shortly after birth had non-specific lesions (mild glial foci without necro sis) and parasite cysts were more frequent. Microsatellite analysis revealed scarce genetic variability in theN. caninum population, in accordance with a scenario in which infections were of a single origin and were exclusively maintained by clonal propagation through endogenous transplacental transmission.
Source: Veterinary Research - Category: Veterinary Research Source Type: research