T. gondii is prevalent in most areas of the world and is of veterinary and
medical importance, because it may cause abortion or congenital disease in its
intermediate hosts. In sheep, T. gondii is an important cause of abortion, which can
result in considerable economic losses. Herbivores acquire infection mainly by the
ingestion of oocysts in water or contaminated food. Seroprevalence of T. gondii in
sheep have been reported extensively in different countries and the positive rates
ranged from 3% to 95%. The diagnosis of toxoplasmosis can be made by means of
indirect methods such as serological evaluation to detect specific antibodies. The
hypothesis that primary infection protects against reinfection is the basis for many
farmers not to discard sheep with a history of abortion. However, recent studies have
suggested that sheep persistently infected with T. gondii may transmit the infection
congenitally more frequently than expected. Ewes persistently infected with c
transmitted the infection congenitally, possibly due to an acute relapse process. This
result shows that the immunity acquired in the primary infection did not protect the
ewes against future T. gondii reinfections. The experimental T. gondii reinfection
triggered severe reproductive alterations (locomotive changes, malformations,
stillbirths and disability) in Santa Inês ewes primarily infected at different pregnancy
stages. Therefore, congenital T. gondii infection was common when ewes were
chronically infected prior to pregnancy, with or without reinfection during at various
stages of gestation.
Keywords: Congenital Toxoplasmosis, Ewes, Pregnancy, Toxoplasma gondii.
