A Current Update on Neospora caninum

Abstract

Neospora caninum is an apicomplexan protozoan parasite, which was first identified as a cause of canine paralysis. This parasite is now recognized as an important cause of reproductive problems and abortion in cows. Prior to its first recognition in Norwegian dogs in 1984 and consequential classification as a distinct species in 1988, many N. caninum infections were misdiagnosed as toxoplasmosis. Neospora has a complex life cycle and transmission routes. Carnivores probably become infected by ingesting tissue cysts containing bradyzoites, and herbivores probably become infected by the ingestion of food or drinking water contaminated by N. caninum sporulated oocysts from the feces of carnivores. During pregnancy it becomes activated again, breaks out of the tissue cysts and migrates to the placenta. Infection of the placenta may lead to abortion, which would provide a source of contaminated meat for definitive hosts. In addition, the parasite may be transmitted to the foetus, which can lead to the birth of congenitally and persistently infected calves. Most reports of neosporosis outbreaks have occurred in cows that are intensively managed; thus, the incidence increases as larger cattle farms with intensive feeding practices become more common. Immunofluorescent antibody test (IFAT) and indirect enzyme-linked immunosorbent assay (ELISA) and histopathology of fetus are used for diagnosis. At present, there is no effective treatment for bovine neosporosis. Control of abortion in infected cattle depends on saving food and water sources and the grazing environment from feces of carnivores, properly discarding aborted feoutus and control of dog.