Protecting babies: vaccine strategies to prevent foetopathy in Neospora caninum-infected cattle.

Neospora caninum is an apicomplexan protozoan parasite that is a significant infectious abortifacient agent in cattle. Despite the fact that it is a member of a well described taxonomic group, it is a relatively newly discovered parasite and its biology is not yet fully understood. Cattle become infected either congenitally via transplacental transmission or post-natally by ingesting oocysts derived from the definitive host; dogs and coyotes are the only definitive hosts that have been described to date. It is not known which of these two forms of transmission occurs most frequently and which is the most likely to result in abortion; there are no drugs available to treat infected cattle, so current control strategies rely on prevention of infection by management methods and strict hygiene; an effective vaccine would be a great advantage in its control. Neospora caninum is an economically important veterinary pathogen, but we can also draw analogies between its foetopathic effects and those of human pathogens such as Toxoplasma gondii, Chlamydophila abortus and Plasmodium falciparum. Understanding the immune response and the materno-foetal relationship in N. caninum-infected cattle may help us to design vaccination strategies, not only for neosporosis but also for other foetopathic agents.