Vaccinal efficacy of Toxoplasma gondii S48 strain tested in an experimental trial in goats.

Toxoplasmosis due to Toxoplasma gondii represents the second cause of abort ion of dairy goats in France. A live vaccine (S48 strain, Ovilis Toxovax (R )) approved in sheep was tested in experimental conditions in goats. Goats were inoculated intramuscularly with vaccine 1 mont before mating. Two grou ps of vaccinated (n=17) and unvaccinated (n=16) goats were defined and chal lenged with 10,000 oocysts on day 90 of pregnancy. The evolution was quite different according to the initial level of ELISA antibody titers. In anima ls having very low low antibody titers, vaccination induced an increase of rectal temperature and of serological titers with large individual variatio ns. After challenge, a rise in rectal temperature was recorded only in unva ccinated animals whereas both vaccinated and unvaccinated goats showed a dr amatic increase in antibody titers. Percentages of abortion and stillbirth were respectively 0 and 25% in the vaccinated group and 25 and 12.5% in the unvaccinated one. In animals exhibiting higher initial antibody titers, re ctal temperature and serological responses to vaccination and challenge wer e less clear.