Protective immunity to Sarcocystis capracanis-induced abortion in dairy goats.

Eleven female goats (Nos. 1 to 11) were each inoculated orally with 10(4) sporocysts of Sarcocystis capracanis, and four female goats (Nos. 12 to 15) were not inoculated. Between 31 and 69 days after inoculation (DAI) goats were mated with a single buck; one goat (No. 5) did not breed. Eight inoculated goats were challenged with 10(5) or 10(6) sporocysts, 135 DAI. Two of four goats challenged with 10(6) sporocysts and one of three goats challenged with 10(5) sporocysts aborted one month before the expected time of parturition. The three inoculated goats that were not challenged delivered healthy kids. All inoculated goats including the nonpregnant one (No. 5) were only mildly ill from the primary or challenge inoculations. Two of the four control goats challenged with 5 X 10(4) or 10(5) sporocysts aborted 21 days later, and both died of sarcocystosis 25 and 88 DAI. The two remaining control goats delivered normal kids. The results indicate that immunization prior to pregnancy protects some but not all goats from Sarcocystis-induced abortion.