DEVELOPMENT OF IMMUNITY TO SARCOCYSTOSIS IN DAIRY GOATS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 42  (5) , 800-804
Abstract
To determine the virulence of a microscopic Sarcocystis sp., forty-six 39-57 day old goats were inoculated with 101 to 106 sporocysts: 7 age-matched goats served as noninoculated controls. All 4 goats fed 106 sporocysts, all 4 goats fed 105 sporocysts, 2 of 4 goats fed 5 .times. 104 sporocysts, and 1 of 4 goats fed 104 sporocysts died of sarcocystosis, whereas 30 goats fed 101 to 103 sporocysts and the 7 noninoculated controls generally remained asymptomatic. In 3 immunization trials, groups of 7-9 goats were challenge exposed with 105 or 106 (2 or 20 median lethal dose) sporocysts at 14, 30 and 60 days after vaccination. In the 1st trial (14 days after vaccination), 2 of 2 goats vaccinated with 103 sporocysts and 1 of 2 goats vaccinated with 102 sporocysts survived a challenge exposure with 105 sporocysts, whereas 2 of 2 goats fed 101 sporocysts and the control goat died of acute sarcocystosis. In the 2nd trial (30 days after vaccination), 2 of 2 goats vaccinated with 103 sporocysts and the 2 goats vaccinated with 102 sporocysts survived a challenge exposure with 105 sporocysts, whereas 2 goats vaccinated with 101 sporocysts and the control goat died of acute sarcocystosis. In the 3rd trial (60 days after vaccination), 2 goats vaccinated with 5 .times. 104 sporocysts, 2 goats vaccinated with 103 sporocysts, and the 2 goats vaccinated with 102 sporocysts survived after challenge exposure with 106 sporocysts, whereas 2 goats vaccinated with 101 sporocysts and the control goat died of acute sarcocystosis. Goats vaccinated with 102 to 103 sporocysts develop protective immunity against lethal doses of Sarcocystis, whereas goats vaccinated with 101 sporocysts were not protected against a later infection with a lethal dose.

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