Taenia solium cysticercosis: immunity in pigs induced by primary infection

The present study demonstrates that pigs experimentally infected with Taeni a solium eggs develop resistance to reinfection that lasts at least five mo nths. Thirteen 2-month-old piglets were infected with eggs of Taenia solium . After 5 months, two pigs were euthanized and five were challenged with eg gs from a second tapeworm. Nine months after the first infection, six pigs were challenged with a third tapeworm. All II challenged pigs were euthaniz ed 2 months after reinfection. In order to confirm the infectivity of the e ggs, several piglets were inoculated with each taenia, Two of the five pigs reinfected after 5 months did not develop metacestodes, two showed few cas eous non-infective forms and in the fifth pie, 14% of the metacestodes were vesicular and 86% colloidal and caseous, In the six animals challenged 9 m onths after the first infection, three were heavily infected with vesicular metacestodes and the other three showed only colloid and caseous forms in muscles. All parasites found in brains were vesicular. We conclude that imm unity due to primary infection lasts at least 5 months. At 2 months of infe ction antigens of 24 and 39-42 kDa were the most frequently recognised, In those pigs with only a few caseous cysts in muscles and/or vesicular ones i n brains no antibodies were detected. (C) 1999 Elsevier Science B.V. All ri ghts reserved.