Immunization for kidney worm disease (stephanuriasis) of swine I. Somatic antigens.

Nine somatic antigens derived from the excretory gland cells of adult Stephanurus dentatus were evaluated as vaccines for stephanuriasis of swine. Antigens were mixed v/v with Freund's complete adjuvant and administered intramuscularly or subcutaneously. Efficacy was evaluated by counting and comparing lesions and worms in the lymph nodes, livers, and kidney regions of principals and controls necropsied after oral challenge with infective S. dentatus larvae or after exposure to pastures naturally contaminated with such larvae. Against oral challenge, 6 vaccines produced statistically significant reductions in worm burdens of principals; 5 were significant at the 1% level and 1 at the 5% level. Two of these vaccines also reduced liver lesions significantly (P less than 0.05). Results of the natural challenge were inconclusive; small worm burdens were found in both principals and controls. None of the vaccines completely prevented migration to the liver or subsequent development and migration of a few worms to the kidney region. However, since worm burdens were reduced by as much as 92%, the vaccines could be useful in combating the disease, especially if combined with other control measures.