Abstract
SUMMARY Absolute resistance to superinfection by Echinococcus granulosus in sheep was not stimulated within 9 months. Partial resistance, however, appeared to occur, particularly after a high initial dose. An overall decrease occurred in the serum albumin/globulin ratios in sheep with short-term infections of E. granulosus superimposed on chronic infections. With hydatid fluid as antigen, indirect haemagglutination titres of 1:400 or more indicated an infection of E. granulosus in sheep. Only a low level (1:200 or lower) of cross-reactivity was demonstrated by Taenia hydatigena, T. ovis, Multiceps multiceps and Linguatula serrata. Sheep that initially received large numbers of eggs (2000 to 100,000) showed titres of the order of 1:3200 at 9 months. After the challenge dose of eggs, the titres in these animals were not markedly changed. The superimposed infections in the animals fed 1000 eggs or fewer at the initial dose raised the titre 2- to 4-fold.
Published Version
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