The Complement-fixation test in bilharziasis I. The value of different extracts of Schistosoma mansoni and Fasciola hepatica worms as antigens

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Abstract
1. Different extracts of adult worms of S. mansoni and F. hepatica have been examined in the C.F.T. for bilharziasis. Extracts of S. mansoni worms in Coca's solution, alcohol-ether and absolute alcohol after acetone extraction possess high antigenic activity, the first being the most specific but less sensitive than the others. Extracts in Coca's solution of alcohol-ether insoluble residues still showed slight activity while acetone and polysaccharide (formamide) extracts showed none.2. Using the Coca's extract of S. mansoni worms, the C.F.T. was positive in 83% of sera of untreated patients and 58% of treated. The figures using the alcohol-ether extract were 13 and 4% respectively and, for the alcoholic extract of acetone insoluble residue, 42 and 13%.3. Extracts of F. hepatica worms showed the same general trend, but even in the two extracts to show activity (alcohol-ether and alcohol extract of acetone insoluble material) the titre was too low for use in the test.4. Of rabbits immunized with three different fractions of S. mansoni worms only that given the Coca extract showed complement-fixing antibodies and then only with the homologous antigen. Skin tests on the rabbits were negative to each of the antigens used.5. The nature of the antigen in the C.F.T. is discussed, and it is suggested that the active portion is lipo-protein in nature or more than one substance is involved. For use in clinical diagnosis, an extract of S. mansoni worms in Coca's solution is recommended.Our grateful thanks are due to Mr O. D. Standen of the Wellcome Laboratories of Tropical Medicine, London, for his generous gift of worm powder, and to Professor G. Witenberg of the Hebrew University for his interest in our work.