[Possibilities and limits of immunodiagnosis of strongyle infections in horses]

In an investigation period over 8 months the natural course of infection was studied by means of coproscopic and serological methods in 27 mares and 29 foals. The examination of the stool showed in mares, before the beginning of the grazing season, an infection rate of 100% with small and a rate of 7.4% with large strongyles (Str. vulgaris). Serologically the ELISA showed in foals only a distinct increase of antibody activity with the somatic antigen. The mares retained the high IgG-values of activity, which were already found at the beginning of the investigations. Even though the agglutination test can be applied for control of the effectiveness of therapy in a horse population, individual diagnostic possibilities remain limited. This is due to the reduced sensitivity and specificity of the IgG(T)-concentration under natural conditions of infection. The double-antibody-sandwich-ELISA technique has shown to be basically feasible as a test for antigens from small strongyles. Somatic antigen could most sensitively be demonstrated by antibodies to ES-antigen, ES-antigen, however, by antibodies against somatic antigens.