Preliminary investigation into the usefulness of the indirect haemagglutination

Summary To give an impression of the usefulness of indirect haemagglutination (IHA) in the diagnosis of lungworm infections in cattle under practical conditions, five calves vaccinated against Dictyocaulus viviparus and five unvaccinated calves were periodically subjected to clinical, parasitological, and serological examinations over a period of seven months. All calves grazed on a lungworm-infected plot. 82% of the observations in unvaccinated calves, which were positive with respect to one or more of the used parameters, concerned IHA-positive animals which, however, showed negative results with the parasitic parameters. The titre variation of the serological examination was a further indication of the fact that the IHA detected antibodies against lungworm antigens. No indications of false positive reactions were obtained. An investigation carried out on 46 farms on the correlation between serological and clinical findings on lungworm infections revealed a positive correlation in 80% of the groups between results obtained with both methods. The authors consider that IHA offers good prospects for the diagnosis of lung-worm infections.