Serodiagnosis of Dermatophilus congolensis infection by counterimmunoelectrophoresis.

Sixty-one sera from animals that had contact with Dermatophilus congolensis were examined by comparing three serological methods; counterimmunoelectrophoresis, passive haemagglutination, and agar gel diffusion, and by using four different antigenic extracts of D congolensis. The counterimmunoelectrophoresis was the most satisfactory of the methods having been found to be specific and sensitive, easy to perform and suitable for screening large numbers of samples. It was also found to have a higher antibody detection rate (82.2 per cent) than the other methods thus making it suitable for seroepidemiological surveys. It was found to be capable of detecting multiple antibodies and also revealed dissimilarities among the different antigenic extracts. The cellular antigens of D congolensis were found to detect antibody in more sera than the extracellular antigen; the cell wall extract proved to be the most satisfactory of all, detecting antibody from the largest number of sera compared to the other extracts in all the three serological tests.