Enzyme immunoassays (EIAs) for the detection of anti-Haemophilus ducreyi serum IgA, IgG, and IgM antibodies.

Background And Objectives: Chancroid is a risk factor for heterosexually acquiring HIV. Controlling its spread may reduce HIV transmission.

Goal Of The Study: To develop EIAs for assessing antibody levels and for seroepidemiologic studies.

Study Design: Anti-Haemophilus ducreyi IgA, IgG and IgM EIAs were standardized using a crude cocktail antigen. Evaluation was on sera from Kenya, Rwanda, Thailand and The Gambia. The two-tailed student's t test was used to compare results.

Results: The specificity of IgA was 97% (95% confidence interval (CI): 95-99%), of IgG was 92% (95% CI: 89-95%), and of IgM was 99% (95% CI: 98-100%). The sensitivity of IgA was 88% (95% CI: 83-93%), of IgG was 93% (95% CI:89-97%), and of IgM was 78% (95% CI:71-85%) in patients having an ulceration for more than eight days. Thus, 95% (95% CI:92-98%) of the chancroid patients were seropositive for at least one antibody type. The IgG and IgA EIAs were more sensitive in patients older than 24 years of age. Higher IgG rates were found in HIV infected chancroid patients.

Conclusion: The EIAs should be useful for studying the kinetics of antibody levels and the epidemiology of H. ducreyi infection.