Background: Genital herpes is usually caused by herpes simplex virus type 2 (HSV-2), with infections often being unrecognised by patients and/or clinicians. HSV-2 infections may be a risk factor for the transmission of human immunodeficiency virus (HIV) infection. Reliable tests for type-specific HSV antibodies are now readily available.
Objectives: To determine the seroprevalence of HSV-1 and -2 in HIV-seronegative gay men in a primary care setting in Melbourne, Australia, and to compare it with the rate in HIV-infected gay men. To assess the utility in a clinical setting of a type-specific HSV enzyme linked immunosorbent assay (ELISA) as compared with western blot.
Study design: We recruited a total of 300 HIV-seronegative homosexual men attending for HIV antibody testing, and HIV-infected men attending for CD4 lymphocyte count and viral load estimation. The subjects completed a questionnaire, and sera were sent for total IgG HSV testing and testing by Gull type-specific HSV ELISA assay. Selected serum samples were retested by western blotting and the results analysed.
Results: In total, 168 HIV-antibody negative men and 132 HIV-antibody positive men were recruited. Of all subjects, 73.3% had HSV-1 antibodies. This proportion did not differ between HIV-seronegative and seropositive men (P=0.48). About twenty percent of HIV-seronegative men and 61% of HIV-seropositive men had antibodies to HSV-2 (P<0.0001); 75.6% of HIV-seronegative men with antibodies to HSV-2 gave no history of genital herpes, as did 66.7% of HIV-seropositive men. Overall, in using the type-specific ELISA (Gull) assay, false negative, false positive or equivocal results were obtained in 33/300 (11%) of samples tested compared with western blot.
Conclusions: High rates of HSV-2 infection were found in homosexual males, with the rate for HIV-seropositive men being over twice that for HIV uninfected men. Most subjects were not aware of their infection with HSV-2. HIV-infected individuals were also older and had higher numbers of sexual partners, but we were unable to unambiguously establish that these variables contributed to the difference in HSV-2 seroprevalence rates. The Gull type-specific assay for HSV antibodies has significant problems with sensitivity and specificity at a discrepancy rate of 11%. Caution is advised in using this type-specific commercial assay for clinical purposes.