812 Risk Factors for Kaposi's Sarcoma-associated Herpesvirus Infection among Homosexual Men at High Risk for HIV Infection in Brazil L. A. Lima*1,2, M. Schechter1, F. J. Jenkins3, P. S. Moore3,4, N. M. Renwick4, L. H. Harrison3 1Univ Federal do Rio de Janeiro, Brazil; 2Johns Hopkins Univ, Baltimore, MD; 3Univ of Pittsburgh, PA; and 4Columbia Univ, New York, NY
Background: Little is known about the epidemiology of Kaposi's Sarcoma-associated Herpesvirus (KSHV) infection among homosexual men in developing countries. We evaluated the KSHV epidemiology in a well-characterized cohort of homosexual men in Rio de Janeiro, Brazil.
Methods: A cross-sectional design was used to evaluate risk factors for KSHV infection among homosexual men participating in a HIV seroincidence cohort study. Stored blood samples were tested for the presence of KSHV antibodies using lytic BCBL-induced IFA and ELISA K8.1. KSHV infection was defined as positivity for both assays and risk factors were evaluated comparing cases of KSHV infection with persons who were negative on both assays. Discordant results were investigated: 1) by comparing the Lytic+ELISA- group to the Lytic-ELISA- group; 2) by performing a sensitivity analysis randomly allocating persons from the Lytic+ELISA- group to the Lytic+ELISA+ group, for different rates of false negativity for the ELISA, using the assumption that the lytic IFA was a perfect test. In the evaluation of discordant results, variables found associated with KSHV infection by comparing Lytic+ELISA+ to Lytic-ELISA- persons were used. Statistical analysis was done using Stata 5.0.
Results: Of 927 samples analyzed, 681 (73.5%) were positive by lytic IFA, 130 (14.0%) were positive for ELISA, and 125 (13.5%) and 207 (22.3%) were positive and negative, respectively, for both assays. Significant univariate associations with KSHV infection were age, age of first sex with men, household income, sex for money, sex after drugs, unprotected oral sex with casual partners, anal sex with lubricants, HIV infection, serologic evidence of previous syphilis, and hepatitis B infection. In the logistic regression analysis, age > 35 years (OR 2.7, 95% CI 1.3- 5.7), less than 8 years of education (OR 3.1, 95% CI 1.4- 6.8), sex at first encounter (OR 2.1, 95% CI 1.0- 4.1), anal sex with a stable partner (OR 1.9, 95% 0.9- 3.8), HIV infection (OR 5.3, 95% CI 2.1- 13.4), and hepatitis B infection (OR 2.5, 95% CI 1.3- 5.1) were associated with KSHV infection. When the Lytic+ELISA- and Lytic-ELISA- subjects were compared, the odds ratios tended to move toward the unity for most variables, including HIV and hepatitis B infection. The sensitivity analysis showed similar results.
Conclusions: KSHV infection among homosexual men in Brazil, similar to developed countries, appears to be transmitted sexually. Lytic BCBL 1-induced IFA is less specific than the K8.1 ELISA.