Prevalence and incidence of pharyngeal gonorrhea in a longitudinal sample of men who have sex with men: the EXPLORE study.

BACKGROUND The prevalence of gonorrhea of the pharynx among select samples of men who have sex with men (MSM) ranges from 9% to 15%. To our knowledge, there have been no longitudinal studies in a prospective MSM cohort to estimate pharyngeal gonorrhea incidence or predictors of infection. We examined the prevalence, incidence, and sociodemographic and behavioral predictors of pharyngeal gonorrhea in a cohort of sexually active, human immunodeficiency virus-negative MSM. METHODS We conducted a prospective study of pharyngeal gonorrhea among MSM who were enrolled in a behavioral intervention study to prevent human immunodeficiency virus infection (Project EXPLORE). Participants were enrolled in this ancillary study from March 2001 through July 2003. At baseline and every 6 months thereafter until 31 July 2003, participants were tested for pharyngeal gonorrhea and were administered a questionnaire regarding their oral sex practices. Rectal and urethral gonorrhea testing were also performed. RESULTS Prevalence of pharyngeal gonorrhea was 5.5% (136 cases diagnosed from 2475 tests). The incidence rate was 11.2 cases per 100 person-years. Pharyngeal gonorrhea was positively associated with younger age and the number of insertive oral sex partners in the past 3 months. Ejaculation did not increase the risk of pharyngeal gonorrhea. Gonorrhea of the pharynx was asymptomatic in 92% of cases. CONCLUSIONS The pharynx is a common, asymptomatic reservoir for gonorrhea in sexually active MSM.