Intestinal parasitic infection and other sexually transmitted diseases in asymptomatic homosexual men.

76/133 (57%) asymptomatic homosexual men harboured intestinal parasites. Of these, 40 had Entamoeba histolytica or Giardia lamblia, or both. In a control group of heterosexual men, no pathogenic protozoa were found. Stool specimen cultures for Salmonella, Shigella, and Campylobacter were negative. 7% of the homosexual men were infected with Neisseria gonorrhoeae in the pharynx or rectum, or both, and 5% with Chlamydia trachomatis in the urethra or rectum. Serological evidence of syphilis was detected in 18 men (13.5%) of whom 2 were untreated. Serological markers of hepatitis A were found in 20% and of hepatitis B in 48%. The prevalence of antibodies to cytomegalovirus was higher in homosexual than in heterosexual men (88% versus 59%).