- Between 2003 and 2005, 2,630 gay men learned they were HIV-positive, accounting for 23% of all HIV diagnoses; nearly half of them had been infected within the six months prior to diagnosis. - More than one in ten gay men "self-report" being HIV-positive. - Since 2000, an increase in risky sexual behaviors has been observed, particularly among HIV-positive men and those who are no longer certain they are still HIV-negative. - These risky sexual behaviors have led to an increase in sexually transmitted infections, notably syphilis and lymphogranuloma venereum. - In 2004, several cases of acute hepatitis C, linked to sexual practices involving blood, were reported among HIV-positive gay men. (R.A.)