Original article Trends in undiagnosed HIV-1 infection among attenders at genitourinary medicine clinics, England, Wales, and Northern Ireland: 1990-6

In 1996, the seroprevalence of undiagnosed HIV-1 infection was 5% in homosexualmen, 0.48% in heterosexual men, and 0.33% in heterosexual women. Between 1990 and 1996,there was a significant linear decrease in the seroprevalence of undiagnosed HIV-1 infectionamong homosexual and bisexual men within and outside London (p<0.0001; p=0.0141), equiv-alent to yearly decreases of 7.65% and 10.73% respectively. However, seroprevalence amonghomosexual and bisexual men under 25 years of age did not decline either inside or outside Lon-don.Seroprevalence among heterosexual men declined outside London (p<0.005),equivalent toan average annual decrease of 14.54%. There was a significant increase among male heterosexu-als inside London (p<0.05) equivalent to a 8.09% increase per annum.Seroprevalence over timewas unchanging among female heterosexuals both inside and outside London. Seroprevalencewas significantly higher among those who injected drugs than those who did not report injectingin the following groups: homosexual and bisexual males within London (p<0.005), male hetero-sexuals both within and outside London (p<0.05;p<0.05) and female heterosexuals within Lon-don (p<0.05).