Sexual health
HIV & chlamydia diagnoses increasing
New HIV diagnoses by selected routes of infection, in the UK
New diagnoses of HIV among heterosexuals tripled between 1998 and 2003, reaching 3,800. Since 1999 heterosexual transmission has predominated. Before this, sex between men was the main route of infection in the UK. New diagnoses of HIV following sex between men exceeded 1,700 in 1991, after which the number fell to less than 1,400 in 1999. The annual figure then increased, exceeding 1,700 once more by 2001.
The number of diagnosed HIV-infected patients receiving care in the UK in 2003 exceeded 37,000. Half lived in Greater London.
An estimated 14,300 infected adults aged over 15 were undiagnosed. Among those infected through heterosexual activity, 39 per cent of men were estimated to be undiagnosed compared with 22 per cent of women.
New episodes of selected sexually transmitted infections, UK, 2000-2004
Chlamydia is the most common sexually transmitted infection (STI) in the UK. It is often undiagnosed, since it is asymptomatic in 70 per cent of infected women and 50 per cent of infected men.
Between 2000 and 2004, the rate of new diagnoses of chlamydia among people who attended Genitourinary Medicine (GUM) clinics greatly increased from 116 to 175 per 100,000.
The largest increases in chlamydia rates were seen in persons under the age of 16. However, the highest rates were in females aged 16 to 19 (1,339 per 100,000), and males aged 20 to 24 (1,034 per 100,000).
In 1999-2001 more men (15 per cent) had concurrent partners than did women (9 per cent). Concurrent sexual relationships increase the probability of STI transmission.
Sources: Health Protection Agency
Notes: Round figures are quoted for HIV diagnoses because these counts are subject to change as further reports are received.
Human immunodeficiency virus (HIV) is mainly transmitted through sex. Other routes of infection affect a much smaller group of people: for example injecting drug users and mother to infant.