Heterosexual transmission of HIV within UK still relatively rare: majority of cases of UK transmission involve gay men

HIV infections acquired through heterosexual intercourse within the United Kingdom represent less than 10% of all HIV infections amongst heterosexuals diagnosed in the UK, according to a paper published in the March 12^thon-line edition of the British Medical Journal. The authors, from the UK’s Health Protection Agency, emphasise that HIV transmission amongst gay men accounts for over 80% of HIV infections acquired in the UK. However, they acknowledge that even though small numbers of individuals are infected with HIV through heterosexual sex in the UK each year, the number is growing and is likely to continue to do so, particularly amongst ethnic minorities.

There is a common misunderstanding amongst the general public and in the media that the rapid increase in the heterosexual HIV epidemic in the UK is due to heterosexual transmission that takes place within the UK. Indeed, an editorial in the March 5^th edition of the BMJ, arguing that testing for HIV should no longer be afforded special status, incorrectly stated that heterosexual transmission of HIV has been the most common mode of transmission in the United Kingdom since 1991 and that HIV was rapidly spreading amongst heterosexuals in the UK.

Although there has been a substantial increase in heterosexual HIV in the UK, the majority of cases involve individuals who originated from, and were infected with HIV abroad, most notably Africa.

Data from the Health Protection Agency Centre for Infections provides an accurate picture of the extent of heterosexual transmission of HIV within the UK. Between 1985 – 2003 a total of 21,115 adult cases of HIV were reported in the UK. Of these only 1901 (9%) were probably infected in the UK.

Sexual contact with a partner from outside Europe accounted for almost two thirds of heterosexual infections acquired in the UK (62%, 1179 individuals), with 30% (569) involving a partner infected in Europe, including Europe, and for 8% (157) cases it was not possible to identify the country of the partner’s infection.

Of the 1179 individuals infected by a partner from outside Europe, 75% (882) were women, and of the 1006 for whom details were available, 44% (446) were white and 34% (341) were black. Over three-quarters (77%, 912 individuals) of their partners were probably infected in Africa, 16% (194) in Latin America and the Caribbean, and 6% (73) elsewhere.

Of the 569 individuals infected by partners who acquired HIV in Europe, 269 were women ,and of the 486 individuals with information available, 81% (393) were white. It is thought that 40% of(230) partners were probably infected in the UK.

Heterosexual transmission of HIV in the UK is, however, increasing from 144 in 1999 to 315 in 2003.

“Numbers of HIV infections acquired through heterosexual intercourse in the United Kingdom have risen in recent years but continue to represent a small proportion of all HIV infections diagnosed in heterosexuals”, write the investigators. They add, “homosexual men remain at greatest risk of acquiring HIV in the United Kingdom, accounting for an estimated 80% of newly acquired infections that were probably acquired in the United Kingdom.”

When heterosexual transmission did occur in the UK the investigators note that 62% of cases involved a sexual partner infected with HIV outside Europe.

However, the investigators conclude that there has been a steady increase in the small numbers of heterosexuals infected with HIV in the UK and “as the number of heterosexuals living with HIV (diagnosed and undiagnosed) in the United Kingdom grows, the likelihood of heterosexual transmission within the country will increase, particularly among ethnic minorities.”