Impact of immigration and international travel on UK HIV and STI epidemics

Worldwide travel has increased in the past decade due, in part to its increasing accessibility and affordability. Affluent, highly travelled gay men were among the first to be affected by HIV back in the early 1980s. After the establishment of the HIV epidemic in the UK, most transmission occured within gay male communities in the UK. In recent years the epidemiology of HIV in the UK has been changing.

The number of heterosexually acquired infections diagnosed in the UK has risen steadily over the past 15 years, and in 1999 was, for the first time greater than the number of infections acquired through sex between men. The majority of HIV infections in heterosexuals in the UK occur in black Africans who have acquired their infection abroad.

The number of migrants to the UK including refugees and asylum seekers has increased in recent years. These migrants are predominantly young people aged less than 35 years and are likely to be a sexually active population.

Additionally, worldwide travel has increased in recent years, including both UK residents travelling abroad and nationals from other countries visiting the UK.

Recent studies have shown evidence of population-wide changes in sexual behaviour in the past decade, including the acquisition of new partners abroad. Taken together, these factors contribute to the increased probability of encountering STIs and HIV.

Researchers from the PHLS Communicable Disease Surveillance Centre analysed national surveillance data of newly diagnosed HIV infections and sentinel surveillance of both primary and secondary syphilis and antibiotic resistant gonorrhoea (the GRASP initiative) to assess the impact both immigration and worldwide travel are having on the UK's HIV, syphilis and gonorrhoea rates.

HIV

Between 2000 and 2001, following the introduction of new HIV diagnosis reporting by clinicians, country of infection was recorded for 84% of newly diagnosed HIV infections.

The UK was the likely country of infection for 28% (1042 of 3727) of those diagnosed, while for 47% (1755) it was an African country, 3% (105) Europe, and 3% (112) Asia.

Stark differences can be observed by exposure category; 85% (758 of 892) of HIV infections attributed to sex between men acquired in the UK, compared to 13% (284 of 2,243) of heterosexual infections. Between 2000 and 2001, 83% of heterosexuals diagnosed with HIV in the UK were born abroad. Of the heterosexuals born in the UK (358) 10% (37) were probably infected in Thailand, while 47% were infected in the UK.

For male heterosexuals born in the UK, where country of infection was known, 18% (35 of 196) were probably infected in Thailand compared to 30% in the UK.

Syphilis

The syphilis outbreak which occured in the UK in 2001 was largely confined to gay men. In London the majority of cases of syphilis in gay men were acquired in the UK (251 of 302). By comparison over half of all syphilis infections acquired heterosexually (50 of 95) were acquired abroad.

Gonorrhoea

Overall of the 2,260 cases collected in the GRASP clinics nationally during 2000, 13% report having had sex abroad in the last 3 months. Of the gay men reporting a sexual contact abroad 8% had sex in North America, and a further 8% in Central and South America. Of the heterosexual men , 13% of those with diagnosed gonorrhoea reported sex in the Far East in the previous 3 months.

The changing epidemiology of HIV and other STIs in the UK has been strongly influenced by migration and overseas travel and will continue to be so in the future.

Reference

McGarrigle C.The contribution of travel to diagnosed HIV and sexually transmitted infections in the United Kingdom.Abstract WePeC6167