More African people acquiring HIV in the UK than previously thought

The number of African people who acquire their HIV infection in the UK (rather than in Africa) is greater than national surveillance data indicate, report researchers in the January 14th issue of AIDS. Based on a study in London, they suggest that between a quarter and a third of HIV-positive African people were infected in the United Kingdom. Moreover, among HIV-positive African men who have sex with men, almost half acquired their infection in the UK. The authors therefore argue that HIV prevention interventions for Africans must focus on reducing transmission within the UK as well as addressing infections acquired abroad.

It has generally been thought that the overwhelming majority of HIV-positive African people in the UK acquired their infection abroad. For example, the most recent Health Protection Agency report found that 88% of black African heterosexuals acquired their infection in Africa.

However Fiona Burns and colleagues from University College London wished to examine this issue further. As part of a study of newly diagnosed HIV infection among Africans in London, they asked 263 African adults who had been diagnosed with HIV for less than a year to complete a questionnaire that addressed risk behaviour before diagnosis. Medical notes were also consulted for information on symptoms, CD4 cell counts and other topics.

The researchers then analysed the data in order to decide where each individual was ‘definitely’, ‘probably’ or ‘likely to have been’ infected. For example, individuals who were symptomatic when they arrived in the UK or who had never had unprotected sexual intercourse in the UK would be considered ‘definitely infected abroad’. However, someone whose CD4 cell count dropped below 200 cells/mm³ within five years of being in the UK would only be judged ‘likely to have been infected abroad’.

Similarly, individuals who had had a negative HIV test result in the year before moving to the UK would be considered ‘probably infected in the UK’ and those who thought they may have had an HIV-positive partner in the UK (but not abroad) were judged ‘likely to have been infected in the UK’.

Three researchers made these assessments separately, and then compared their results. In some of the less clear-cut cases, there was disagreement between the researchers on the likely region of infection.

Overall, between 25% and 35% of the participants were thought to have acquired their HIV infection in the UK, and between 61% and 67% were thought to have been infected abroad (in each case, in Africa).

People from the following groups were more likely to have acquired their infection in the UK:

• Those who were aged 30 or under when they arrived in the UK.
• Those defining themselves as homosexual or bisexual (47% were thought to have been infected in the UK).
• Those with a higher CD4 count at diagnosis.

In relation to the differences between these findings and national surveillance data, Fiona Burns notes that the latter is primarily based on confidential reports by clinicians, who may prefer not to ask detailed questions about sexual behaviour at the time of diagnosis. Her study used a more detailed behavioural questionnaire some months after diagnosis, and she suggests that “the ability to draw upon richer sources of information in this study may account for the differences between our findings and those of the Health Protection Agency”.

Brian Rice of the Health Protection Agency (HPA) told aidsmap.com that it was also important to note some differences between the sample in Burns’ study and the population covered by the HPA. The study was carried out in London only, and was conducted among people born or raised in Africa, whereas the HPA’s data are national and do include people of African ethnicity who were born in the UK.

However he also confirmed that the HPA is refining its systems for recording probable country of infection. Moreover, their preliminary analyses do suggest that in London at least, the proportion of HIV acquired in the UK is indeed higher than previously reported.

Cross-border transmission

Meanwhile, Dutch researchers have found that one in ten heterosexual migrants who visit their country of origin report unprotected sex both there and in the Netherlands, which could facilitate the cross-border transmission of HIV.

They recruited 1938 heterosexual people of Caribbean or South American origin at a range of social venues in the Netherlands. Sixty per cent of the sample had travelled to their home country in the last five years, and they were asked about sexual behaviour both there and in the Netherlands.

Whilst four-fifths of the migrants who travelled were thought unlikely to be involved in cross-border HIV transmission, 9% were considered high risk, having had unprotected sex in both countries. Another 9% were judged to be moderate risk as they had sex in both countries, including unprotected sex with at least one casual partner.

Those in the high risk group tended to be male, older and to report more frequent trips to their homeland. The authors conclude that “older men who travel frequently are a risk group for cross-border transmission of STIs [sexually transmitted infections] and should be specifically approached for sexual health education to raise their risk awareness.”