Drug-resistant HIV increasing, UK study finds
Over a quarter of people newly infected with HIV in the UK and not yet receiving treatment may be carrying mutant virus strains already resistant to antiretroviral drugs, according to a study reported in the 5 May issue of the British Medical Journal.
The study, which was conducted by the UK collaborative group on monitoring the transmission of HIV drug resistance, used genetic tests to measure viral drug resistance within 18 months of infection in 69 subjects who contracted the virus between 1994 and 2000. The researchers detected primary resistance to antiviral drugs that is, in individuals not yet treated with drugs in 14% of cases over the seven-year period. Of the 26 patients tested last year, seven, or 27%, had a resistant virus. A calculation of the risk of primary infection with drug-resistant virus suggested a steady increase since 1994, reaching a risk of about one in five by last year.
Corresponding author of the study Dr Deenan Pillay, with the UKs Public Health Laboratory Service and Birmingham University Medical School, notes that the results are based on small numbers of patients and have therefore wide confidence intervals, so they should be taken as only indicative of what seems to be a disturbing trend. That trend, the researchers believe, is probably fuelled by the increasing use of antiretroviral drugs in the UK. Another contributing factor, they say, could be the growing number of people engaging in unprotected sex among groups at high risk of HIV infection, which increases the likelihood of being infected by someone who has already been treated with antiretroviral drugs.
Commenting on the UK findings to the Bulletin, virologist and HIV-resistance expert Professor Mark Wainberg, director of the McGill University AIDS Centre in Montreal, Canada, said: It is shocking. Its higher than anything Ive seen until now, and if its right, the UK would appear to be leading the world in regard to transmission of drug-resistant virus. Wainberg says that the figures are much greater than the 89% he reported from Canada last year. Reported figures from the US are between 15% and 20%.
If widespread access to treatment in the UK is a reason for high resistance rates, what are the implications for developing countries where the epidemic is most prevalent?
Dr Lynn Morris, head of the AIDS unit at South Africas National Institute for Virology in Johannesburg, has conducted genetic analysis of HIV in more than 70 recently infected drug-naïve patients. At this stage, she told the Bulletin, we havent found any resistant viruses.
Most patients in this part of the world, of course, still do not have access to antiretrovirals, so there is little pressure on the virus to mutate. But current efforts to lower the cost of these drugs and expand access to them in developing countries could increase the risk of resistance and its transmission. The threat of resistance definitely doesnt mean that we shouldnt give drugs to developing countries, says Morris. If we use that argument then we shouldnt be using TB drugs either. I think we need to make sure that people who get drugs are closely monitored and that theyre on the right therapies.
WHO, in collaboration with the International AIDS Society and Italys Istituto Superiore di Sanità, is planning a global HIV resistance monitoring network that, among other things, will keep track of trends in the prevalence of HIV drug resistance in parts of the world where antiretroviral therapy is being introduced.
Karen Birmingham, London, UK