The annual conference of the UK's Public Health Laboratory Service has been presented with conflicting evidence about the transmission of drug resistant HIV in the UK, and new ethical questions about what to do with information about drug resistance in situations where drug resistant HIV could be transmitted to others.
Although evidence from London revealed at the conference suggests that transmission of drug resistant HIV is at much lower levels than some US and Australian studies public health predicted, epidemiological evidence was also presented which appears to confirm the transmission of drug resistant HIV between three sexually connected gay men.
A study conducted by South London Public Health Laboratory amongst patients attending HIV clinics at King's College Hospital and St Thomas's found only minimal evidence for the transmission of drug resistant HIV, amongst a cohort of 60 people from across the communities affected by HIV in south London.
Dr Mel Smith told the annual conference of the Public Health Laboratory Service that only seven percent of the cohort were found to have been infected with drug resistant virus between 1994-2000, much lower than the 14 percent that some American studies had reported.
The south London study also detected low levels of HIV resistance amongst treatment-experienced people, with 13 percent resistant to a nucleoside analogue, six percent to a protease inhibitor and a further six percent to a non-nucleoside analogue. Resistance was defined as genotypic resistance and a viral load above 2,000 copies/mL after failure of a regimen.
Public health officials will be taking some comfort from the apparently low levels of drug resistant infections reported in the study, the findings of which mirror a recent estimate that six percent of gay men in San Francisco had been infected with a strain of HIV resistant to at least one anti-HIV drug.
Dr Smith added a word of caution: "This is a relatively small study. A much larger investigation of 800 HIV-infected individuals is currently underway in south London which should give us a much firmer picture of the demographics of HIV infection in the area."
However, evidence which appears to confirm that drug resistant HIV can be easily transmitted when therapy is failing was presented by Dr Steve Taylor of the Communicable Diseases Surveillance Centre. Using blood samples and case histories taken from three gay men, who between 1994 and 2000 were in sequential relationships with one another, Dr Taylor demonstrated the transmission of a nucleoside resistant HIV strain from one man to his partner in 1994, who in turn passed the same mutation onto one of his sexual partners in 1998.
Whilst acknowledging the potential value of this information for HIV prevention campaigns, delegates expressed concern that the ability of epidemiologists to gather and attribute such detailed information to HIV-positive individuals might undermine the confidence of some patients in the confidentiality of their medical records. In particular, Dr Angus Nichol of the Communicable Disease Surveillance Centre drew attention the conviction under Scottish law of Craig Kelly for infecting his partner with HIV. The prosecution case relied upon the use of blood samples taken from Kelly during clinical trials, which were used in court as evidence to demonstrate that Kelly and his partner were infected with an identical strain of HIV.
Angus Nichol said he was concerned by how quickly the Scottish laboratory "rolled over and gave in" when faced with a subpoena for Kelly's clinical data. He added that, although English law did not currently allow for such a case concerning sexual transmission of HIV, should this situation change in the future and doctors were faced with a request from the authorities to obtain medical records provided in confidence, he hoped that clinicians would provide a “spirited resistance”.
The case reported by Dr Steve Taylor also raises questions. Will courts take the view in future that there is a greater duty of disclosure where individuals have drug resistant virus, and should clinicians make a particular point of counselling patients regarding the risks of transmission where drug resistance is detected?