— IN cash-starved regions of the world, deciding who should get anti-retroviral drugs for HIV is a tough call. Now it seems that one of the main tools for making that decision may be less reliable than it appeared.
World Health Organization guidelines recommend starting anti-retroviral drugs when someone's CD4 cell count has fallen below 350 cells per microlitre, an indicator of HIV infection, or for people with symptoms of AIDS whose CD4 count has dropped to below 200.
Brian Williams of the WHO and his colleagues studied HIV-positive and HIV-negative populations in eight African countries including Ethiopia, South Africa, Uganda and Zambia. They found that between 3 and 5 per cent of HIV-negative people had CD4 counts below 350.
What's more, when people with low pre-infection cell counts did contract HIV, and received anti-retrovirals, they survived for about nine years - the same as people with high counts (Journal of Infectious Diseases, vol 194, p 1450).
The new findings call into question just how much we understand about CD4 cells and their interaction with HIV, says Williams. "Generally, if you have high CD4 counts you can be considered to be doing pretty well and if you have very low counts, you're in trouble," says Williams.
But CD4 counts can vary a lot naturally so if you follow the WHO guidelines to the letter, then some people started on anti-retrovirals would not even be infected with HIV, he concludes.>