Less than 10% of HIV-positive individuals in South Africa will be eligible to receive antiretroviral therapy if World Health Organisation guidelines which mandate the use of anti-HIV therapy in patients with a CD4 cell count below 200 cells/mm3 are followed, according to a French-funded study published in the May 1st edition of the Journal of Acquired Immune Deficiency Syndromes.
The study also found that this would have only a limited impact on the spread of HIV. However, if US guidelines, which recommend HAART for individuals with a CD4 cell count below 350 cells/mm3 and a viral load above 55,000 copies/ml, are followed, over 50% of individuals would be eligible for treatment, and this would have the potential to reduce HIV transmission by over 70%.
In April 2002 investigators conducted a community-based cross-sectional study in a township near Johannesburg. Their study had three aims: to establish the proportion of the population requiring free HAART under WHO guidelines (a CD4 cell count below 200 cells/mm3); to assess the short-term impact of HAART on the spread of HIV; and to assess the impact of the US guidelines, which recommend the earlier initiation of HAART, on these estimates.
The study involved individuals aged between 15 and 49 years. Blood and urine samples were collected. The blood samples were tested for both HIV and syphilis. In addition, CD4 cell counts were measured for all individuals and HIV viral loads for individuals infected with HIV. Urine samples were tested for the presence of sexually transmitted infections. Individuals were also asked to complete a questionnaire about their sexual and partnership behaviour. In particular, individuals were asked if they had a spouse and how many nonspousal partners they had had in the past year.
A total of 930 individuals participated in the study, Of these, 21.8% were HIV-positive (17.4% of the men and 25.7% of the women). Prevalence was highest in men aged between 35-39 (34.4%), and women aged 25-29 (46.4%). HIV prevalence differed according to spousal status: 25.6% of those with a spouse were HIV-positive compared to 23.8% of individuals with nonspousal partners.
The prevalence of syphilis was 3.2% amongst men and 9.6% in women, and 6.2% of men and 6.9% of women had chlamydia.
Median HIV viral load was just under 56,000 copies/ml. However, the median viral load was 160,000 copies/ml in individuals with a CD4 cell count below 200 cells/mm3 and 46,800 copies/ml in individuals with a CD4 cell count above 200 cells/mm3.
The median CD4 cell count amongst HIV-positive individuals was 488 cells/mm3. A total of 9.5% of individuals had a CD4 cell count below 200 cells/mm3, and would be eligible for HAART under WHO guidelines. At the time of the study, 19% of individuals had a CD4 cell count between 200-350 cells/mm3, and if CD4 cell counts in these individuals fell by 50 cells/mm3, it was estimated that an additional 6.3% of individuals would need to start HAART, if WHO guidelines were followed, within two years.
In order to model the risk of HIV transmission, the researchers used the following assumptions and data:
- all people with HIV who received HAART would become less infectious
- all people who received HAART would have viral loads below 400 copies/ml on treatment
- the proportion of partnerships where the serostatus of the partner could be determined and the likelihood that that partner would be receiving HAART (the balance between spousal and non-spousal partnerships per year)
- the probability of transmission at a given level of viral load derived from a Ugandan study of transmission risk
If provision of HAART was restricted to individuals with a CD4 cell count below 200 cells/mm3, the investigators calculated that the annual risk of HIV transmission would be reduced by 11.9%.
The investigators then repeated their analysis using the treatment guidelines developed by the US Department of Health and Human Services. Using these guidelines, the investigators estimated that 56.3% of individuals would need to start HAART immediately, and that this would reduce the annual risk of HIV by 71.8%.
Commenting on their findings, the investigators stress that the provision of HAART using WHO guidelines would have only a limited impact on HIV transmission. They also caution that even if the more cautious US guidelines were used, HIV transmission was still likely to occur, as not all eligible individuals would access treatment, levels of adherence would be sub-optimal in some individuals, there is a high prevalence of STIs, and HIV transmission can still occur even if an individual has an undetectable viral load.
The investigators conclude, “the budget allocated for [HIV] prevention should not be in competition with the budget allocated for treatment and should not be reduced... the prevention of HIV should be based on established cost-effective prevention strategies such as condom distribution, blood and injection safety measures, treatment of STIs, and changes of sexual behaviour.”
Further information on this website
Delivering 3x5 HIV & AIDS Treatment In Practice #22
Infectiousness - factsheet
CD4 and viral load - booklet in the information for HIV-positive people series
Increases in unsafe sex temper HAART's effect on HIV transmission - news story
Belief that HAART makes HIV less serious linked with shift to unsafe sex in Dutch gay men - news story
Auvert B et al. Can highly active antiretroviral therapy reduce the spread of HIV: A study from a township in South Africa. JAIDS 36: 613-621, 2004.