Population viral load decreases in 'test and treat' study in Uganda

Positive changes in population-level HIV viral load distribution have been found one year after the implementation of key components of an HIV 'test-and-treat' strategy in rural Uganda. Population levels of viral load were lower, a higher proportion of people had an undetectable viral load (less than 50 copies/ml) and fewer individuals had a viral load greater than 100,000 copies/ml, according to a study presented by Dr Vivek Jain at the 19th International AIDS Conference (AIDS 2012) in Washington DC.

“The assessment of population-level HIV viral load is an important part of evaluating real-world effectiveness of test-and-treat strategies. Viral load suppression reflects effectiveness of the entire cascade of care from HIV diagnosis to linkage to treatment to suppression. Viral load distribution of a population can also provide insight into transmission,” said Dr Jain.

The findings are in contrast to a report of a field study among people receiving HIV care through the AIDS Support Organisation (TASO) in Uganda, which found no decreased risk of HIV acquisition among the HIV-negative partners of people receiving antireretroviral treatment through the programme.

Two community-wide health campaigns to diagnose HIV and link people to care were conducted in the Kakyerere Parish in May 2011 and May 2012 as part of a test-and-treat campaign. The health campaigns included awareness-raising of the importance of testing and a five-day HIV testing campaign, where fingerprick-based viral load testing was conducted using the Abbott HIV-1 RT-PCR test.

In total, 4343 individuals (2282 adults, 74% of the adult population in Kakyerere Parish) were screened in the first community health campaign in 2011, which increased to 4872 (2271 adults, 72% of the adult population) at the 2012 community health campaign.

7.8% (n=179 of 2282) of the adults were found to be HIV-positive in the 2011 campaign compared to a HIV prevalence of 9.4% (n=210 of 2271) in the 2012 campaign. This correlated with the average HIV prevalence of 8% in rural southwestern Uganda.

There was a significant increase in the percentage of HIV-infected patients who had an undetectable viral load year on year, from 37% (95%CI 30-45%) in the 2011 campaign, compared to 55% (95%CI 48-62%) in 20012. The proportion of people with a viral load greater than 100,000 copies/ml also decreased from 13% in 2011 to 3% in 2012. This is an important finding, according to the researchers, as this is the group most likely to transmit HIV due to higher viral loads. The median viral load also decreased between 2011 and 2012 from 2185 copies/ml (IQR:<486-33045) to less than 486 copies/ml (IQR: <486-7903).

In total, 46% of those diagnosed HIV-infected in 2011 were unaware of their status prior to the campaign. In 2011, 35% of the participants were male, compared to 45% in 2012. The median age of participants in 2011 was 19 (IQR: 9-38) and 20 (IQR: 9-38).

The community-based approach of this study creates a direct population measurement of viral load. When viral load is taken only from data at health facilities, it misses those people who are unaware of their status. However, the researchers warned that although there was a very representative sample and high coverage in the community, there is the possibility that different individuals took part in the testing campaign each year, which could skew results. The identification and assessment of viral loads in individuals who did not participate in the campaign is needed.

Nonetheless, this study moves towards true population estimates of community viral load in resource-limited settings where viral load testing is not part of routine clinical care, and shows the extent to which expansion of treatment can quickly reduce the proportion of infectious individuals in the population, as well as benefiting the people who are able to start treatment.