Mapping Pathways is a multi-national project to develop and nurture a research-driven, community-led global understanding of the emerging evidence base around the adoption of antiretroviral-based prevention strategies to end the HIV/AIDS epidemic. The evidence base is more than results from clinical trials - it must include stakeholder and community perspectives as well.

20 March 2012

The Impact 'Treatment as Prevention' has on HIV Incidence in Africa

via, by gus Cairns

A longitudinal study from KwaZulu Natal province in South Africa is the first study from the global south to relate an increase in the proportion of adults on HIV treatment to a fall in HIV incidence, the 19th Conference on Retroviruses and Opportunistic Infections was told last week.

The study found evidence of a threshold effect; incidence started to fall once the proportion of all adults diagnosed with HIV in the area who were on treatment exceeded 30%.

Meanwhile, a study that took place in a week-long intensive health campaign in Uganda, as well as studies from areas as diverse as San Francisco and Swaziland, documented large increases in the proportion of people with HIV who are on treatment.

Falls in incidence in KwaZulu Natal

National surveys in South Africa have found evidence of significant falls in HIV incidence in recent years, but have related this to behavioural change rather than treatment. In the study presented at CROI, of a rural area of northern KwaZulu Natal centred on the mining town of Somkhele (Tanser), the researchers found a relationship between HIV treatment and a fall in infections.

They made use of a population-based HIV surveillance survey that has sampled 10,000 adults a year from 2004 onwards, by identifying 16,558 people who had taken at least two HIV tests during this period in order to gauge incidence rates. They then compared these data to individually linked data from the district-based HIV treatment and care programme.

Adult HIV prevalence in the area is high – 24%. The rate of new infections peaks at 8% a year in women in their early 20s and 5% a year in men in their late 20s. HIV testing rates are also high; researchers estimate that only 30% of the HIV-positive population is undiagnosed, a low proportion for Africa, and 75% of HIV-negative adults who have tested for HIV have done so more than once.

Since 2004, there has been a huge scale-up of HIV treatment, with 20,000 patients starting antiretroviral therapy since then, and by 2001 more than 40% of all adults diagnosed with HIV were on antiretroviral therapy (ART), and over 60% with a baseline CD4 count below 350 cells/mm3. HIV treatment at this CD4 threshold was only introduced in August 2011; previous to this it was 200 cells/mm3.

HIV incidence between 2004 and 2011 averaged 2.64% a year but was lower after 2009, when for the first time more than 30% of the diagnosed population was on ART. It was 3.0 to 3.5% 2007-09 but fell to 2.5% in 2010 and 2.0% in 2011.

After adjusting for HIV prevalence in the immediate area and demographic and behavioural variations, the researchers found that for every 10% increase in the proportion of adults on ART, the HIV incidence rate fell by 17%. Incidence was 40% lower when over 30% of the adult population was treated than when fewer than10% were. 

Read the Rest.

[Content that is linked from other sources is for informational purposes and should not construe a Mapping Pathways position.]

No comments:

Post a Comment