Risky sexual behaviour remains low after two years of ART in Uganda

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People receiving antiretroviral therapy in rural Uganda continue to have lower levels of risky sexual behaviour and a vastly reduced risk of HIV transmission after two years on treatment, US researchers from the Centers for Disease Control (CDC) reported on Tuesday at the 2006 Implementers meeting of the US President’s Emergency Plan for AIDS Relief in Durban, South Africa.

Earlier results of this study, published in January 2006, showed promising signs of a reduction in sexual risk-taking by people with HIV who were receiving antiretroviral therapy through a home-based care programme in the rural district of Tororo. That report contained data on six months of follow-up.

This week Rebecca Bunnell of CDC presented two years of follow-up on 454 individuals recruited between May 2003 and May 2004, one of the earliest groups to receive antiretroviral therapy in a rural area in Africa. All participants were treatment-naïve at baseline.


multivariate analysis

An extension of multivariable analysis that is used to model two or more outcomes at the same time.

risky behaviour

In HIV, refers to any behaviour or action that increases an individual’s probability of acquiring or transmitting HIV, such as having unprotected sex, having multiple partners or sharing drug injection equipment.


A serodiscordant couple is one in which one partner has HIV and the other has not. Many people dislike this word as it implies disagreement or conflict. Alternative terms include mixed status, magnetic or serodifferent.


The fluid portion of the blood.


The result of a statistical test which tells us whether the results of a study are likely to be due to chance and would not be confirmed if the study was repeated. All p-values are between 0 and 1; the most reliable studies have p-values very close to 0. A p-value of 0.001 means that there is a 1 in 1000 probability that the results are due to chance and do not reflect a real difference. A p-value of 0.05 means there is a 1 in 20 probability that the results are due to chance. When a p-value is 0.05 or below, the result is considered to be ‘statistically significant’. Confidence intervals give similar information to p-values but are easier to interpret. 

Participants were questioned at regular intervals on their sexual activity by counsellors who carried out home visits, delivering condoms and offering voluntary counselling and testing for partners. The home visits in themselves constitute an intervention, so the data presented by CDC cannot be generalised to all treatment programmes, since other programmes may carry out prevention activities differently.

Although sexual activity increased for both men and women, occasions of unprotected sexual intercourse showed a trend towards decline over the two years of follow-up. Unprotected sex with partners of negative or unknown HIV status declined dramatically, and only one sexual partner seroconverted during the follow-up period (year 1). Women had higher rates of unprotected sex than men, chiefly within marriage.

The research project also measured plasma viral load as a surrogate for infectivity, since plasma viral load has been shown to correlate closely with the risk of HIV transmission by an infected individual. The median viral load at baseline was 122,500 copies/ml (a level associated with a high risk of transmission). The median level at 24 months of follow-up was undetectable.

The researchers used viral load levels throughout the follow-up period together with the number of unprotected sexual acts with partners of unknown or negative HIV status to calculate the risk of HIV transmission. They estimated a 98% reduction in the risk of transmission had taken place throughout the follow-up period, and estimated that the rate of seroconversion per 1000 person years of follow-up had fallen from 45.7 to 1.0 over two years.

Rebecca Bunnell noted that partner testing has proved to be one of the most important prevention interventions in this study, since discordant partnerships in which both partners knew their HIV status had much higher levels of condom use. However, she said, “many couples did not believe they were discordant, even after testing, so we had to explain the concept of discordance to couples.”

Discussion after the presentation noted the particular need for prevention interventions of this sort for individuals on the waiting list for treatment, since they are likely to have much higher viral load levels, and so a much greater risk of transmission to partners.

Reduction in risky behaviour also seen in Kenya

A second study presented at the meeting showed similar trends in the Kenyan coastal city of Mombasa, and compared the risk behaviour of people receiving antiretroviral therapy and those receiving opportunistic infection prophylaxis.

The study, carried out by the Population Council Horizons project, recruited 322 HIV-positive people at four treatment sites (179 receiving ART, 143 receiving at least five months of isoniazid and/or cotrimoxazole prophylaxis).

Participants received safer sex counselling at the time of testing, and reminders of the need to avoid risk behaviours at the time of initiating treatment, and completed a semi-structured questionnaire after six months of follow-up.

Forty-five per cent of participants reported that they had been sexually active during the study period, 92% with a regular partner, 12% with a casual partner and 1% with a sex worker. Married participants were more likely to report sexual activity than single or widowed participants (69% vs 34% and 22% respectively, p

Individuals on ART were more likely to report sex with a regular partner than those on prophylaxis (97% vs 88%, p=0.046) and less likely to report sex with a casual partner (3% vs 23%).

Consistent condom use with regular partners occurred more frequently among those on ART (53% vs 22%), although it was not stated if this difference was statistically significant.

There were no significant differences in knowledge of a partner’s HIV status, or disclosure of HIV status to partners.

Multivariate analysis showed a fourfold greater risk of unprotected sex with regular partners among those not receiving ART (OR 4.3, p=0.000).

Presenting the study, Avina Sarna of the Population Council pointed out that a considerable risk of HIV transmission remained in both groups, and that more HIV prevention programmes are needed for HIV-positive people that emphasise disclosure of HIV status, partner testing and consistent condom use in regular partner relationships.


Bunnell R et al. Changes in sexual behaviour and risk of HIV transmission after two years of antiretroviral therapy and prevention interventions in rural Uganda. The 2006 HIV/AIDS Implementers Meeting of the President’s Emergency Plan for AIDS Relief, Durban, South Africa, abstract 87.

Luchters S, Sarna A, et al. Does being on HAART lower risky sexual behaviour? Insights from Mombasa, Kenya. The 2006 HIV/AIDS Implementers Meeting of the President’s Emergency Plan for AIDS Relief, Durban, South Africa, abstract 109.