ENTEBBE, 31 August 2010 (PlusNews) - A study of HIV-positive people in fishing communities on the shores of Lake Victoria in central Uganda has found that more than a quarter have "superinfections" that threaten both treatment and prevention efforts.

Superinfection occurs when an HIV-positive person is re-infected with another strain of HIV and can increase the likelihood of drug resistance to antiretroviral (ARV) therapy and speed up disease progression.

Now researchers in Uganda are looking for interventions aimed at educating HIV-positive members of the fishing communities around Lake Victoria about safe sex.

"We are starting to see transmission of viruses that are resistant to some drugs and need to inform even those already infected not to engage in risky behaviour to avoid superinfection," said Pontiano Kaleebu, head of the Basic Sciences Programme at the Uganda Virus Research Institute (MRC-UVRI), a unit of the Medical Research Council, which is conducting the three-year study.

Of the numerous sub-types of HIV circulating worldwide, A and D are the most common in Uganda and were found in most of the 117 men and women surveyed from five fishing communities in the two districts of Masaka and Wakiso. But the study also found that 29 percent had "recombinant" formS of HIV after being exposed to two different sub-types which then reform as new hybrid viruses. The presence of these recombinant strains - called A/D and D/A - is evidence that re-infection has occurred.

Kaleebu said there was a danger they could be re-infected with a strain of the virus that was resistant to certain ARVs, making treatment very difficult, but Juliet Mpondwe from the MRC said that data on the prevalence of drug-resistant HIV strains would only be available once the study was finished in 2012.

Speaking at a workshop in Entebbe, the main city in Wakiso District, the researchers said they wanted to develop interventions aimed at the fishing communities, such as education on how to reduce HIV risk through abstinence, being faithful to one partner, condom use and male medical circumcision.

They also planned to conduct further studies to better understand why HIV prevalence in these communities was so high - at 28 percent, four times the national average of 6.4 percent.

"We want to work with these communities and learn more in order to see how we can intervene, but also prepare for future research in vaccines and microbicides [female-controlled HIV prevention products]," said Kaleebu.

The spread of recombinant formS of HIV could have implications for vaccines and microbicides developed to guard against only certain sub-types.