Need for systematic HIV drug resistance testing


HIV is a tough enough diagnosis, but when one contracts a strain of HIV resistant to some life-prolonging medicines, treatment options are limited. A new study has found that transmitted HIV drug resistance may be on the rise in Africa, and the authors warn that unless resistance surveillance is increased, the continent's treatment programmes could suffer.

The study, led by the International Aids Vaccine Institute (IAVI) in five African countries, found that the prevalence of transmitted drug resistance in Rwanda, Uganda and Zambia was considerably higher than previously reported.

Of 408 people studied in Kenya, Rwanda, South Africa, Uganda and Zambia, 19 had transmitted resistance mutations. Resistance prevalence rose considerably during the study in Zambia and remained high throughout the study in Entebbe (Uganda).

"The message to take away from this study is the urgent need for regular drug resistance surveillance, which we currently do not have," said Omu Anzala, head of the Kenya AIDS Vaccine Institute. "If we can see transmitted resistance in such a small study then there could be much more going around."

"We saw what has happened with malaria over the years, with resistance developing against several drugs. We need to move quickly to ensure governments are aware and are implementing drug resistance surveillance to prevent the same thing happening with ARVs," he added.

In 2009 Kenya launched a five-year national plan on HIV drug resistance, prevention, monitoring and surveillance.

A separate study  in 2010 by PharmAccess African Studies to Evaluate Resistance (PASER), a project of the PharmAccess Foundation, a Dutch health NGO, found that nearly 6 percent of patients about to start HIV treatment for the first time already had resistance to standard first-line ART.

Speaking at a workshop on HIV drug resistance in Uganda in December 2010, Christine Watera, coordinator of Uganda's National HIV Drug Resistance Working Group, stressed the need for more research to map the prevalence of HIV drug resistance on a nationwide scale.

Setting up strategies

The UN World Health Organisation recommends that countries put in place strategies to assess and prevent drug resistance, including conducting surveys and developing early warning mechanisms based on indicators such as drug stock-outs and patients' adherence records.

"One of the major implications of transmitted drug resistance is that oftentimes the second choice drug regimen is more limited in some of these countries - for example, there may be issues with the cold chain... making treatment more challenging," said IAVI's Matt Price, lead author of the study.

"Governments should provide the appropriate support and ensure patients have adequate follow-up so if treatment begins to fail they can be put on new regimens," he added. "Early detection of patient failure is crucial, as is regular counselling and risk reduction behaviour."

Price noted that theoretically, the study findings could have an impact on treatment as prevention, which UNAIDS is promoting under its new 'Treatment 2.0' strategy.

"If I am taking PrEP [pre-exposure prophylaxis] and become exposed to a strain of HIV that is resistant to the drug I am taking, I could stand a better chance of becoming infected than if I were exposed to a non-resistant strain," he said. "But more research is required in this area... So far we do not know very much about resistance in treatment as prevention." - (PlusNews, February 2011)

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