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'1 in 10 reject antiretrovirals'
25/04/2006 13:50 - (SA)
Cape Town - One in 10 people who go onto antiretroviral medication will experience difficulties with the medication or their bodies will reject it completely.
This was heard in Cape Town on Tuesday at Microbicides 2006, the first international conference held in Africa into research into gels that could prevent HIV transmission in women.
Professor Mark Wainberg of the Aids Centre in Montreal, Canada, told the conference: "HIV can mutate at every possible basis, daily. Everyone has the capacity to resist antiretrovirals (medications to extend the lives of those with HIV). Ten percent of new patients have viruses that include at least one significant mutation associated with drug resistance."
As an example, he said that subtype C viruses of HIV - which predominate in southern Africa, India and China - "may have a low genetic barrier, with subtype B (which predominates in north America and Europe) it is almost impossible to develop resistance against Tenofivir (a new Aids wonder drug), but subtype C is more likely to develop a K65R mutation than B.
"To be useful a microbicide should be effective against all circulating HIV strains [of which there are 11]," Wainberg said.
Finding a vaccine
He said the problems bedevilling finding an effective vaccine were now challenging scientists working on microbicides. He postulated that HIV drug resistance could "develop because of microbicides. The virus will always do what is easiest for the virus".
Microbicides are hoped for Aids preventative methods that could prevent HIV in women who constitute two-thirds of those infected in the world.
Elof Johannsson of the Population Council expressed the exasperation of many when he said: "In 35 years of working in clinical trials I have never experienced such a difficult situation. We already have something that is effective to stop HIV, condoms, but men don't use them.
"If men used condoms we would not need microbicides."
Although there are seven phase three trials for microbicides - the final stage before a drug goes to market - not a single one of the managers of those trials expressed optimism at the efficacy of their products.
Trials
Johannsson said that with their phase three Carraguard trial which uses seaweed as the active ingredient, they were using the gel on almost 9 000 women in a time period stretching from March 2004 to March 2007.
The trials include women in the Western Cape. Limpopo and KwaZulu-Natal. Women presently have the highest HIV infection rates in KwaZulu-Natal at 43%, Johannsson said, while those in the Western Cape were the lowest at 18%, with 24% in Limpopo.
HIV-negative women aged between 16 to 40 take part in the trials.
He said that so far 200 of those women had become HIV positive. "We will have to rely on efficacy trials to tell us if the product works or not."
The conference has drawn delegates from across the world, with significant delegations from India, the country with the second-highest rate of infection after South Africa, Canada, Britain, the USA and elsewhere. It ends on Wednesday.
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