Researchers call for new AIDS strategies

BARCELONA, Spain (CNN) -- Researchers Saturday urged doctors to adopt new strategies to slow the advance of drug resistance in AIDS patients, which makes treating the disease more difficult.

About 14,000 doctors, scientists and activists from around the world were expected to attend the 14th International AIDS Conference to discuss the epidemic, which has infected approximately 40 million people worldwide.

A study presented at the conference found that the percentage of newly diagnosed patients infected with drug-resistant forms of HIV is increasing. That increase limits the effectiveness of anti-AIDS drugs, the study concluded -- a trend that worries researchers.

"People are increasingly becoming infected with a virus that is difficult to treat," Dr. Frederick Hecht, of the University of California at San Francisco, reported.

The spread of a drug-resistant virus threatens treatment advances that have been credited in recent years with transforming AIDS/HIV from a fatal disease -- one where survival was measured in years -- to a chronic illness with survival potentially measured in decades.

New classes of drugs such as non-nucleoside reverse transcriptase inhibitors, or NNRTIs, have gotten much of the credit for that transformation. But Hecht said resistance to NNRTIs has increased from virtually none in 1996, when they were introduced, to 13 percent last year, and the trend seems to be continuing.

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The process is similar to what has happened with many antibiotics: In those cases, bacteria that are exposed to antibiotics mutate, becoming less vulnerable to medication and therefore harder to treat.

The same thing is happening with HIV. The UCSF researchers evaluated 225 patients over five years and found that resistance to NNRTIs rose. So, too, did resistance to the better-known class of drugs called protease inhibitors. The virus' resistance to protease inhibitors has more than doubled, from 3 percent to 7 percent, researchers found.

The increase in resistance is already affecting patient care. The authors said it took 12 weeks for drugs to show clinical effectiveness in drug-resistant patients, versus 4 weeks in others.

While the obvious strategy for combating resistance is to develop new, more effective drugs, such advances may take years. In the interim, Hecht called upon doctors to "integrate their strategies to decrease resistance."

That will require physician education to improve prescribing habits and instituting more effective prevention programs. In addition, Hecht said, HIV-positive patients too must shoulder much of the responsibility.

The effectiveness of the drugs has resulted in "a decrease in caution and increase in risky sexual behavior," he said. If the increase in drug resistance is to slow, such behavior will have to stop, he said.

Among other issues at the Barcelona conference, participants will hear about new compounds that attack the virus in a different way and will learn about the latest vaccine test results.

"There are three main messages that can emerge from the conference -- simplification of therapy, new families of compounds and therapeutic vaccines," Dr. Jose Gatell, a co-chair of the conference, told Reuters news agency.

The results on trials of new drugs -- fusion inhibitors and integrase inhibitors -- designed to prevent HIV from entering cells and to block virus replication, will also be discussed. Together these two types of drugs represent the biggest advance in AIDS treatment since the introduction of antiretroviral therapy, conference organizers say.

Prevention of AIDS is expected to be the second major focus of the week-long Barcelona conference.

AIDS has claimed 21.8 million lives, mostly in sub-Saharan Africa, where access to drugs is limited

With the rapid spread of AIDS in sub-Saharan Africa and emerging epidemics in China, India and eastern Europe, there is a wide consensus that more effective preventive measures are needed.

In a research report released ahead of the forthcoming conference, experts estimate that about 45 million more people worldwide will be infected with AIDS in the next years unless drastic action is taken.

Scientists say 29 million of these cases, or about two-thirds, can be prevented but that would cost $27 million between now and 2010.

To achieve that, annual worldwide spending on HIV prevention would have to be quadrupled from $1.2 billion to $4.8 billion by 2005, the U.N. AIDS agency, the World Health Organisation and other agencies' experts, who published the report, say.

Among other proposals, the authors of the Lancet report suggest that a package of the 12 most common prevention strategies is expanded.

Beside common prevention measures such as mass media campaigns, condom distribution or voluntary testing more attention should be paid to broader issues.

Training of local health careworkers, implementation of prevention programmes in rural areas and addressing wider social problems such as poverty have to be tackled, AIDS experts say.