Treatment Could Make HIV Epidemic Worse - Study
RTos 24.01.99 06:39
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By Maggie Fox, Health and Science Correspondent
ANAHEIM, Calif. (Reuters) - Wide use of drugs that suppress the
HIV virus that causes AIDS could end up making the epidemic even
worse, scientists warned.
Once the drugs are widely used in the community, people get
sloppy about taking them, which allows resistance to develop and
makes the virus even more likely to be passed on, said Sally
Blower of the University of California San Francisco.
Reporting to the annual meeting of the American Association for
the Advancement of Science (AAAS), she said Friday that even in
carefully controlled clinical trials some people did not take
their drugs as directed, giving the virus a chance to mutate into
drug-resistant forms.
"It could have beneficial effects, but it is also likely
that if treatment increases, the likelihood of drug resistance
increases," Blower said.
Blower and her colleagues used advanced mathematical models and
data from clinical drug trials, to show the course of the AIDS
epidemic.
When mathematicians take this rate and apply it to what is known
about how people take drugs in day-to-day life, Blower said the
picture is a grim one.
"If we increase treatment rates considerably and keep a
tight, tight rein on how (the drugs) are handed out, you would
have a beneficial effect on 15 percent of new infections,"
she said. In others words, 15 percent of new HIV infections, on
average over 10 years, would be prevented.
But if someone does not monitor patients very closely, Blower's
model predicts a 20 percent increase in new infections over 10
years.
Viruses and bacteria become resistant to drugs by mutating. Each
time an organism reproduces, a few mistakes creep into the
genetic code. Some of these will allow the microbe to evade a
drug's action.
The process is slow and if strong enough drugs are taken for a
long enough period of time the organisms will be killed before
this mutation develops.
But if a person takes a drug in a hit-or-miss way, or stops
taking it before all the bugs are killed, those that have a
tendency to resist the drugs will be the ones that survive and
multiply.
Eventually, the resistant bugs can be passed from person to
person -- something doctors have seen in hospitals around the
world with drug-resistant bacteria and are just starting to see
with HIV.
With HIV drugs this is very likely to happen, because the drugs
are difficult to take. They only work when used in a cocktail of
three, four or even five different compounds, each of which often
has to be taken several times a day and at different times of the
day.
Side-effects include nausea and diarrhea, which can discourage
regular use.
"There is going to be drug resistance and we've got to
expect that," Blower added, pointing out that
antibiotic-resistant forms of tuberculosis have existed since the
1950s.
Blower said the answer to the problem is not immediately
apparent.
"I'm not saying don't treat people," she said. "I
think people need to be treated. But we need to do it in a
careful manner."
Blower's group has made similar predictions with tuberculosis.
They said the World Health Organization strategy of training
health workers to watch people take their drugs -- known as
Directly Observed Treatment or DOTS -- will work well in
developed countries but may lead to more deaths in developing
countries because it does not work so well against drug-resistant
strains of TB.