HIV/AIDS spread most by those with moderate virus level
Pastor Dale Morgan
*HIV/AIDS spread most by those with moderate virus level*
22 Oct 2007 21:00:07 GMT
Source: Reuters
LONDON, Oct 22 (Reuters) - People with moderate levels of HIV/AIDS in
their blood are the most likely to infect others, researchers said on
Monday in a study that provides a better understanding of how the deadly
virus spreads.
Looking at several groups of HIV-positive people in Europe, the United
States and Africa, the researchers found that people with high levels of
the AIDS virus were the most infectious but had only limited time to
pass it on to others.
Those with moderate virus levels -- using a measure called viral load --
had plenty of virus circulating in their blood as well as the
opportunity to infect others, the researchers said.
This means that trying to halt the spread of AIDS by focusing on people
with the highest viral loads may not be the most effective approach,
said Christophe Fraser, an epidemiologist at Imperial College London who
led the study.
"The surprise was that those people with high viral loads actually
infected fewer people because they progressed to AIDS more quickly,"
Fraser said in a telephone interview.
The findings may also suggest that the virus has somehow adapted to find
the optimal balance between infectiousness and virulence in order to
maximise its chances of spreading -- something one would expect from
evolution, the researchers wrote in the Proceedings of the National
Academy of Sciences.
"We now want to see whether the virus has adapted in order to allow it
to infect the most people, which seems plausible given the results of
our study," Fraser said.
"While it is too early to sound the alarm, more research to prove or
disprove this theory is urgently needed."
More than 25 million people have died of AIDS since the incurable
disease that ravages the body's immune system was first recognized in
1981. Almost 40 million people now live with HIV, the virus that causes
AIDS, mostly in sub-Saharan Africa.
In their study, the researchers analysed previously published European
and African studies linking viral load, infectiousness and survival.
The researchers focused on people with medium viral loads as individuals
may show no symptoms and not progress to full-blown AIDS for about seven
to eight years. Those with high loads were typically people who
developed AIDS in a short period of time, usually two to three years,
Fraser said.
People with a medium viral load also form the largest, most common group
not to receive treatment, so these individuals are far more dangerous
when it comes to contributing to the AIDS epidemic, the researchers said.