October 1, 2008
The AIDS pandemic in humans originated at least three decades earlier than previously thought, and it may have been triggered by rapid urbanization in west-central Africa during the early 20th century, according to an international team of researchers.
A better understanding of the conditions that helped fuel the pandemic could be key in controlling the disease and preventing future outbreaks of other emerging viruses.
"Rapid urbanization was the turning point that allowed the pandemic to start," said Michael Worobey, an evolutionary biologist at the University of Arizona, Tucson, and lead author of the study.
"We as human beings made some changes that took a virus that could not exist on its own and turned it into a successful epidemic," he added.
Birth of AIDS
Until now it was thought that HIV-1 Group M, the strain of HIV that causes the most infections worldwide, originated in 1930 in Cameroon.
Epidemic levels of AIDS and HIV-1 infections started appearing in Leopoldville, Belgian Congo (now Kinshasa, Democratic Republic of the Congo), around 1960.
Findings from the new study, however, suggest that the virus most likely started circulating among humans in sub-Saharan Africa sometime between 1884 and 1924.
Worobey and his colleagues made the discovery while analyzing tissue samples collected between 1958 and 1960 from Kinshasa. One of them, acquired in 1960, contained bits of HIV-1 RNA, the virus's genetic material.
The researchers compared the 1960 virus with the oldest known HIV-1 strain, which was obtained in 1959 and evolved independently of the 1960 variant. They found that the 1960 version was significantly different.
Next the researchers constructed an evolutionary family tree of the HIV-1 virus, made up of both the 1959 and 1960 strains along with more than a hundred modern viral sequences.
Using a mathematical model, Worobey and his colleagues discovered that the 1960 strain must have been evolving for at least 40 years to account for the number of differences from the 1959 strain.
The model also traced the most recent common ancestor of both strains to 1908.
The team's findings appear today in the journal Nature.
Lurking Danger
"This confirms that this was a virus that was lurking around for many decades before it exploded into the human population to become a noticeable pandemic, as opposed to something that started in the '70s or '80s," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), in Maryland.
NIAID funded the study along with the National Institutes of Health.
"It solidifies our understanding of the timetable of how this virus emerged from the chimpanzees to establish itself as a human infection," Fauci added.
"[HIV-1] flew below the radar level for decades until social conditions such as the end of colonization, migration of people to cities, increase in prostitution, and promiscuous sexual activity made it much easier for the disease to explode into a pandemic," Fauci explained.
More Mutations
Robert Garry is a microbiologist at New Orleans's Tulane University who was not involved with the study.
In the late 1980s, Garry was the first scientist to examine tissues samples taken from the U.S.'s first confirmed AIDS patient, who died in 1969.
"This study is very important, and what they are finding here is when the human virus started circulating in people," he said. "We still don't know when exactly the virus jumped from chimpanzees to humans, but it may be pushed back even further with this study.
"There will be other emerging viruses in the future, and what we learn about the conditions that help viruses spread, be it social changes or changes within the virus itself, will make us better prepared for other epidemics," he said.
Garry also argues that, though the rapid growth of cities in west-central Africa may have sparked the spread of infections, the virus itself underwent some sort of genetic change to facilitate transmission.
"We have to figure out what that change was," he cautioned.
Source:Amitabh Avasthi - National Geographic News
Showing posts with label pandemic. Show all posts
Showing posts with label pandemic. Show all posts
Monday, October 6, 2008
Saturday, September 27, 2008
World Faces Global Pandemic Of Antibiotic Resistance, Experts Warn
Sep. 18, 2008) — Vital components of modern medicine such as major surgery, organ transplantation, and cancer chemotherapy will be threatened if antibiotic resistance is not tackled urgently, warn experts on bmj.com.
A concerted global response is needed to address rising rates of bacterial resistance caused by the use and abuse of antibiotics or "we will return to the pre-antibiotic era", write Professor Otto Cars and colleagues in an editorial.
All antibiotic use "uses up" some of the effectiveness of that antibiotic, diminishing the ability to use it in the future, write the authors, and antibiotics can no longer be considered as a renewable source.
They point out that existing antibiotics are losing their effect at an alarming pace, while the development of new antibiotics is declining. More than a dozen new classes of antibiotics were developed between 1930 and 1970, but only two new classes have been developed since then.
According to the European Centre for Disease Prevention and Control, the most important disease threat in Europe is from micro-organisms that have become resistant to antibiotics. As far back as 2000, the World Health Organisation was calling for a massive effort to address the problem of antimicrobial resistance to prevent the "health catastrophe of tomorrow".
So why has so little been done to address the problem of resistance, ask the authors?
Antibiotics are over prescribed, still illegally sold over the counter in some EU countries, and self medication with leftover medicines is commonplace.
There are alarming reports about serious consequences of antibiotic resistance from all around the world. However, there is still a dearth of data on the magnitude and burden of antibiotic resistance, or its economic impact on individuals, health care, and society. This, they suggest, may explain why there has been little response to this public health threat from politicians, public health workers, and consumers.
In addition, there are significant scientific challenges but few incentives to developing new antibiotics, state the authors.
The authors believe that priority must be given to the most urgently needed antibiotics and incentives given for developing antibacterials with new mechanisms of action. In addition, "the use of new antibiotics must be safeguarded by regulations and practices that ensure rational use, to avoid repeating the mistakes we have made by overusing the old ones", they say.
They point out that reducing consumer demand could be the strongest force to driving change—individuals must be educated to understand that their choice to use an antibiotic will affect the possibility of effectively treating bacterial infections in other people.
But, they claim, the ultimate responsibility for coordination and resources rests with national governments, WHO and other international stakeholders.
Not only is there an urgent need for up-to-date information on the level of antibiotic resistance, but also for evidence of effective interventions for the prevention and control of antibiotic resistance at national and local levels, while more focus is needed on infectious diseases, they conclude.
--------------------------------------------------------------------------------
Adapted from materials provided by BMJ-British Medical Journal, via EurekAlert!, a service of AAAS.
Source: ScienceDaily
A concerted global response is needed to address rising rates of bacterial resistance caused by the use and abuse of antibiotics or "we will return to the pre-antibiotic era", write Professor Otto Cars and colleagues in an editorial.
All antibiotic use "uses up" some of the effectiveness of that antibiotic, diminishing the ability to use it in the future, write the authors, and antibiotics can no longer be considered as a renewable source.
They point out that existing antibiotics are losing their effect at an alarming pace, while the development of new antibiotics is declining. More than a dozen new classes of antibiotics were developed between 1930 and 1970, but only two new classes have been developed since then.
According to the European Centre for Disease Prevention and Control, the most important disease threat in Europe is from micro-organisms that have become resistant to antibiotics. As far back as 2000, the World Health Organisation was calling for a massive effort to address the problem of antimicrobial resistance to prevent the "health catastrophe of tomorrow".
So why has so little been done to address the problem of resistance, ask the authors?
Antibiotics are over prescribed, still illegally sold over the counter in some EU countries, and self medication with leftover medicines is commonplace.
There are alarming reports about serious consequences of antibiotic resistance from all around the world. However, there is still a dearth of data on the magnitude and burden of antibiotic resistance, or its economic impact on individuals, health care, and society. This, they suggest, may explain why there has been little response to this public health threat from politicians, public health workers, and consumers.
In addition, there are significant scientific challenges but few incentives to developing new antibiotics, state the authors.
The authors believe that priority must be given to the most urgently needed antibiotics and incentives given for developing antibacterials with new mechanisms of action. In addition, "the use of new antibiotics must be safeguarded by regulations and practices that ensure rational use, to avoid repeating the mistakes we have made by overusing the old ones", they say.
They point out that reducing consumer demand could be the strongest force to driving change—individuals must be educated to understand that their choice to use an antibiotic will affect the possibility of effectively treating bacterial infections in other people.
But, they claim, the ultimate responsibility for coordination and resources rests with national governments, WHO and other international stakeholders.
Not only is there an urgent need for up-to-date information on the level of antibiotic resistance, but also for evidence of effective interventions for the prevention and control of antibiotic resistance at national and local levels, while more focus is needed on infectious diseases, they conclude.
--------------------------------------------------------------------------------
Adapted from materials provided by BMJ-British Medical Journal, via EurekAlert!, a service of AAAS.
Source: ScienceDaily
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