 |
|
Preventing a pandemic: Study suggests strategies for containing a flu outbreak
August 04, 2005Containment in a medium-sized Southeast Asian community may be possible, though challenging, if implemented early, researchers say
Though quick to caution about the many things that could go wrong, researchers say that it may be possible to contain a Southeast Asian outbreak of avian influenza in humans, buying precious time for the production of a vaccine.
Using a computer model to simulate an outbreak in a rural Southeast Asian population, the scientists have shown how a combination of strategies, including targeted administration of antivirals, quarantine and prevaccination - even with a poorly effective vaccine - could potentially contain an outbreak in Southeast Asia under many circumstances.
The study, by Ira Longini of Emory University and colleagues, will be published online by the journal Science, at the Science Express website, on Thursday, 4 August.
"Our findings indicate that we have reason to be somewhat hopeful. If - or, more likely, when - an outbreak occurs in humans, there is a chance of containing it and preventing a pandemic. However, it will require a serious effort, with major planning and coordination, and there is no guarantee of success," said coauthor Elizabeth Halloran of Emory University.
"Early intervention could at least slow the pandemic, helping to reduce morbidity until a well-matched vaccine could be produced," she said.
The danger of avian flu is that the virus could develop into a new strain that could be transmitted among humans. The virus might mutate, or it might jump over to a human already infected with the flu and then mix, or "reassort," with the human flu virus. Because humans would have little or no immune protection against this strain, it could potentially cause a massive pandemic.
"There were three influenza pandemics in the 20th century alone. The threat of another pandemic, related to avian influenza, is real and very serious. Fortunately, as the new study shows, for the first time in human history, we have a chance of stopping the spread of a new influenza strain at the source through good surveillance and aggressive use of public health measures," said Katrina Kelner, Deputy Editor, Life Sciences, at Science.
A rural Southeast Asian population is a likely place for the new strain to emerge, so Longini and his colleagues based their model on the Thai 2000 census and a previous study of the social networks in the Nang Rong District in rural Thailand.
With this information, they simulated a population of 500,000 in which individuals mixed in a variety of settings, including households, household clusters, preschool groups, schools, workplaces, and a hospital. Social settings for casual contacts, such as might take place in markets, shops, and temples, were also included.
Using the model, the researchers analyzed how the disease, starting with a single case, would spread through the population in a variety of different scenarios.
They found that targeted use of antiviral drugs could be effective for containment as long as the intervention occurred within 21 days and the virus' reproductive number (which represents the average number of people within a population someone with the disease is able to infect) had a relatively moderate value of roughly 1.6.
A process of administering antiviral drugs to the people in the same mixing groups as the infected person, called TAP for "targeted antiviral prophylaxis," could contain the outbreak as long as it reached 80 percent of the people targeted. A related strategy, GTAP, for "geographically targeted antiviral prophylaxis," which targets people within a certain geographic range of the initial case, produced similar results as long as it achieved coverage of 90 percent.
Vaccination before the outbreak, even with a vaccine that is poorly matched to the actual virus strain, increased the effectiveness of TAP and GTAP.
For even higher viral reproductive numbers, household quarantines would also be necessary to contain the virus. A combination of TAP, prevaccination and quarantine could contain strains with a reproductive number around 2.4. A value of 2.4 is relatively contagious, though some other viruses such as measles are substantially higher. In all cases, early intervention would be essential.
The authors note in their study that the current World Health Organization stockpile of antivirals for avian flu could probably be sufficient to help contain a pandemic in a population like the one in the model, if the stockpile were deployed within two to three weeks of detection.
As part of their study, the researchers consulted with Thai ministry of health officials and concluded that public health workers may decide that TAP, rather than GTAP, is the more realistic strategy, given their resources.
This research effort is part of a network called MIDAS (Models for Infectious Disease Agents Study), supported by the National Institute of General Medical Sciences. A related paper from another group of MIDAS researchers is being published simultaneously in the journal Nature.
American Association for the Advancement of Scienc
The study, by Ira Longini of Emory University and colleagues, will be published online by the journal Science, at the Science Express website, on Thursday, 4 August.
"Our findings indicate that we have reason to be somewhat hopeful. If - or, more likely, when - an outbreak occurs in humans, there is a chance of containing it and preventing a pandemic. However, it will require a serious effort, with major planning and coordination, and there is no guarantee of success," said coauthor Elizabeth Halloran of Emory University.
"Early intervention could at least slow the pandemic, helping to reduce morbidity until a well-matched vaccine could be produced," she said.
The danger of avian flu is that the virus could develop into a new strain that could be transmitted among humans. The virus might mutate, or it might jump over to a human already infected with the flu and then mix, or "reassort," with the human flu virus. Because humans would have little or no immune protection against this strain, it could potentially cause a massive pandemic.
"There were three influenza pandemics in the 20th century alone. The threat of another pandemic, related to avian influenza, is real and very serious. Fortunately, as the new study shows, for the first time in human history, we have a chance of stopping the spread of a new influenza strain at the source through good surveillance and aggressive use of public health measures," said Katrina Kelner, Deputy Editor, Life Sciences, at Science.
A rural Southeast Asian population is a likely place for the new strain to emerge, so Longini and his colleagues based their model on the Thai 2000 census and a previous study of the social networks in the Nang Rong District in rural Thailand.
With this information, they simulated a population of 500,000 in which individuals mixed in a variety of settings, including households, household clusters, preschool groups, schools, workplaces, and a hospital. Social settings for casual contacts, such as might take place in markets, shops, and temples, were also included.
Using the model, the researchers analyzed how the disease, starting with a single case, would spread through the population in a variety of different scenarios.
They found that targeted use of antiviral drugs could be effective for containment as long as the intervention occurred within 21 days and the virus' reproductive number (which represents the average number of people within a population someone with the disease is able to infect) had a relatively moderate value of roughly 1.6.
A process of administering antiviral drugs to the people in the same mixing groups as the infected person, called TAP for "targeted antiviral prophylaxis," could contain the outbreak as long as it reached 80 percent of the people targeted. A related strategy, GTAP, for "geographically targeted antiviral prophylaxis," which targets people within a certain geographic range of the initial case, produced similar results as long as it achieved coverage of 90 percent.
Vaccination before the outbreak, even with a vaccine that is poorly matched to the actual virus strain, increased the effectiveness of TAP and GTAP.
For even higher viral reproductive numbers, household quarantines would also be necessary to contain the virus. A combination of TAP, prevaccination and quarantine could contain strains with a reproductive number around 2.4. A value of 2.4 is relatively contagious, though some other viruses such as measles are substantially higher. In all cases, early intervention would be essential.
The authors note in their study that the current World Health Organization stockpile of antivirals for avian flu could probably be sufficient to help contain a pandemic in a population like the one in the model, if the stockpile were deployed within two to three weeks of detection.
As part of their study, the researchers consulted with Thai ministry of health officials and concluded that public health workers may decide that TAP, rather than GTAP, is the more realistic strategy, given their resources.
This research effort is part of a network called MIDAS (Models for Infectious Disease Agents Study), supported by the National Institute of General Medical Sciences. A related paper from another group of MIDAS researchers is being published simultaneously in the journal Nature.
American Association for the Advancement of Scienc
Pandemic Current Events and Pandemic News RSSSynthetic virus supports a bat origin for SARS
SARS - severe acute respiratory syndrome - alarmed the world five years ago as the first global pandemic of the 21st century. The coronavirus (SARS-CoV) that sickened more than 8,000 people - and killed nearly 800 of them - may have originated in bats, but the actual animal source is not known.
Study of ancient and modern plagues finds common features
In 430 B.C., a new and deadly disease-its cause remains a mystery-swept into Athens. The walled Greek city-state was teeming with citizens, soldiers and refugees of the war then raging between Athens and Sparta.
Common cold virus came from birds
A virus that causes cold-like symptoms in humans originated in birds and may have crossed the species barrier around 200 years ago, according to an article published in the December issue of the Journal of General Virology. Scientists hope their findings will help us understand how potentially deadly viruses emerge in humans.
First Holistic Guide to Primate Disease Covers Critical Gap in Global Health
Why are so many infectious diseases jumping from animals to humans? Why do we have so little capacity to predict epidemics, or avoid them?
Results of landmark study of HIV vaccine published in the Lancet
Results from the Step study, a test-of-concept efficacy study of a Merck & Co., Inc. HIV vaccine candidate, were published online today in two papers in The Lancet. These analyses of the Step study are being conducted, presented and published to inform the continued search for an effective HIV vaccine.
Protein 'tubules' free avian flu virus from immune recognition
A protein found in the virulent avian influenza virus strain called H5N1 forms tiny tubules in which it "hides" the pieces of double-stranded RNA formed during viral infection, which otherwise would prompt an antiviral immune response from infected cells, said Baylor College of Medicine researchers in an online report in the journal Nature.
XDR-TB: Deadlier and more mysterious than ever
New research has found that XDR-TB is increasingly common and more deadly than previously known. Extensively drug-resistant tuberculosis (XDR-TB) is a growing public health threat that is only just beginning to be understood by medical and public health officials.
Polarized light guides cholera-carrying midges that contaminate water supplies
Cholera is a major killer and since the first pandemic in the early 19th century it has claimed millions of lives. According to Amit Lerner from The Hebrew University of Jerusalem, Israel, the lethal infection is harboured by an equally infamous insect: chironomids (midges).
New intranasal influenza vaccine triggers robust immunity with significantly less antigen
A single administration of a novel, nasally delivered influenza vaccine elicited immune responses in ferrets that were more than 20 times higher than those generated by two injections of the currently approved vaccines, according to a study by NanoBio Corporation.
Masks, hand washing, prevent spread of flu-like symptoms by up to 50 percent
Wearing masks and using alcohol-based hand sanitizers may prevent the spread of flu symptoms by as much as 50 percent, a landmark new study suggests.
More Pandemic Current Events and Pandemic News Articles
 | Pandemic by Daniel Kalla Genesis of a PlagueRight now, in a remote corner of rural China, a farmer and his family are sharing their water supply with their livestock: chickens, ducks, pigs, sheep. They share the same waste-disposal system, too.Bird viruses meet their human counterparts in the bloodstreams of the swine, where they mix and mutate before spreading back into the human population. And a new flu is born....Dr.... |
 | Little Book of Pandemics by Peter Moore As the world waits once again to see if the latest virus will decimate the population, The Little Black of Pandemics looks at the greatest natural killers of all time. This concise and intelligent look at the most deadly viral and bacterial diseases includes expert opinion on likely future outbreaks, method of contagion, identification of systems, and likelihood of survival. Includes... |
 | Pandemics and Global Health (Global Issues) by Barry Youngerman This is a comprehensive resource on the pandemics that threaten our world.Throughout history, pandemics have rapidly spread across national and continental borders to inflict an insurmountable toll on human life and suffering. From the Black Death in Asia and Europe to the smallpox and polio outbreaks that decimated the Americas, to the contemporary concerns over HIV/AIDS and the avian flu,... |
 | A Cruel Wind: Pandemic Flu in America 1918-1920 by Pettit, Dorothy A. The flu pandemic that began in 1918 touched with illness virtually every family in America. It was a devastating time, far overshadowing the carnage of World War I as the pandemic killed more people in less time than any disease before or since. With 25% to 30% of the worlds population having clinically apparent illnesses and a mortality rate of 2.5% - 5%, it is believed that more than 675,000... |
 | The AIDS Pandemic: Complacency, Injustice, and Unfulfilled Expectations by Lawrence O. Gostin In this collection of essays, Lawrence O. Gostin, an internationally recognized scholar of AIDS law and policy, confronts the most pressing and controversial issues surrounding AIDS in America and around the world. He shows how HIV/AIDS affects the entire population--infected and uninfected--by influencing our social norms, our economy, and our country's role as a world leader. Now in the third... |
 | Flu: The Story Of The Great Influenza Pandemic by Gina Kolata When we think of plagues, we think of AIDS, Ebola, anthrax spores, and, of course, the Black Death. But in 1918 the Great Flu Epidemic killed an estimated 40 million people virtually overnight. If such a plague returned today, taking a comparable percentage of the U.S. population with it, 1.5 million Americans would die.In Flu, Gina Kolata, an acclaimed reporter for The New York Times, unravels... |
| FLU, Story of the Great Influenza Pandemic of 1918 & Search for the Virus That Caused it by Gina Kolata | |
 | Combating the Threat of Pandemic Influenza: Drug Discovery Approaches Drug discovery for influenza antivirals Priorities for combating pandemic influenza include rapid detection and identification, the quick administration of available drugs to treat the infection, the development of new antivirals, and the development of vaccines. Since lead-time may be required to produce an effective vaccine, antivirals would serve as a key first line of defense in... |
 | Protecting Your Business in a Pandemic: Plans, Tools, and Advice for Maintaining Business Continuity by Geary W. Sikich A pandemic is an epidemic that covers a huge swath of the country or even the world. And it's just as scary as it sounds: For example, it's estimated that up to a third of the U.S. population could fall ill in an Avian flu pandemic, costing the U.S. economy alone up to $675 billion. Worse, pandemics shatter lives and businesses and tend to rock society to its foundations. But humanity has been... |
 | The AIDS Pandemic: The Collision of Epidemiology With Political Correctness by James Chin This book exposes the extent AIDS programs developed by international agencies and faith-based organizations are more socially, politically, and moralistically correct than epidemiologically accurate or relevant. This is the first book to provide an objective assessment of the AIDS pandemic, offering clear and rational conclusions drawn to challenge the position of UNAIDS and most AIDS... |
| © 2008 BrightSurf.com |