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The Current State of Bird Flu
posted by admin on 07/04/06
The most recent update of the Avian Flu including answers to most common questions.
Avian flu has hit three continents, spreading to humans in Asia and Africa and affecting birds and mammals in Europe. The outbreak of the highly pathogenic H5N1 strain, which began in Southeast Asia in 2003, hasn't yet spread to the Americas.
The World Health Organization's toll as of midday April 6 stands at 191 human infections and 108 human deaths, mainly concentrated in Asia and the Middle East. Vietnam has seen the highest numbers in humans, with 93 cases and 42 deaths. Indonesia is the next-biggest hotspot, with 29 cases and 22 deaths.
So far, the only human cases have been traced to direct contact with infected poultry, and most have been in poultry farmers, people who worked in the poultry industry or those who lived in close proximity to poultry. But experts fear that the H5N1 strain could mutate and be transmitted from human to human, setting off a global pandemic that could kill millions.
Here are answers to some common questions about the current state of bird flu:
Why should we be worried?
Humans have very limited immunity to avian viruses like H5N1. Unlike the normal flu, which usually causes mild respiratory symptoms in people, the disease caused by H5N1 follows an unusually aggressive course, with rapid deterioration and high fatality, according to the WHO. Primary viral pneumonia and multi-organ failure are common. In the present outbreak, more than half of those infected with the virus have died, and most cases have occurred in otherwise healthy children and young adults.
The virus's recent spread to Nigeria has raised fears that outbreaks among poultry could become widespread in Africa, given the poor state of surveillance and close contact between poultry and humans. That could provide more possibilities for the disease to mutate into a form that is easily transmitted between humans.
What is the likelihood of that happening?
The current strain of H5N1 hasn't easily spread among people. According to research by teams in the U.S. and the Netherlands that was published in the journal Science in late March, the virus primarily infects cells deep in the human lung, possibly making it difficult for the germ to spread. According to Thijs Kuiken, a veterinary pathologist who directed the research, H5N1 attached to cells deep in the lung, but not cells in the throat, where human-flu viruses multiply. Dr. Kuiken called the finding a possible explanation for why the avian virus doesn't jump easily between people. "It must reach the lower respiratory tract to replicate, and it's harder to spread by coughing and sneezing," he said.
Right now, only isolated human cases of bird flu have been reported. The most important warning signal of a possible pandemic would be if a cluster were to emerge suggesting the virus has changed and has begun to spread by human contact.
The WHO says the risk that H5N1 will mutate into a form easily transmitted among humans will persist as long as opportunities for human infections occur. These opportunities, in turn, will persist as long as the virus continues to circulate in birds, and this situation could endure for some years to come.
How are countries able to cope with a possible flu pandemic?
Scientists say the world's ability to handle the disease is improving. "If a catastrophic pandemic occurred tomorrow, everyone in the world would be unprepared," said Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, in February. But he added: "We're so much better off now than we were six months ago, a year ago."
The WHO says despite advance warning that has lasted almost two years, the world is ill-prepared to defend itself. The organization has urged all countries to develop preparedness plans, but it says only about 40 have done so. WHO has also urged countries to stockpile antiviral drugs, but only 30 have purchased large quantities (and the manufacturer is still filling the orders).
Pharmaceutical company GlaxoSmithKline PLC has begun human testing of two potential vaccines against H5N1 with the aim of having a vaccine in production before the end of 2006. The trials, taking place in Germany and Belgium, will evaluate the vaccines' safety and ability to boost a person's immune response against the virus. Several other drug companies and teams of researchers are also racing to develop a vaccine. U.S. health agencies have awarded contracts to Sanofi-Aventis SA and Chiron Corp. to produce and test vaccines.
What medicines can treat bird flu?
The U.S. Food and Drug Administration has approved two antiviral drugs to fight influenza -- Relenza (zanamivir) and Tamiflu (oseltamivir). Tamiflu and Relenza work by blocking a protein present in every type of flu, neuraminidase (the N in H5N1). If taken within 48 hours after symptoms appear, the drugs have been shown to limit the spread of flu virus in the body, reducing the severity of symptoms and the length of illness. The drugs are highly effective if taken within 12 hours of the first symptoms. In addition, Tamiflu and Relenza are 70% to 90% effective in keeping family members of a sick patient from getting sick themselves.
Since influenza is often complicated by a secondary bacterial infection of the lungs, antibiotics could be life-saving in the case of late-onset pneumonia. WHO has suggested that countries keep adequate supplies of antibiotics.
What can people do to protect themselves?
Good hygiene is important, such as washing hands often, especially after touching public handrails and other surfaces, and keeping hands away from the face and mouth. If bird flu does reach a town, chances are quarantines will be an important way to curb the spread of the disease. Therefore, it might be a good idea to stock pantries with nonperishable food items and other supplies.
The WHO says people can eat poultry as long as it is properly cooked at normal temperatures (no pink parts in poultry and no runny yolks in eggs). The U.S. Department of Agriculture advises to cook chicken at 165 degrees Fahrenheit to make it safe. To date, no evidence indicates that anyone has become infected after consuming properly cooked poultry or poultry products, even when these foods were contaminated with the H5N1 virus.
In Europe, H5N1 appears to be spreading among birds and even to mammals. Is it likely to jump to humans soon?
Veterinary experts say the risk of transmission to commercial poultry and to humans in the EU is substantially less than in East Asia. That's because more resources are available to monitor for outbreaks and to confine poultry stocks, and EU residents tend not to live in close proximity to their poultry, as is more common in East or Central Asia, including rural parts of neighboring Turkey.
The EU has set requirements for its 25 member countries to test wild fowl and help neighboring countries with testing. The European Commission has imposed import bans on live birds and products such as fresh poultry meat and untreated feathers from all countries and regions that have detected and confirmed avian-flu outbreaks. After certain outbreaks, a number of countries, such as Germany and Sweden, have also ordered poultry to be kept indoors to avoid contamination.
Will H5N1 make it to the U.S.? Where and how?
Most experts agree that sooner or later, birds infected with the virus will reach North America. However, the improved availability of drugs, better surveillance and other lessons learned from the disease's spread give some cause for optimism, officials and experts say.
If H5N1 were to make it into the U.S., experts generally believe it could happen in a several ways: via the poultry trade through Canada, Central America or the Caribbean; through caged birds illegally smuggled in; or through the migratory bird flyways. With migratory birds, the entry point would most likely be Alaska.
Sources: WSJ research; The World Health Organization; Associated Press
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