November 4, 2005

Avian flu: questions and answers

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William Schaffner, M.D.

Avian flu: questions and answers

Tom Talbot, M.D.

Tom Talbot, M.D.

The previous century saw three global influenza pandemics. The most serious of these, occurring in 1918, caused at least 50 million deaths worldwide. Referred to as the Spanish flu pandemic, that outbreak is still a source of fascination and horror for historians and public health professionals.

It has been 37 years since the last global flu pandemic and many health professionals speculate we are overdue for an entirely new strain of the flu virus to circle the globe.

The flu virus considered most likely to be the next to make this trip is one of the avian strains, which owe their origins to incubation in bird populations. In the small number of East Asians who contracted avian flu thus far, more than half have died from the illness.

The threat of the next pandemic, when it will arrive, and how severe it will be, has been a point of great speculation for infectious disease specialists around the globe over the last decade. Thanks to the steady drumbeat of recent news coverage, an awareness — and in some instances outright fear — of a potential avian flu pandemic has now burrowed into the consciousness of the American public. Earlier this week, President George Bush outlined a $7 billion strategy to prepare for a pandemic outbreak that includes stockpiling vaccines, speeding the vaccine development process and enhancing state and local governments' emergency response capabilities.

While infectious disease specialists have had many years to educate themselves, speculate and theorize on the potential impact of a global flu pandemic, most people who are just learning of the threat have many unanswered questions.

Two VUMC infectious diseases specialists, William Schaffner, M.D., professor and chairman of the Department of Preventive Medicine, and Tom Talbot, M.D., assistant professor of Medicine and Preventive Medicine, who have been keeping a watchful eye on avian flu activity in East Asia and Eastern Europe, addressed questions they have been answering lately for the news media, friends and fellow health professionals.

What is Avian flu and how is it different from regular flu?

Avian flu is exactly that, it's a new strain of the flu virus which resides only in birds. There have been a handful of cases where transmission of this virus from birds into humans has occurred in Southeast Asia. These transmissions have occurred only in individuals who have had close, prolonged contact with infected birds or the live poultry markets common in this part of the world.

If this new strain of flu were to develop the ability to efficiently move into the human population the consequences could be considerable. No human, save for the 20 or 30 East Asians who were infected and have survived, possess any immunity to this virus. From a viral standpoint it's like starting over with a blank slate where no one would be safe.

How worried should I be?

Right now the U.S. public should not be worried. This virus has not been seen anywhere in the Western hemisphere. The virus does not currently have the capacity to move efficiently into the human population and then move from person to person. Until the virus develops this ability — if it ever does — your chances of being infected are virtually zero.

Then why is anyone worried?

There were three major influenza pandemics in the previous century. These pandemics occurred in 1918, 1957 and 1968. It's been over 35 years since the last one, which makes influenza experts nervous thinking another major pandemic is overdue. We don't know whether the next pandemic may be due six months from now, six years from now or maybe 20 years from now. We just can't tell.

However, it's now clear through modern molecular genetic science that all three of these viruses which caused the three flu pandemics in the 20th century originated in Asia from avian (bird) flu viruses. The similarity to what's happening now with the avian flu virus has the attention of infectious diseases specialists.

The 1918 virus apparently mutated spontaneously, moving from birds into humans, and with the ability to spread easily from human to human. The 1918 pandemic was the worst. A worst-case scenario would repeat this chain of events with a strain of the flu virus which proves equally as deadly. However, while the potential is there, none of this means that if we have another pandemic it will be as bad as 1918.

People in more than one part of Asia have contracted avian flu. If the virus doesn't spread from person to person, how is the avian flu virus spread?

World health officials, who are watching all this very closely, have found the avian flu virus traveling from one province of Southeast Asia to another, and now into Eastern Europe, through birds traveling along migratory routes. Among other methods of transmission, the virus is excreted through the feces of these migratory birds, which during their travels come into close contact with domestic poultry and other birds in these regions.

Can I get Avian flu by eating chicken and chicken products?

Absolutely not. Avian flu is not spread through the consumption of chicken or chicken products, but through exposure to live chickens or their excretions. In addition, the U.S. poultry supply is very safe. Unlike the poultry markets and poultry handling practices in Southeast Asia, the U.S. poultry industry is a closed system. The birds are housed in closed, covered facilities and are handled in closed processing facilities. Even if the avian flu virus were to move onto our shores, chickens raised for consumption in the U.S. do not have contact with migratory birds and therefore should remain safe.

To be safe should I ask my doctor for a prescription of antiviral flu medicine like Tamiflu?

No. Stockpiling this medicine would be a bad idea for two reasons. First, if we have a run on Tamiflu or Relinza (the other flu antiviral) then there might not be enough available to treat people who will truly need it after contracting the regular flu. Secondly, the fastest way for the flu virus to develop a resistance to an antiviral medication is through improper use. Allowing people easy access to these important medicines is setting the stage for indiscriminant use of these drugs, which will lead to drug resistance.

Should I be worried about people traveling here from Southeast Asia and Eastern Europe?

At this time, there have been no definitively documented cases of the avian flu virus being transmitted from person to person. So even if someone with avian flu were to make their way to the U.S. they would not be able to pass the virus on to anyone else.

Is it safe to travel to Eastern Asia?

Yes it is safe to travel to East Asia and Eastern Europe. Until such time as the avian flu virus has been shown to have the capacity to move from human to human, travel to these regions remains safe.

If I travel to East Asia what should I do?

The best advice would be to steer clear of any areas containing open poultry or livestock markets, or any other area where live animals are housed in close proximity to birds. Otherwise, enjoy your trip.

What are the CDC and other U.S. health organizations doing about this problem?

There are several fronts on which this concern is being addressed. First, the U.S. government is stockpiling the two antiviral flu medicines, Tamiflu and Relinza, for treatment purposes should that option become necessary. Secondly, along with Vanderbilt there are research facilities across the U.S. which are currently testing an avian flu vaccine. This vaccine has already been found to be safe in healthy people. Right now studies are being done to determine dosage requirements.

Concerns over the threat of an avian flu pandemic are now squarely on the radar of the White House and the threat is receiving the highest level of attention from top U.S., European and Asian governmental health organizations.

On the local level our Tennessee Department of Health and Metro Health Department, along with area health care providers including VUMC, have developed and tested flu pandemic preparedness plans which would be enacted should a widespread flu outbreak occur.

What can I do?

Right now an avian flu pandemic is only a theoretical risk. This year's influenza season poses a real risk. What you can do right now is to protect yourself and your family from the very real risk of contracting the regular old influenza, which visits us each year. You can effectively do this by getting vaccinated against this year's flu strain.

Remember, each year the flu causes approximately 36,000 deaths in the United States. Many of these deaths could be easily prevented if more people would get vaccinated.