Bird Flu: Frequently Asked Questions
for National Geographic News
|March 22, 2006|
Bird flu is spreading steadily westward from its Asian source and raising anxiety in its wake.
In February alone the deadly H5N1 strain of avian flu affected birds in Italy, Greece, Bulgaria, Germany, Austria, France, Slovenia, India, Iran, and Egypt.
To date the World Health Organization (WHO) has confirmed 184 cases of H5N1 in humans and 103 deaths.
Just how dangerous is the disease? Our frequently asked questions separate bird flu fact from fiction:
What is bird flu?
Avian influenza (bird flu) is an infection caused by contagious viruses that are common among birds. Wild birds may carry these infections, but they typically prove most harmful to domestic fowl like chickens, ducks, and turkeys.
Highly potent forms of the virus can quickly kill 90 to 100 percent of infected birds.
The best known strain of bird flu is a variation of H5N1, a highly contagious and deadly bird virus. This virus has also infected people. The first known human case of bird flu appeared in Hong Kong in 1997. Recently humans have become infected in Indonesia, Vietnam, Thailand, Cambodia, China, Turkey, and Iraq.
(Read Geographic magazine's "Tracking the Next Killer Flu.")
How do humans get bird flu?
Nearly all humans who have been diagnosed with bird flu had close contact with infected domestic birds (chickens, ducks, or turkeys), or areas contaminated with their excrement and secretions.
It's important to remember that this poultry-based virus is not easily transmitted to humans. Frequently, even people who come into contact with infected birds do not acquire the virus.
Can bird flu be passed from person to person?
To date, spread of the H5N1 virus between people has been extremely limited.
Flu viruses undergo regular genetic mutations. Experts warn that if H5N1, or another strain of avian influenza, mutates to become easily transferable from person to person, a global pandemic could occur with catastrophic results. Humans would have no immunity for such a new virus.
So far there is no evidence that such a mutation has occurred or that it is imminent. However, most experts agree that the next global influenza pandemic is on the horizon. The only question is, How soon?
Why doesn't bird flu spread easily from human to human?
Both bird and human flu viruses infect people by attaching themselves to cells in the respiratory tract. Currently, bird and human strains do this in two different locations.
Bird viruses prefer to bind with molecules located deep within the lungs. This remote location inside the body makes it more difficult to spread the bird flu virus by coughing or sneezing.
But scientists warn that the H5N1 virus could adapt and affect cells much higher up in the airway, where human flu viruses typically bind. If that occurs, the chances of a pandemic could be greatly increased.
Can you get bird flu from eating poultry products?
There is no evidence that avian influenza can be transmitted through cooked foodeven if the poultry or poultry products were contaminated with the virus.
In areas currently free of the virus, such as the United States, poultry products can be safely prepared and eaten. Since 2004 the U.S. government has prohibited the importation of poultry from countries affected by avian influenza.
Poultry can also be consumed in countries where avian influenza is present, but precautions should be followed.
Normal cooking temperatures (70ºC/158ºF or higher) are fatal to the virusbut all parts of the bird or egg must be fully cooked at this temperature. People handling or preparing raw poultry must also ensure that juices or blood do not contaminate other food or drink.
What are the symptoms of bird flu?
Many symptoms reported by avian influenza victims are similar to those of seasonal flu: aches, fever, cough, and sore throat.
Additional and more serious symptoms include eye infections, acute respiratory distress, and pneumonia.
A laboratory test is the only way to determine if a human has contracted bird flu.
Is there a bird flu vaccine?
At present, there is no vaccine available to protect against H5N1, though clinical trials are currently testing several prototype vaccines. Seasonal flu vaccines are not effective against bird flu. Vaccine production is complicated by the virus's ability to change forms through genetic mutation, which could compromise previously effective vaccines.
What is my prognosis if I do get bird flu?
Currently the mortality rate is a bit higher than 50 percent of all confirmed cases. But experts suggest that the mortality rate could decline if the virus mutates and begins infecting more people who have ready access to health care.
Health care facilities are a significant factor in bird flu mortality. So far, many infections have taken place in rural regions of nations where health care is not readily accessible. If the virus were to spread to industrialized nations, the fatality rate might well be lower.
How can bird flu be treated?
Laboratory studies suggest that some antiviral medicines are effective at treating the H5N1 virus in humans.
Antivirals can limit the virus's symptoms and help prevent its spread. The medicines oseltamavir and zanamavir have shown promising results in laboratory tests. But additional research is needed to determine which medications could be the most effective.
Influenza viruses can become resistant to drugs, too, so there is no guarantee that any particular medication could remain effective in the event of a pandemic.
Should I avoid travel to nations affected by bird flu?
Currently, the U.S. Centers for Disease Control and Prevention (CDC) does not believe that travelers must avoid countries affected by bird flu.
The CDC does recommend that travelers visiting such countries avoid poultry farms, as well as contact with animals in live food markets and areas contaminated by those animals or their feces. Travelers should also see the CDC's guidelines for eating poultry products in other countries. (See the CDC's Travelers' Health Advisory.)
What other human diseases are known to have stemmed from avian flu?
Recent genetic studies show that the deadly 1918 "Spanish flu," which circled the globe and killed an estimated 20 to 40 million people, developed in birds and was similar to the current strains of bird flu. Both viruses jumped directly from animals to humans.
The 20th century's other major pandemics, in 1957 and 1968, had different originshybrid flu viruses. They were predominantly human viruses that acquired some genes from an avian source.
Should I worry about my cat or dog catching wild birds?
Cats can and have become infected with bird flu. They may acquire the virus by eating the carcasses of infected birds. Birdbaths and other backyard areas could also become contaminated with the virus by bird droppings, which could be ingested in water or inhaled as airborne dust.
Fewer than a dozen cats are known to have become infected with avian influenza. (Read "Bird Flu Kills Domestic Cat in Germany.") Nonetheless in nations were bird flu is present there is a small risk of pets becoming infected and a similarly small risk that they could infect their human owners.
How can I protect my pet birds?
The U.S. government has instituted a ban on the importation of birds and bird products (such as eggs) from Asian nations affected by the H5N1 strain of bird flu: Cambodia, Indonesia, Japan, Laos, Kazakhstan, Malaysia, China, Romania, Russia, South Korea, Thailand, Turkey, Ukraine, and Vietnam. (As of December 29, 2005).
If avian influenza reaches your area, bringing pet birds inside and out of contact with wild animals should offer protection from the disease.
Do wild birds carry bird flu?
Scientists aren't certain what role migratory birds play in the spread of avian influenza. Waterfowl naturally carry such viruses, often with no ill effects to themselves. However, wild birds can introduce flu viruses into domestic bird populations.
Experts are monitoring migratory flyways in an attempt to chart the spread of the H5N1 strain of bird flu. (Read "Alaskan Ducks Tested for Bird Flu.")
What do I do if I come across a dead bird in my yard?
The CDC suggests observing wild birds from a distance. If you encounter a diseased or dead bird, do not pick it up. The safest course would be to contact your state, local, or federal natural resource agency. If you do make physical contact with wild birds do not eat, drink, smoke, or rub your eyes before cleaning your hands with soap and water.
Is it safe to feed the birds in my yard?
Experts recommend avoiding physical contact with wild birds, but the level of risk may depend on the types of birds in your yard.
Most feeders attract perching birds. Although there have been documented cases of these birds dying from H5N1, they are far less likely to be affected than waterfowl and shorebirds, which are traditional carriers of the virus.
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