Bird flu: Your questions answered

The possibility of a worldwide pandemic of deadly avian (bird) flu has generated an alarming array of rumors, inflated fears, and false claims. Here are answers to some of the most pressing questions about the true nature of the threat and what you can do to protect yourself and your family.

1. Why is bird flu potentially so dangerous?

This virus, called influenza A (H5N1), is unusually virulent: More than half of the small number of people infected to date have died as a result. And there is little pre-existing natural immunity to the virus in the human population. Finally, the virus is spreading quickly among domestic flocks of chickens and other birds across an expanding range of the world, putting more and more people at risk. Concerned by the tenacity of the virus, the World Health Organization expects it will take several years to stop outbreaks in domestic poultry.

2. How do people become infected?

Chickens and other domestic or wild birds infected with bird influenza shed the virus in their saliva, nasal secretions, and feces. Nearly all of the reported human cases have involved contact with infected birds: butchering or plucking chickens, eating undercooked poultry, or spending time in areas contaminated with the blood or droppings of birds, particularly sick or dying chickens.

3. So, how great is the risk to my family and me?

Very low, at least for now. Most people exposed to sick birds don’t fall ill. While the virus has infected millions of birds worldwide, as of mid-September 2007, there have been only 328 confirmed cases reported worldwide since the disease was first identified. Reassuringly,the risk of transmission from patients to other people has also remained low and, in most cases, is limited to close contacts. Still, experts worry that the evolving virus could swap genes with a human flu virus, making human-to-human transmission much more likely. It’s impossible to predict the likelihood of that happening, or how dangerous such a mutated virus would be. But given the deadly nature of the current H5N1 virus, and its uncontrolled spread among birds, health experts worldwide are trying to prepare for a possible pandemic.

4. Hasn't bird flu already reached the U.S.?

No. The highly lethal strains of H5N1 influenza that arose in Asia have not appeared in any tests of wild birds or domestic flocks in North America. A Canadian outbreak in September 2007 was caused by an H7N3 strain of bird flu that can spread rapidly through chickens. Relatively harmless strains of H5N1 virus have circulated among wild birds in the U.S. since at least 1975. But these so-called "low pathogenic" strains typically cause only minor sickness or no noticeable signs of disease in birds and pose no risk to people.

5. Can pets catch the virus and spread it to their owners?

Since the virus has not yet reached North America, there is little risk at the moment of pets here becoming infected. In other parts of the world, cats and dogs have contracted the virus after eating sick birds or coming in contact with their droppings. And experimentally infected dogs shed H5N1 virus from their noses, so it's possible they could infect people. But so far, no human cases have been traced to infected animals other than birds.

6. How can I tell whether I have regular flu or bird flu?

Your chance of contracting the H5N1 virus is currently almost nonexistent unless you’ve traveled to parts of the world where the virus has been detected and have been near sick birds or have eaten undercooked poultry. That said, here’s how avian flu differs from seasonal flu: While both generally cause high fever and coughing, bird flu does not usually produce the runny nose, inflamed sinuses, or upper-respiratory congestion typical of seasonal flu. Instead, the sickness often advances rapidly to pneumonia, which is the most common cause of death. Doctors can now provide a prompt, definitive diagnosis of bird flu, using a rapid test for the H5N1 virus.

7. How might a pandemic start?

The virus first needs to gain the ability to spread easily from person to person. The initial signs might be an outbreak among caregivers at a hospital or a cluster of cases not linked to contact with birds. Testing virus samples for significant mutations or recombination with human influenza strains could provide advance warning. If a fully contagious virus emerges, it’s almost certain to spread globally. At that point, attention will shift to rapid development and distribution of a vaccine, the supplying of anti-flu medication to affected areas, and other broad public-health measures. Countries might be able to use border closures and travel restrictions to delay the spread of the virus. But given the volume of international air travel, the World Health Organization estimates that a pandemic virus could reach all continents in less than three months.

8. Will there be a vaccine, and how would I get it?

The regular flu vaccine does not prevent bird flu. Researchers have developed candidate vaccines for at least two variants of H5N1. In April 2007 the U.S. Food and Drug Administration approved an H5N1 vaccine, which the U.S. government is stockpiling for emergency use. The manufacturer is not distributing the vaccine commercially. U.S. officials have obtained about 6 million doses and plan to stockpile millions more. Larger quantities of vaccine are not likely to become widely available until several months after the start of a pandemic. That’s because developers must design the final version to closely match the mutating virus before starting large-scale manufacturing. And the capacity of manufacturing plants would likely fall short of the demand for vaccine during a pandemic. So public health authorities would probably reserve vaccines at first for high-risk groups, such as frontline health-care workers and people who’ve been exposed to the virus.

9. Could a pneumonia shot help protect me?

The pneumococcal polysaccharide vaccine, or PPV, protects against bacteria that invade the lungs of people weakened by influenza. But it’s not known whether the shot would provide any protection in cases of bird flu, which can cause deadly pneumonia on its own, without any bacterial infection. The vaccine is currently recommended for people age 65 and older as well as everyone over age 2 who has diabetes, heart disease, kidney failure, or other systemic diseases that might weaken immunity or the lungs. Signs of an imminent bird-flu pandemic would probably make that step more important than ever, even if the benefit hasn’t been proved. Whether other people should get the shot in that situation would be up to the individual and his or her doctor, until more definitive evidence emerges.

10. Do flu drugs or any medications work against bird flu?

Animal studies suggest that two prescription drugs--oseltamivir (Tamiflu) pills and zanamivir (Relenza), an inhaled medication--may reduce the severity of the illness. Limited experience in humans suggests that starting treatment early may boost the chance of survival. However, higher doses and longer treatment may be required for bird flu than for ordinary flu.And in several patients, the H5N1 virus has developed resistance to oseltamivir. Currently circulating strains of the H5N1 virus are resistant to an older class of flu drugs, including rimantadine (Flumadine) and amantadine (Symmetrel), but these still could potentially be used during a pandemic.

11. Should I stock up on the newer anti-viral drugs?

That's a bad idea. You should use oseltamivir and zanamivir only if your doctor confirms the diagnosis. A private home supply could tempt you to take the medicine when it's not needed, for instance, when you just have a bad cold. That needlessly exposes you to possible side effects and, on a broader scale, it may increase resistance to the drug. Moreover, private hoarding could worsen current worldwide shortages and hamper efforts to make emergency supplies available to people who need them the most. As of mid-2007, federal and state governments had warehoused enough flu antivirals to treat 48 million people, and they aim to have enough for 81 million by 2008.

12. Would any supplements help?

Beware of pitches for formulas and supplements claiming to protect you from bird flu. The Food and Drug Administration has taken action to stop the makers of more than a dozen products from making such misleading and unsubstantiated claims. One substance heavily marketed for flu protection, colloidal silver, has no proven use against any illness, and even low doses can eventually build to toxic levels in the body. Some evidence suggests that black elderberry syrup can ease the symptoms of seasonal flu, but no one knows whether it would help with bird flu. And there’s no guarantee that the syrup contains what the label says, since dietary supplements are virtually unregulated by the government.

13. Can masks or anything else help protect me?

Masks can help to a degree and are most useful when used by sick people or those caring for them. In a pandemic, it would make sense to wear one while on trains, buses, and in other crowded places. Simple hand washing can provide significant protection against flu viruses of all kinds. Using soap and warm, running water, rub your hands together vigorously for 15 to 20 seconds before eating or preparing meals and after using the bathroom or blowing your nose. If water and soap are not available, using an alcohol-based gel, such as Purell, is the next best step, just make sure that the alcohol content exceeds 60% to be most effective.

If you do decide to purchase a mask or respirator, keep in mind that while they can look the same, they can vary widely in their ability to filter. Only masks and respirators that have been cleared by FDA, or bear a label from the National Institute for Occupational Safety and Health (NIOSH) as rated N-95 or higher, and that also fit tightly over your nose and mouth, should help prevent inhalation (or transmission) of most virus-bearing droplets from a cough or sneeze. Two FDA approved, N-95, mask-respirators are made by 3M: The 8612F and 8670F masks (about $2 to $4 per mask). The masks are sold under 3M's Nexcare brand in drugstores, pharmacies, and mass retail outlets. Packages of these are available in hardware and building-supply stores and cost about $12 to $25. No matter what FDA or NIOSH approved mask you choose, the FDA recommends that disposable masks not be reused, washed or shared.

For more information or to search for a complete list of masks and respirators approved by the FDA visit www.fda.gov/cdrh/ppe/masksrespirators.html (search can be found at the bottom of the page).

14. What do I need to know about a possible quarantine?

Many public-health authorities question the usefulness of aggressive quarantines. They believe that efforts to round up and confine all exposed individuals would probably be ineffective. The U.S. Centers for Disease Control and Prevention says federally imposed quarantines are likely “only in rare situations,” such as at ports of entry. (For more information, visit the CDC’s Web site: www.cdc.gov/ncidod/dq/isolation_quarantine.) The agency says it would most likely recommend voluntary home quarantines, with exposed individuals checking themselves for fever and reporting early symptoms to public-health authorities. If you're exposed to a sick person, your quarantine time would depend on the incubation period of the particular influenza: about 4 days for seasonal flu, up to 10 days for bird flu. To be on the safe side, the CDC recommends you store a two-week supply of water and food, which can be useful in other types of emergencies, such as power outages and disasters. You should also keep basic health supplies on hand, including pain relievers, stomach remedies, and cold medicines.

15. Is it safe to travel overseas?

Yes, provided you take certain precautions. Check with the Centers for Disease Control and Prevention travelers’ health Web site wwwn.cdc.gov/travel/default.aspx for the latest updates on disease risks and recommendations specific to your destination. Travelers to areas with known outbreaks of H5N1 should avoid contact with chickens, ducks, and geese, live food markets, and other places likely to be contaminated with poultry or other animal excrement. And make sure your food is well cooked: Poultry should be heated until the interior is no longer pink, and eggs until the yolk is firm.

16. Where can I get more information?

In addition to the links cited above, here are two of the most comprehensive and reliable Web sites:

• The U.S. Centers for Disease Control and Prevention: www.cdc.gov/flu/avian.
• The World Health Organization, including an update on human cases by country: www.who.int/csr/disease/avian_influenza/en.