A Closer Look at Avian Flu

By JENNIFER STERLING THE WALL STREET JOURNAL ONLINE

September 30, 2005 6:57 a.m.

President Bush in September announced the creation of an international partnership aimed at preventing a global outbreak of avian flu, an influenza virus that has jumped from birds to humans and killed about 60 people in Asia. While millions of birds have been killed by the virus or slaughtered by authorities to stem the contagion in Vietnam, Thailand, Indonesia, China, Russia and elsewhere, the extent of human infection has been limited by the virus's inability thus far to easily jump from human to human. The World Health Organization classes the current avian flu, specifically the H5N1 strain, in Phase 3 of its six-phase Pandemic Watch. That means the virus is a new subtype but hasn't yet evolved to the point where it could set off a true human pandemic. But U.N. and U.S. health officials warn that bird flu could mutate and spread from person to person, which could lead to a global pandemic that could kill millions. Niranjan Bhat, an epidemiologist at the U.S. Centers for Disease Control and Prevention, says: "It's not a question of if, but when."

Here are answers to some common questions about avian flu and its effects:

Why are health officials warning about an avian-flu pandemic?

The H5N1 strain of the virus already has two of the three pandemic criteria: It can jump from birds to humans, and then can produce a severe, even fatal, illness in humans. If H5N1 becomes highly contagious among humans -- the third pandemic characteristic -- then a world-wide outbreak could become a reality.

Pandemics can traverse the globe in a matter of weeks and last several months, and the CDC's preliminary predictions figure an avian-flu pandemic could kill between 89,000 and 207,000 Americans. Although the CDC says it can't predict when a pandemic might occur, historically, global flu epidemics occur once a generation. It has been almost 40 years since the last one. (See related infographic.)

Most people who have contracted the virus so far were in direct contact with infected birds. Health officials say there have been only a few instances of probable human-to-human transmission, and in all of those cases the virus didn't spread beyond the second person. At this point, Americans don't appear to be at risk unless they go to a country affected by poultry outbreaks and visit a farm or market with infected fowl.

How does avian flu compare with the normal flu?

Bird-flu symptoms in humans so far have included those typically associated with the flu -- fever, cough, sore throat and muscle aches -- but can also be much worse. The victims in Asia have experienced eye infections, pneumonia, severe respiratory diseases that injure the lungs, other life-threatening complications and death. The symptoms may depend on which bird-flu strain a victim is exposed to, but the mortality rate appears to be strong: Of the 115 cases of human infection confirmed by the WHO since 2003, 59 have resulted in death as of Sept. 22, the most recent figure available.

The CDC says it doesn't yet know which sections of the population would be most at risk, but past pandemics have claimed many victims among young, healthy adults, a demographic that ranges beyond the usual candidates of the flu season's most vulnerable: children and the elderly.

Is it safe to keep eating poultry?

The WHO doesn't consider bird flu a food-borne disease, and people probably aren't infected from eating poultry. The danger is for people who handle infected poultry. Eggs and processed poultry products -- refrigerated or frozen carcasses and the products they go into -- shouldn't pose a risk, the WHO says.

What vaccines and drugs are available?

Currently, there is no publicly available vaccine for H5N1. Avian-flu vaccines are undergoing preliminary testing by the U.S. government, and the National Institute of Allergy and Infectious Diseases says a Sanofi Pasteur vaccine has shown "safety and ability to generate an immune response" in early trials. But it isn't clear when the testing will be completed. And while Sanofi Pasteur, the vaccine unit of Sanofi-Aventis SA, says it plans to have the needed ingredients ready by the end of the year, the government will still have to decide on how many doses a person needs. Then the vaccine would still have to be licensed and the individual doses filled.

Chiron Corp., meanwhile, plans to deliver its vaccine for H5N1 to the government for evaluation by year end. If global health authorities declare an avian-flu pandemic to be in progress, vaccine manufacturers would ramp up production. To ensure a rapid response at the start of a pandemic, the WHO and some governments are creating stockpiles of antiviral drugs used to treat infections. Among the drugs being stored up in the U.S. is Tamiflu, which is already used to treat the seasonal flu viruses. Studies suggest Tamiflu, made by Roche Holdings AG, works against bird flu, the CDC says.

How can I prepare for an outbreak?

The CDC suggests that people get the traditional flu vaccine manufactured each year ahead of the flu season, even though it doesn't offer immunity to H5N1. In part, that's because it is in a person who contracts bird flu when he or she already is infected with a normal flu strain that the avian virus could mutate into one able to leap from human to human. The best measure to protect against the regular flu is hand washing, health officials say. If you're sick, stay at home.

If a pandemic occurs, check the CDC Web site (www.cdc.org) to find out the most recent information. In past epidemics, people rushed to buy face masks but the CDC says there has been no scientific data supporting the theory that these masks decrease the risk of transmission or infection of avian flu.

I'm traveling to a country where there have been reported outbreaks. What precautions should I take?

If you're traveling to countries where there have been cases of bird flu, avoid poultry farms, contact with animals in food markets and any surfaces that appear contaminated with feces from poultry or other animals. Clean your hands often with soap and water or waterless alcohol-based hand-rubs. All foods from poultry, including eggs, should be thoroughly cooked. Tamiflu may not be readily available overseas, and the State Department encourages Americans traveling or living abroad who are interested in obtaining this medication to consult their physician.

If you've traveled to an affected area and think you have avian flu, first off, don't panic. Avian flu hasn't appeared in humans in the U.S. or in Europe. But if you're suffering from a respiratory illness accompanied by a fever and have recently returned from one of the countries affected, then seek medical attention and explain where you have been.

For the most up-to-date travel advisories, visit the CDC's travel site at www.cdc.gov/travel.

PREVENTING A PANDEMICSee complete coverage of avian flu, including an interactive graphic on the science of the virus and a look back at major flu epidemics.