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Bird flu: a reality check

Health experts say we should be more concerned about regular influenza than the avian strain. As the season nears, get a shot.

October 31, 2005|Melissa Healy | Times Staff Writer

WITH the annual flu season bearing down and fears of bird flu in the news, public health officials are girding for battle. Last week, Health and Human Services Secretary Mike Leavitt told Americans "we're preparing" for an outbreak of bird flu in the U.S. But, he added, Americans should be thinking instead about "something that confronts all of us right now" -- regular influenza. He urged all Americans to get be vaccinated, noting that with more than 80 million doses of flu vaccine coming, shots should be available for all who want them.

What's the connection between the seasonal flu and the bird one in the news? Here are answers to frequently asked questions on the topic, based on information from the Centers for Disease Control and Prevention, the National Institutes of Health and the Food and Drug Administration.

What is the flu?

Regular flu -- so-called "seasonal influenza" -- hits the U.S. from early November through February each year, killing about 36,000 and hospitalizing about 200,000. It's caused by the influenza virus, essentially a family of viruses with many different strains. At any one time, just a few strains are circulating among humans. But other strains are always present in birds and other animals such as pigs and horses. These strains aren't usually a problem for people.

Flu viruses are natural shape shifters: They slowly, constantly change, requiring the vaccine to be frequently updated. Still, this year's flu probably will have many characteristics of last year's flu. If you've recently gotten a flu shot or been exposed to last year's virus, your immune system will probably recognize this year's virus somewhat and be better able to fight it off.

How is bird flu different, and why are public health experts worried about it?

There are lots of flu strains in birds; wild birds are the ultimate reservoir for all the influenzas we catch. Usually, those strains don't even harm the birds. But some can cause significant illness and death when they get into domestic poultry.

The strain that has health workers worried right now -- called H5N1 -- has widely infected poultry across several countries of Southeast Asia for some years. More than 120 people who had close contact with sick birds or carcasses have gotten sick. Most troubling, H5N1 appears to be a vicious flu. More than 60 of those people known to have been infected have died.

So far, the H5N1 bird flu can't easily jump from person to person, and thus can't spread widely among humans. But there are several ways that H5N1 could mutate into a virus that does spread and is foreign enough that our immune defenses can't fight it. If that happened, the virus would spread across a swath of the world (causing a so-called pandemic) and even strong, healthy people could become sick and sometimes die.

Is bird flu here? Am I in danger of getting it?

Not now. H5N1 bird flu has not been found in the U.S., either in birds or humans, although the spread of the virus through wild migratory bird populations makes it plausible that the virus could make its way here. Most important, there's no evidence that the frightening mutant described above has materialized.

Will the flu vaccine protect me from bird flu?

No. Each year's vaccine is designed to prime the body's defenses against strains of flu virus circulating now among humans. If the H5N1 bird flu mutates to jump from human to human, it probably wouldn't look anything like the virus that was the basis for this year's vaccine.

So why should I get the flu shot?

Mainly to avoid the regular flu, which can lay you low for days and cause complications such as pneumonia that, for some, can be deadly. Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, says that the more flu viruses you've been exposed to in your life -- either from vaccine or naturally -- the wider the variety of flu strains your immune system will recognize as invaders and fight.

Public health authorities also hope lots of Americans will get flu shots to attract more drug companies to the vaccine business. Only four companies make flu vaccine for the U.S. If more Americans started getting regular flu shots, companies would be more likely to get into the business and the U.S. would be better able to produce vaccine quickly for a novel flu.

What is Tamiflu, and will it protect me from bird flu? Should I get it now?

Tamiflu, also known as oseltamivir, is an antiviral medication. If taken within a few days of the start of symptoms, it can reduce flu's severity and duration. It's one of only two antiviral medications believed -- although not proved -- to help fight H5N1 bird flu. (The other, Relenza, or zanamivir, is trickier to administer.)

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