Overview of avian flu

Avian flu: Frequently asked questions
By S. Heather Duncan
TELEGRAPH STAFF WRITER
QUESTION: What is avian influenza?

ANSWER: Avian influenza, or "bird flu," is a contagious disease of animals caused by viruses that normally infect only birds and, less commonly, pigs. Most strains of influenza originate in wild birds and never become deadly to birds or humans. The deadly strain of bird flu now spreading out of Asia is identified by scientists as strain H5N1.


QUESTION: What are the symptoms?

ANSWER: Reported symptoms of avian influenza in humans include fever, cough, sore throat and muscle aches; and sometimes eye infections, pneumonia, acute respiratory distress and other life-threatening complications.


QUESTION: How does it spread, and where has it spread?

ANSWER: Avian flu spreads mostly among migrating waterfowl, such as ducks and shore birds, and through domestic poultry that is not kept isolated from wild birds. The virus has infected birds in more than 50 countries spanning three continents. It has not been found in the United States or the Western Hemisphere.

Birds transmit the virus through saliva, nasal fluid and feces. Human cases of bird flu have mostly occurred after direct contact between people and infected birds.

Last month's deaths of family members in Indonesia, and a few cases of caregivers who caught the flu, seem to indicate that the virus has passed directly from person to person in isolated cases. If so, these infections did not trigger larger outbreaks of a human-spread virus. This may be because it is a deep-lung infection, unlike seasonal flu, which is easily breathed out of the upper lungs, said Dr. Susan Lance, Georgia's state epidemiologist.


QUESTION: Is it safe to eat chicken and eggs?

ANSWER: Poultry is not imported to the United States from Asia. In fact, almost all poultry sold in this country is American-bred, and the bird flu has not been found here. Even if the virus spread to U.S. poultry, there is no evidence that anyone has been infected with the deadly strain of bird flu from eating properly cooked poultry products. The U.S. Department of Agriculture indicates that cooking eggs until firm and chicken until it reaches 165 degrees will kill the virus.


QUESTION: How deadly is bird flu?

ANSWER: The H5N1 strain of avian flu has killed 57 percent of the people diagnosed with it. That's a higher death rate than the 1918 flu pandemic, said Dr. Joseph Swartwout, director of the North Central Health District, which includes Macon, Warner Robins and Milledgeville.

It is also higher than the death rate for Severe Acute Respiratory Syndrome, better known as SARS, which was regarded as a potential pandemic a few years ago with a 43 percent death rate, said district epidemiologist Dr. German Gonzalez.


QUESTION: What would have to happen for bird flu to become a pandemic?

ANSWER: The World Health Organization identifies a pandemic as a worldwide outbreak of a new disease, for which humans have no immunity, that spreads easily among people and causes serious illness. H5N1 is a new disease that causes serious illness, but it is not yet easily transmitted from one human to another, so it is not a pandemic.

It is widely believed that the virus would have to either mutate or cross with a human-flu virus in a person or animal's body, before it could become a pandemic. However, the extent of mixing needed is unclear. In January, sequencing of the genes in the 1918 "Spanish flu," the most deadly pandemic flu in modern times, showed that it contained fewer human genes than originally believed, said Lance. "It was almost entirely a bird virus," she said.


QUESTION: Aren't flu pandemics just an unlikely science-fiction scenario?

ANSWER: Flu pandemics happen regularly. Three struck during the last century: the "Spanish influenza" of 1918, "Asian influenza" in 1957 and "Hong Kong influenza" in 1968.


QUESTION: We've had several health scares in recent years: anthrax, West Nile virus and even a supposed pandemic threat from SARS. How is bird flu any different?

ANSWER: There is no guarantee that the H5N1 strain of bird flu will become a pandemic, but public health experts say the virus has characteristics that make it more threatening. West Nile virus was never as deadly, and anthrax doesn't pass from person to person.

SARS was highly transmissible and it had a long incubation period, Lance said. It was easier to identify SARS carriers before they could infect others because the disease took 10 to 15 days to develop. In contrast, bird flu takes just a couple of days and it is more deadly.

H5N1 also has unusual staying power, Lance said. Despite efforts to eradicate the virus by killing more than 200 million Asian birds, it has persisted since 1996.

"In some ways, the longer a virus like that is out there, the more time it has to make genetic changes dangerous to humans," Lance said.

Avian flu also has greater pandemic potential because there is no vaccine for it and because medical experts have a poor understanding of it, Centers for Disease Control spokesman Von Roebuck said.

However, public health officials are aware that people take disease scares less seriously over time. Karen Ebey-Tessendorf, the North Central Health District emergency preparedness coordinator, said this attitude is similar to hurricane weariness on the coast: People prepare less each time they aren't hit by the big one, but that doesn't mean the next storm won't be deadly.

"People since 9/11 and the anthrax letters (soon afterward) are more in tune with public health disasters than before," Lance said. "I think we have people's attention. Whether we've cried 'wolf' or not, I don't know."


QUESTION: Is there treatment or a vaccine?

ANSWER: There is no vaccine for H5N1. Although they are under development, vaccines are not expected to be finished any time soon. And because the virus is likely to adapt before becoming a pandemic, an effective vaccine could not be developed until months after a pandemic begins, Swartwout said.

Initial bird flu vaccines tested in healthy adults had to be administered in high doses, and it had to be given twice to be effective, said Dr. Jon Abramson, chairman of the CDC Advisory Committee on Immunization Practice. One problem with manufacturing a bird flu vaccine is that vaccines are often cultured using eggs - an obvious problem if the egg supply becomes contaminated, he said.

There are two antiviral drugs, sold commercially as Tamiflu and Relenza, that can reduce severity and duration of illness caused by many kinds of influenza. They must be administered within 48 hours of the onset of illness to be effective. They may improve survival rates for patients with H5N1, but the evidence is limited, according to the WHO.

University of Georgia researchers are working on an alternative to the antiviral drugs: a genetic process that would essentially "silence" the expression of viral genes in the body. The process has already gone through the first phase of human clinical trials, said Ralph Tripp, a UGA professor and director of the Center for Disease Intervention.

"We believe it can be used for human treatment very soon," Tripp said. "We can make enough stockpile for pandemic flu in months, whereas it would take years to make enough Tamiflu."


QUESTION: What can I do to prepare?

ANSWER: Public health organizations are recommending that families assemble "disaster kits" to help prepare for pandemic flu or natural disasters, including at least a three-day supply of water for each member of the
household (a gallon per day per person) and a three-day supply of non-perishable food.

In addition, the U.S. Department of Health and Human Services recommends keeping nonprescription drugs and other health supplies on hand, including pain relievers, stomach remedies, cough and cold medicines, fluids with electrolytes, and vitamins, as well as soap or alcohol-based hand wash, a flashlight, batteries, a portable radio, a manual can opener, garbage bags, and extra tissues, toilet paper, pet food and disposable diapers. Some disposable rubber gloves and face masks might also be useful to have ahead of time.