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Panic Over Pandemic?

November 3, 2005 By:
Frank Rosci, JE Feature
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With cases of Avian - the so-called "bird" flu - confirmed recently in wild birds in Turkey, Romania and Mongolia, health officials in the United States are taking necessary steps to educate citizens about the disease, while work toward creating a vaccine against the potentially deadly virus proceeds at a rapid pace.

Avian flu - the H5N1 strain of influenza A, which surfaced first in Hong Kong in 1997 and in China in 2003, where it claimed dozens of victims - can be passed from a wild bird infected with the virus to humans and certain animals, such as chickens, without the infected "carrier" bird changing its genes. That's the good news, because as long as there isn't gene mutation, which hasn't happened yet, the disease can't be passed generally from person to person.

At this time, the only widespread way people are being affected is by coming in direct contact with infected carrier and liveflock birds.

According to the World Health Organization, the United Nations' specialized group for health headquartered in Geneva, wild waterfowl are considered the natural reservoir of all influenza-A viruses, which they have probably carried, with no apparent harm, for centuries.

"Considerable circumstantial evidence suggests that migratory birds can introduce pathogenic H5 and H7 viruses to poultry flocks, in which the viruses then mutate to the highly pathogenic forms," according to a recent WHO statement. Once poultry are infected, the virus is 100 percent deadly within 48 hours.

The overwhelming concern, of course, is that the disease will mutate to the point in poultry flocks where it will be passed readily to humans, and then from one person to another, causing a worldwide pandemic - an event described as a fast-moving epidemic that occurs over a general or whole geographic area, and affects vast numbers of people.

"People should be informed, but not worry," stated Mark Katz, M.D., medical epidemiologist in the influenza branch of the Centers for Disease Control and Prevention in Atlanta.

"The federal government is working at several levels to prepare for the possibility of an influenza pandemic from Avian flu, with the Department of Health and Human Services coordinating planning across the department - that is, with the CDC and other agencies' with other federal departments, and with domestic and international partners," he added.

During the 20th-century, he said, the emergence of new influenza-A virus subtypes caused three pandemics, which spread around the world within a year of being detected. "Many scientists believe it is only a matter of time until the next influenza pandemic occurs," noted Katz.

The 20th century's three pandemics were the Spanish flu in 1918, when the H1N1 virus killed 20 million to 50 million people worldwide, including 500,000 in the United States; the H2N2 virus of the 1957-58 Asian flu that claimed 70,000 Americans; and the Hong Kong flu or virus H3N2, which killed 34,000 Americans in 1968-69. This one still circulates and kills some 36,000 Americans each year.

"An influenza pandemic occurs when a new influenza-A virus either appears in the human population and causes serious illness, then spreads easily from person to person worldwide, also causing death," explained Katz.

Pandemics, he said, differ from either seasonal outbreaks or epidemics of influenza because seasonal outbreaks are caused by subtypes of influenza viruses that are already in existence among people, whereas pandemic outbreaks are caused by new subtypes or ones that have never circulated among people, or that have not done so for a long time.

"It's fair to say that like most infectious diseases, those who are immune-compromised, and either older or younger, would be more susceptible to infection. But because we have no natural immunity to pandemic viruses, all people are at risk."

As a precautionary measure, said Katz, President Bush has included "influenza caused by novel or re-emergent influenza viruses that are causing, or have the potential to cause, a pandemic" in his executive order that covers "quarantinable communicable diseases."

That order also gives the DHHS legal authority to isolate ill travelers, such as airline passengers, but this would happen only if the person refused to cooperate with health officials, said Katz.

He sounded a note of caution: "If travelers are headed to parts of Asia, the CDC recommends avoiding bird markets and bird farms. Also, people should eat only cooked poultry products."

As for when the H5N1 virus might reach the United States, Katz said there was no way of knowing: "There are many ways all viruses spread. For Avian flu, infected birds shed flu virus in their saliva, nasal secretions and feces. Most cases of bird-flu infection have resulted from contact with either infected poultry or contaminated surfaces.

"So far, spread of the virus from person to person has been rare, and spread has not continued beyond one person. However, because all influenza viruses have the ability to change, scientists are concerned that the H5N1 virus could one day be able to infect humans, and spread easily from one person to another," he said.

At the University of Pennsylvania Medical Center, infectious-disease expert Neil Fishman, M.D., director of the Department of Health-Care Epidemiology and Infection Control, and of the Antimicrobial Management Program, said that an Avian-flu vaccine is in the works and should be ready, including having been tested, in about a year, the same length of time he expects it will take for Avian flu to reach the states.

"Before then, everyone should get a standard flu shot this year. That would accomplish two things: First, it could help to prevent a pandemic while acting to lessen the effects of Avian flu; and second, make it more difficult for Avian flu to mix with the common type of flu. Gene-mixing is one of the ways bird flu mutates," Fishman explained.

He made two emphatic points about the drugs Relenza and Tamiflu that seem to be somewhat effective against Avian flu. "People should not take these at will - if they develop a fever, for example, or think they have other flu-like symptoms. Because if the condition isn't Avian-flu related, doing so will only help to make the disease resistant to the drugs.

"People should see their doctor first. And not hoard drugs. That only makes it much more difficult for others to get them," said Fishman.

From a sanitary standpoint, he recommended doing the practical, prudent things that people's parents taught them to do to stay healthy, such as washing hands frequently and discarding used tissues immediately.

To date, he acknowledged, over the last two years there have been 115 known cases of Avian flu worldwide, and 60 people have died because of it.

 

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