MSNBC: Bird flu basics

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http://www.msnbc.msn.com/id/4034127/

FACT FILE Bird flu basics

* Introduction

* What is it?

* Why the concern?

* Transmission

* History

* Symptoms

* Treatment

* Prevention

 

The rapid spread of bird flu, which is not uncommon among chickens

and other fowl, has caught the attention of global health

authorities. Click on the topics to learn more about the illness and

why scientists are so concerned.There are at least 15 different types

of avian influenza that routinely infect birds around the world. The

current outbreak is caused by a strain known as H5N1, which is highly

contagious among birds and rapidly fatal. Unlike many other strains

of avian influenza, it can be transmitted to humans, causing severe

illness and death.

 

Bird flu is not the same as SARS (severe acute respiratory syndrome).

Although their symptoms are similar, SARS is caused by completely

different viruses. Influenza viruses also are more contagious and

cannot be as readily contained as SARS by isolating people who have

the infection.Influenza viruses are highly unstable and have the

ability to mutate rapidly, potentially jumping from one animal

species to another. Scientists fear the bird flu virus could evolve

into a form that is easily spread between people, resulting in an

extremely contagious and lethal disease. This could happen if someone

already infected with the human flu virus catches the bird flu. The

two viruses could recombine inside the victim's body, producing a

hybrid that could readily spread from person to person.

 

The resulting virus likely would be something humans have never been

exposed to before. With no immune defenses, the infection could cause

devastating illness, such as occurred in the 1918-19 Spanish flu

pandemic, which killed an estimated 40 million to 50 million

worldwide.In rural areas, the H5N1 virus is easily spread from farm

to farm among domestic poultry through the feces of wild birds. The

virus can survive for up to four days at 71 F (22 C) and more than 30

days at 32 F (0 C). If frozen, it can survive indefinitely.

 

So far in this outbreak, human cases have been blamed on direct

contact with infected chickens and their droppings. People who catch

the virus from birds can pass it on to other humans, although the

disease is generally milder in those who caught it from an infected

person rather than from birds.

 

If the virus mutates and combines with a human influenza virus, it

could be spread through person-to-person transmission in the same way

the ordinary human flu virus is spread.The current outbreak of bird

flu is different from earlier ones in that officials have been unable

to contain its spread. An outbreak in 1997 in Hong Kong was the first

time the virus had spread to people, but it was much more quickly

contained. A total of 18 people were hospitalized with six reported

deaths. About 1.5 million chickens were killed in an effort to remove

the source of the virus.

 

Unlike the 1997 scare, this outbreak has spread more rapidly to other

countries, increasing its exposure to people in varied locations and

raising the likelihood that the strain will combine with a human

influenza virus. Bird flu can cause a range of symptoms in humans.

Some patients report fever, cough, sore throat and muscle aches.

Others suffer from eye infections, pneumonia, acute respiratory

distress and other severe and life-threatening complications.Flu

drugs exist that may be used both to prevent people from catching

bird flu and to treat those who have it. The virus appears to be

resistant to two older generic flu drugs, amantadine and rimantadine.

However, the newer flu drugs Tamiflu and Relenza are expected to work

- though supplies could run out quickly if an outbreak occurs.

 

Currently there is no vaccine, although scientists are working to

develop one. It probably will take several months to complete and may

not be ready in time to stop a widespread human outbreak, if one

occurs.Rapid elimination of the H5N1 virus among infected birds and

other animals is essential to preventing a major outbreak. The World

Health Organization recommends that infected or exposed flocks of

chickens and other birds be killed in order to help prevent further

spread of the virus and reduce opportunities for human infection.

However, the agency warns that safety measures must be taken to

prevent exposure to the virus among workers involved in culling.

 

Sources: AP, CDC & WHO

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