There's still a lot about bird flu that remains a mystery. But thankfully, the long expected pandemic the ailment was expected to produce several years ago has yet to materialize. Here's what we know about the so-called H5N1 strain.
Bird Flu Q&A
Q: What is bird flu?
A: The term "bird flu" generally describes one of several influenza viruses that birds can carry. But several types can also infect humans. These are different in makeup from the usual human flus.
Q: What are the symptoms of bird flu in humans?
A: They can include typical flu-like symptoms, like fever, cough, sore throat and muscle aches, as well as eye infections, pneumonia and severe respiratory illness.
Q: How do humans get bird flu?
A: Right now, authorities believe humans primarily get bird flu from contact with excretions from infected birds, not from other people with the illness. Common victims are people who handle poultry on farms or at live markets. There is one known case of it spreading from one person to another.
Q: Why is bird flu receiving so much attention?
A: A particular type of bird flu, known as H5N1, is seen as a candidate to cause a global flu pandemic if it mutates into a form capable of spreading easily from person to person. Because people have not developed immunity to H5N1, unlike the usual strains of human flu, it could have more severe effects on a greater number of people.
Q: Is bird flu the only possible source of a flu pandemic?
A: No. A pandemic could break out should any dramatically different new flu virus emerge. The last century saw three: in 1918, 1957 and 1968. The 1918 pandemic, caused by a bird flu that jumped to humans, killed at least 40 million people; the later outbreaks killed far fewer but still caused widespread disruption.
Fear of a pandemic is also heightened because it has been four decades years since the last one, and it is thought that new flu strains capable of causing a pandemic emerge every 30 years or so.
Estimates of the death toll from a new pandemic vary wildly, and depend on the level of organized response to an outbreak. Ordinary winter flu kills between 500-1,500 Canadians every year.
Q: How can doctors detect bird flu?
A: With a blood test of a person suspected of having it.
Bird Flu Facts
There are dozens of known flu strains, named for two proteins each virus carries. H5N1 refers to an avian flu strain that emerged in Hong Kong in 1997, killing or forcing the destruction of 1.5 million chickens, ducks and geese, infecting 18 people and killing six. The World Health Organization says the quick slaughter of all potentially infected birds may have averted a pandemic.
H5N1 is considered the biggest direct disease threat to humanity because it mutates rapidly and can also acquire genes from other viruses, making it a potential human pathogen.
Experts estimate that if it acquires the ability to infect people easily and spread from person to person efficiently, it will make more than 25 million people seriously ill and will kill as many as 7 million.
Other models show the virus would make 50 percent of people where it is circulating ill, and 5 percent could die.
All influenza viruses change quickly, which is why the standard flu vaccine must be changed every year. H5N1 is particularly good at changing. Experts fear it may acquire a key gene from a flu virus that already easily infects humans and become a highly contagious and deadly strain.
Birds that survive infection with H5N1 excrete the virus for at least 10 days, orally and in feces, making it highly likely to spread. Migratory birds, usually wild ducks, are the natural "reservoir" of avian influenza viruses, and usually do not become sick when infected. Domestic poultry, including chickens and turkeys, die quickly when infected.
Source: Reuters
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