What is bird flu?
Everybody's had the flu at some time in their lives, with its familiar symptoms: aches, chills, fatigue and cough. So why is the "bird flu" making so many headlines?
The deadly virus H5N1 is a strain of influenza normally found only in chickens, turkeys and a variety of other birds. In certain countries, including Vietnam, Indonesia, China, Thailand, Cambodia, Egypt and Turkey, this H5N1 virus has spread to a handful of humans. To date, of the 218 people who have been infected by bird flu, more than half have died. The victims are believed to have contracted bird flu after coming in contact with feces, blood or mucus of infected birds.
At the moment, there is not conclusive evidence that the virus can spread from one human to another. However, this could soon change because the bird flu virus mutates so rapidly. If a mutated strain were able to spread from human to human—an occurrence some medical experts say is inevitable—this highly contagious flu could travel around the globe in a matter of days, infecting every city in every country on the planet
Everybody's had the flu at some time in their lives, with its familiar symptoms: aches, chills, fatigue and cough. So why is the "bird flu" making so many headlines?
The deadly virus H5N1 is a strain of influenza normally found only in chickens, turkeys and a variety of other birds. In certain countries, including Vietnam, Indonesia, China, Thailand, Cambodia, Egypt and Turkey, this H5N1 virus has spread to a handful of humans. To date, of the 218 people who have been infected by bird flu, more than half have died. The victims are believed to have contracted bird flu after coming in contact with feces, blood or mucus of infected birds.
At the moment, there is not conclusive evidence that the virus can spread from one human to another. However, this could soon change because the bird flu virus mutates so rapidly. If a mutated strain were able to spread from human to human—an occurrence some medical experts say is inevitable—this highly contagious flu could travel around the globe in a matter of days, infecting every city in every country on the planet
How does bird flu differ from seasonal flu?
According to Dr. Michael Osterholm, an infectious disease expert from the University of Minnesota, understanding the different kinds of influenza viruses can help explain why bird flu is so potentially deadly.
"There really are, in a sense, three different kinds of influenza viruses," he says. "There is that which naturally lives in wild birds. That virus doesn't really hurt us very often."
The second type of influenza, called seasonal flu, is the one most know. Though it is common, this flu virus kills 36,000 people a year, Dr. Osterholm says.
The third kind of influenza virus is the one that has many people extremely worried. It is a flu virus that has mutated from affecting only birds to one that can infect both birds and humans. "That's when we see a pandemic, or a worldwide epidemic," Dr. Osterholm says. "And that's what we worry about."
Why does a flu virus mutate? "When that virus lives inside a bird, it's uniquely made to live inside the cell of a bird," Dr. Osterholm explains. However, "the influenza virus is one of the sloppiest, most indiscreet, most promiscuous viruses we know. It basically doesn't know how to reproduce itself very well, and it makes mistakes all the time. That's called a mutation. Some of those mutations will actually survive, and when they survive, they actually get closer and closer to allowing it to get inside a human cell. Imagine the chicken virus is a key and the chicken cell is the lock. It gets in easily. The human cell is the lock. The chicken key doesn't work well in it. Over time, the mutations change that key just enough so now it readily gets inside a human cell. That's what we're worried about."
According to Dr. Michael Osterholm, an infectious disease expert from the University of Minnesota, understanding the different kinds of influenza viruses can help explain why bird flu is so potentially deadly.
"There really are, in a sense, three different kinds of influenza viruses," he says. "There is that which naturally lives in wild birds. That virus doesn't really hurt us very often."
The second type of influenza, called seasonal flu, is the one most know. Though it is common, this flu virus kills 36,000 people a year, Dr. Osterholm says.
The third kind of influenza virus is the one that has many people extremely worried. It is a flu virus that has mutated from affecting only birds to one that can infect both birds and humans. "That's when we see a pandemic, or a worldwide epidemic," Dr. Osterholm says. "And that's what we worry about."
Why does a flu virus mutate? "When that virus lives inside a bird, it's uniquely made to live inside the cell of a bird," Dr. Osterholm explains. However, "the influenza virus is one of the sloppiest, most indiscreet, most promiscuous viruses we know. It basically doesn't know how to reproduce itself very well, and it makes mistakes all the time. That's called a mutation. Some of those mutations will actually survive, and when they survive, they actually get closer and closer to allowing it to get inside a human cell. Imagine the chicken virus is a key and the chicken cell is the lock. It gets in easily. The human cell is the lock. The chicken key doesn't work well in it. Over time, the mutations change that key just enough so now it readily gets inside a human cell. That's what we're worried about."
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