| What exactly is West Nile Virus?
What’s the big deal about West Nile Virus? Why do people in the U.S. only get West Nile Virus in the summer? Why are there outbreaks of West Nile Virus every year? |
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What exactly is West Nile Virus? |
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 West
Nile Virus (WNV) is a type of virus that attacks the central nervous
system. It is known as an arbovirus. That means that it is transmitted
by blood feeding arthropods (a big name for creepy-crawlies like mosquitoes,
sand flies, no-see-ums, and ticks). 
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What’s the big deal about West Nile Virus? I thought only a few people got sick. |
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 You
know your stuff! That’s right--only a small number of people in
the U.S. have gotten sick. But we didn’t know that at first. It
was big news for a few reasons. First, no one’s really sure how
it got here. West Nile Virus is native to Uganda, a country in Africa.
(The Nile starts in Uganda, which is how West Nile Virus got its name.)
Uganda is more than a hop, skip, and jump from New York City, so no
one expected it when WNV just showed up on the Big Apple’s doorstep.
The CDC has some ideas how it might have gotten here—it might
have hitched a ride in an infected mosquito that came over with food,
people, or animals—but no one’s completely sure, even today.
It was scary because some people were getting really sick, and a few people died. And because the virus seemed to come out of nowhere, doctors and scientists didn’t know what to expect. Was it going to pop up in every city? Was it going to make lots of people get sick? How could we stop it from spreading? Fortunately, we know now how to keep it from spreading out of control, and we know only a small number of people who get it get sick. But these were questions that people were asking when the virus first hit New York. The CDC needed the answers—fast.
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Why do people in the U.S. only get West Nile Virus in the summer? |
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 People
only get WNV when they’re bitten by a mosquito that has bitten
an infected bird. So people can only get WNV when mosquitoes are active
and biting people. In most of the United States, mosquitoes are only
active in the summer.
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Why are there outbreaks of West Nile Virus every year? |
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One specific type of mosquito carries WNV – and
it can live for a very long time for a mosquito – including over
the winter. The female Culex mosquito is the main culprit. When the
summer comes, the Culex mosquito infects birds with the virus, which
starts the whole cycle all over again. |