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West Nile Virus - Frequently Asked Questions

The following are frequently asked questions about West Nile virus:

What is West Nile virus?

  • West Nile virus (WNV) is a virus that is found in wild birds and carried by mosquitoes. It was first identified in the province of West Nile, Uganda in 1937. Since then it has been identified in Egypt, Asia, Israel, South Africa, parts of Europe and Australia.
  • In 1999, it was present in the United States for the first time, and in the summer of 2001 was discovered in birds in southern Ontario, including Halton.
  • In 2002, human cases were first identified in Canada, including Halton.

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How is West Nile virus spread?

  • Mosquitoes  become infected with West Nile virus when they feed on the blood of infected birds.
  • The virus is carried in the mosquito’s salivary glands.
  • An infected mosquito can then transmit WNV to humans and animals through its bite.
  • The virus is not known to spread from person-to–person contact such as touching, kissing, or caring for someone who is infected. Other modes of transmission are being investigated.

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Who is at risk and what are the symptoms?

  • People of all ages can be infected with West Nile virus and some will have severe illness.
  • Of those who are infected, 80% have no symptoms. Almost 20% of those infected will have West Nile fever, which consists of fever, headache, muscle ache and rash.
  • The most serious illnesses are encephalitis and meningitis, which occur in 1 in 150 infections.
  • Anyone who is infected with WNV can have severe illness. However, the risk of severe illness increases with age. Also, those with chronic diseases or weakened immune systems are at greater risk for severe illness.

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How is West Nile virus treated?

  • There is no specific treatment or vaccine against West Nile virus.
  • Only the symptoms and complications can be treated.
  • Most people recover from an infection.

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How can I protect my family and myself from mosquito bites ?

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What can I do to reduce mosquitoes breeding sites around my home ?

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