The first human case of West Nile Virus in Waterloo Region in 2015 has been identified. The case is a female adult from Cambridge who is recovering. The first case is confirmation that West Nile Virus activity has begun in the Region and reinforces the need to take precautions.

Image/Perry-Castañeda Library

West Nile virus is usually spread by the bite of a mosquito that has fed on an infected bird.  In very rare cases, West Nile virus can be spread through: blood transfusion, organ or tissue transplants, pregnancy (from mothers to unborn babies), breast milk and exposure of laboratory workers to infected medical specimens.

Symptoms can range from mild to severe. Most people (70% to 80%) who are infected with West Nile virus have no symptoms.

Some people have mild symptoms that can include: fever, headache, body aches, mild rash and swollen lymph glands.

First symptoms usually appear within 2 to 15 days after infection.

Anyone infected with West Nile virus can be at risk of developing more severe symptoms and health effects. Adults 50 years or older and those with underlying conditions or weaker immune systems, however, are at greater risk.

Very few people (fewer than 1 per cent of people infected with the virus) will develop severe symptoms and health effects. In many of these cases, the infection can affect the central nervous system. This is the nervous system tissues in the brain and spinal cord).

The first human case of West Nile virus infection in Canada was reported in Ontario in 2002. In 2014, Canada reported 21 human West Nile virus cases. The worst year for WNV in Canada was 2007 when there were 2,215 cases.

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