West Nile virus (WNV) annual infographic, 2018

Organization: Public Health Agency of Canada

Date published: 2020-04-03

Related topics

• Surveillance of West Nile virus
• West Nile virus and other mosquito-borne diseases surveillance report: Annual edition (2018)

What is the risk

• West Nile virus (WNV) is the leading cause of domestically acquired mosquito-borne diseases (MBDs) in Canada.

Who's at greater risk

• Advanced age and people with pre-existing medical conditions such as diabetes, cancer, and heart disease are at greater risk of WNV neurological syndrome.

How to manage

• There is no specific treatment or vaccine for WNV.
• Patients are treated for their symptoms.

WNV transmission

• Birds that are infected with WNV can spread the disease to the mosquitoes that bite them. These mosquitoes then spread the virus to humans, animals and back to bird populations. Only birds and mosquitoes can carry on the cycle of WNV. Humans and animals cannot spread the virus to other humans or animals.

Facts reported in 2018

• 170 dead wild birds tested positive for WNV.
• 571 mosquito pools tested positive for WNV.
• 123 horses tested positive for WNV.
• A higher number of WNV-positive birds, mosquitoes and horses were observed when compared to the previous 5 years.
• 432 humans tested positive for WNV in Canada. Of these humans, 29 people died from WNV infection and 238 people suffered neurological illnesses.
• The reported number of WNV-positive humans (probable and confirmed diagnoses) in Canada has continuously risen since the year 2014. There was a slight decline in the number of reported cases between 2013 and 2014.

Other MBDs

• 72 human cases of California serogroup viruses (CSGV) were detected in Canada.
• 13 horses tested positive for Eastern equine encephalitis virus (EEEV) in Canada.

Public health recommendations

• Avoid becoming infected with WNV and other MBDs by:
  • Protecting yourself using insect repellent.
  • Covering exposed skin with long-sleeved shirts and long pants.
  • Reduce surrounding risk by eliminating standing water from bird baths and other objects that can fill with water after a rainfall.
  • Maintain window and door screens to prevent mosquitoes from entering homes and other buildings.