Western Equine Encephalitis Virus: Advice for travellers

Level 1 - Practise health precautions (more details)

Original publication date: March 5, 2024

Updated: March 5, 2024

Current situation

There is a higher than expected number of Western equine encephalitis virus (WEEV) infections in people and horses being reported in parts of Uruguay and Argentina. There is an increased risk to people in areas with large outbreaks in horses.  

In Argentina, the most affected areas are the provinces of Santa Fe and Buenos Aires.

Disease Outbreak News Western equine encephalitis – Argentina

In Uruguay, the most affected area is the department of San José.

Disease Outbreak News Western equine encephalitis – Uruguay

Western Equine Encephalitis Virus (WEEV)

Western equine encephalitis is a viral infection that is spread to humans through the bite of an infected mosquito. The mosquitoes that spread WEEV bite during the day and night, but are particularly active during dusk and dawn. 

Most travellers are at low risk of getting Western equine encephalitis. Individuals participating in outdoor work or other outdoor activities are at higher risk due to their increased exposure to mosquitoes. 

Most people infected with WEEV do not feel sick, or develop mild illness, such as: 

  • flu-like symptoms
  • fever 
  • headache
  • general weakness

In rare cases, infection with WEEV can cause severe disease, resulting in meningitis (infection of the membranes that surround the brain and spinal cord) or encephalitis (infection of the brain). Symptoms of severe illness may include: 

  • high-grade fever (39.1 to 41 C)
  • severe headache
  • neck stiffness
  • light sensitivity
  • confusion
  • seizures
  • coma

Young children, particularly infants and children under 2 years of age, and older adults are at greater risk of severe illness. 

There is no specific treatment for Western equine encephalitis. Medical care aims to control the symptoms and help with recovery.


Before your trip

Consult a health care provider or visit a travel health clinic preferably at least 6 weeks before you travel to get personalized health advice and recommendations.

Review the Travel Advice and Advisories page for your destination.

Travel advice and advisories by destination

During your trip

There are no vaccines to prevent WEEV infection. 

The best way to protect yourself from when travelling is to prevent mosquito bites at all times. 

  • Properly apply an approved and age-appropriate insect repellent on exposed skin.
  • Consider limiting outdoor activities when the mosquitos are most active, between early evening and early morning, especially in rural areas.
  • Cover up with light-coloured, loose clothing made of tightly woven materials such as nylon or polyester. Wear long pants and tucked-in long-sleeved shirts with closed-toe shoes or boots and a hat.
  • Use mosquito netting when sleeping (day or night) outdoors or in buildings that are not fully enclosed.
  • Consider wearing approved insecticide-treated clothing.

Seek medical care immediately if you develop symptoms similar to those caused by WEEV.

Learn more about:
Personal Insect repellents
Insect bite and pest prevention
If you become sick or injured while travelling outside Canada or after your return

After your trip

Continue to monitor your health after you return to Canada. If you develop symptoms similar to those caused by WEEV, seek medical care immediately and tell them you have been to an area where there is WEEV transmission.

Information for Health Care Professionals 

The Committee to Advise on Tropical Medicine and Travel (CATMAT) has developed a statement on measures to prevent arthropod bites.

Statement on Personal Protective Measures to Prevent Arthropod Bites

Registration of Canadians Abroad

Sign up with the Registration of Canadians Abroad service to stay connected with the Government of Canada in case of an emergency abroad or an emergency at home.

Registration of Canadians Abroad

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