Mosquito-Borne Diseases

How is WNV spread? 

Symptoms 

8 out of 10 people infected with West Nile virus do not develop any symptoms. Symptoms of WNV usually appear within 2 to14 days after being bitten. About 1 in 5 people who are infected will develop a fever with other symptoms such as headache, body aches, joint pain, swollen glands, vomiting, diarrhea, or rash. Most people with febrile (fever) illness due to WNV recover completely, but fatigue and weakness can last for weeks or months.

More serious symptoms are rare but can occur, especially in older adults, and in adults who are immunocompromised. Seek medical attention if you have any of the following symptoms after being bitten by a mosquito:

• high fever
• rapid onset of severe headache
• stiff neck
• confusion or drowsiness
• paralysis or muscle weakness
• tremors
• convulsions
• vision loss
• numbness

There is no specific treatment or vaccine for West Nile virus infection in humans. Patients are treated for their symptoms. 

Protect yourself and your family from mosquito bites 

• Apply a Health Canada approved insect repellent containing DEET or Icaridin to exposed skin and clothing and consider wearing permethrin-treated clothing.
• Wear long pants, a long-sleeved shirt, shoes, and socks to protect exposed skin.
• Wear light coloured, tightly woven, loose-fitting clothing. Mosquitoes are attracted to dark colours and can bite through thin clothing.
• Make sure that screens for doors and windows have no holes and fit tightly.
• Stay out of wooded areas during dawn and dusk.

Control mosquitoes outside your home or around your property 

Mosquitoes need water to breed and can lay their eggs in small amounts of standing water. It takes about four days for the eggs to grow into adults.

Help eliminate mosquitoes around your property by reducing and eliminating areas or objects that can accumulate or retain water: 

• Routinely drain standing water from items like recycle bins, garbage cans, buckets, planters, toys, and flowerpot saucers.
• Remove unused items (for example old tires) from around your property that may collect water.
• Change the water in bird baths, pet bowls, children’s wading pools, and livestock watering tanks frequently.
• Keep swimming pools clean and properly chlorinated; remove standing water from pool covers.
• Clean out eavestroughs regularly; remove leaves and debris that may prevent the drainage of rainwater.
• Cover rain barrels with mesh screens.
• Keep bushes and shrubs clear of overgrowth and debris (Adult mosquitoes like to rest in dense shrubbery.)