Education Materials

Mount Sinai Hospital is a University of Toronto patient care, teaching, and research centre.
Mount Sinai Hospital is a University of Toronto patient care, teaching, and research centre.

Frequently Asked Questions

» Why are mosquito bites a concern?

Mosquitoes are an important vector in the transmission of diseases such as Malaria, West Nile Virus, Yellow Fever, and Dengue Fever. Getting these diseases from a mosquito bite will depend on the geographic prevalence of the disease and the species of mosquitoes in that area. During a mosquito bite, mosquito saliva is injected into the bite as a local anesthetic and anti-coagulant. The female mosquito then proceeds to feed on the host blood. This exchange of mosquito saliva and blood is an excellent opportunity for pathogens to spread from mosquitoes to humans, and from humans to humans using mosquitoes as an intermediate.

» What is the proper use of insect repellent?

  • Apply insect repellent containing DEET (N,N-diethyl-meta-toluamide) to exposed skin whenever you are outdoors. The more DEET a repellent contains the longer time it can protect you from mosquito bites.
  • A higher percentage of DEET in a repellent does not mean that your protection is better—just that it will last longer. DEET concentrations higher than 50% do not increase the length of protection.
  • Repellents may irritate the eyes and mouth, so avoid applying repellent to the hands of children.
  • Whenever you use an insecticide or insect repellent, be sure to read and follow the manufacturer's DIRECTIONS FOR USE, as printed on the product.
  • Do not apply repellents containing permethrin directly to skin. Spray on clothing.
  • Do not spray repellent containing DEET on the skin under your clothing. This is ineffective.

» What clothing is best?

  • When possible, wear long-sleeves, long pants and socks when outdoors.
  • Treating clothes with repellents containing permethrin or DEET will give extra protection, since mosquitoes may bite through thin clothing.
  • Place mosquito netting over infant carriers when you are outdoors with infants.
  • Avoid wearing dark coloured clothing, as this attracts mosquitoes
  • Avoid wearing perfume, as this attracts mosquitoes

» What are peak biting hours?

The hours from sunset to sunrise are peak mosquito biting times. Consider avoiding outdoor activities during these times -- or take extra care to use repellent and protective clothing during evening and early morning.

» What can I do around the home?

  • Install or repair window and door screens so that mosquitoes cannot get indoors.
  • If necessary, use mosquito netting, and check for holes in the net.
  • Help reduce the number of mosquitoes in areas outdoors where you work or play, by draining sources of standing water. In this way, you reduce the number of places mosquitoes can lay their eggs and breed.
  • At least once or twice a week, empty water from flower pots, pet food and water dishes, birdbaths, swimming pool covers, buckets, barrels, and cans.
  • Check for clogged rain gutters and clean them out.
  • Remove discarded tires, and other items that could collect water.
  • Be sure to check for containers or trash in places that may be hard to see, such as under bushes or under your home.

» What does not work?

Vitamin B, garlic, thiamine, and "ultrasonic" devices are NOT effective in preventing mosquito bites.

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Copyright 1999-2007 Department of Microbiology, Mount Sinai Hospital, Toronto, Canada. All rights reserved.