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Climate change and malaria


Malaria is spread by mosquitos, which thrive in warm, wet climates
Malaria is spread by mosquitos, which thrive in warm, wet climates

Alexandra Pope, staff writer

June 7, 2011 — Malaria remains one of the leading causes of preventable illness and death worldwide, even in Canada, and according to one expert, climate change could actually increase the prevalence of the disease.

Mosquitoes thrive in the wake of floods and major rain events, which could become more common with climate change
Mosquitoes thrive in the wake of floods and major rain events, which could become more common with climate change

Malaria is most commonly transmitted by mosquitoes, which are very sensitive to precipitation and humidity.

Dr. Kevin Kain, a professor of medicine at the University of Toronto and director of the Sandra Rotman Laboratories at the University Health Network, says an increased number of hurricanes and floods and an overall warming trend as a result of global climate change could affect mosquito populations and their ability to spread malaria.

“Natural events can have profound impacts on mosquitoes -- how rapidly they breed, how rapidly malaria develops in the mosquito,” Kain explained.

In 20°C heat, it takes three to four weeks before an infected mosquito is able to transmit the malaria parasite to a human. But warm the ambient temperature by a couple of degrees, and the malaria parasite matures more quickly in the gut of the infected mosquito, enabling it to pass on the infection sooner.

Combine that with extreme weather events like hurricanes or floods -- which create favourable conditions for mosquito breeding and could become more common with climate change -- and the extent and persistence of malaria outbreaks could be greatly impacted, Kain said.

Cover up exposed skin and use bug spray to avoid bites from potentially malaria-carrying mosquitoes
Cover up exposed skin and use bug spray to avoid bites from potentially malaria-carrying mosquitoes

While the greatest impact would occur in countries where malaria is endemic (naturally present), Canada could also see a rise in the number of imported cases, Kain said.

Canada already has one of the highest rates of imported malaria among developed countries -- three times the reported per capita rate in the United States.

The reason, Kain said, is our high immigration rate: “Toronto is the most culturally diverse city in the world. An interconnected population means a lot of travel to areas where malaria is naturally found.”

The good news is malaria is easily preventable. Kain offers the following tips for protecting yourself abroad:

  • Know your destination. Find out the malaria risk in the country and region you're travelling to. That will determine the level of protection you'll most likely need.
  • Cover up. Mosquitoes feed at dusk and dawn, so cover up as much as possible at those times and coat any exposed skin with bug spray. Depending on the mosquito risk in your travel area, you may also want to sleep under a treated bed net.
  • Use anti-malarial medication. If you're heading to a region with a high risk of malaria, ask your doctor for a prescription of anti-malarial drugs. They're extremely effective and the new generation of medications has fewer side effects, Kain says.

    With files from Lyndsay Morrison

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