Increased Mosquito Habitat One Among Many Climate Change Impacts Threatening Public Health

In May 2000 in the town of Walkerton, Ontario, heavy rains swept water containing the O157:H7 strain of E. coli bacteria from a nearby farm into a well of drinking water. For almost two weeks, the two city workers in charge of water quality claimed that there was no danger. Meanwhile, 2300 people fell inexplicably ill and seven died.

City managers Stan and Frank Koebel both faced criminal charges for their part in the slow response to the outbreak. In his report, Justice Dennis O'Connor lambasted the provincial cuts to the Environment Ministry, which lead to the incompetence on the ground level. It was a disaster that could have been prevented had the public officials in charge acknowledged the problem and acted earlier.

At the ICLEI Livable Cities Forum in early April, Public Health Agency of Canada researcher Manon Fluery invoked the specter of Walkerton as a way to illustrate the growing public health risks associated with climate change. Rising water levels, she said, could lead to a growth in gastrointestinal illnesses related to water borne diseases. Extreme weather events that batter aging infrastructure could lead to cross contamination between sewage and drinking water.

And waterborne illnesses aren’t the only public health risk associated with climate change. The most recent report from the Intergovernmental Panel on Climate Change (IPCC) paints a complex and sweeping picture of the near future. It noted several public health risks that have already begun in exposed coastal regions. While not all of those dire predictions have yet made it to Canada, if climate change is allowed to continue at present alarming rates, there is little doubt they will.

According to Nancy Edwards, the scientific director of the Institute of Population and Public Health at the Canadian Institutes for Health Research, the public health effects of climate change will be numerous and wide ranging. She points to housing and mold issues caused of increased flooding like last year’s in Southern Alberta and Toronto. The loss of housing and livelihood, she says, can also lead to widespread mental health issues.

Meanwhile, seniors, children and low-income people without access to air-conditioning in their homes are particularly vulnerable to rising temperatures in cities where heat is less likely to dissipate. In the North, melting permafrost restricts access to food supply and traditional food sources.

Disease-carrying insects have already begun to force their way into new territories. Both lyme disease carried by ticks and West Nile virus carried by mosquitoes has been on the rise. “There’s an indirect consequence that happens,” Edwards says. “It changes the breeding ground for the insects. Then you have changes in bird populations that might be eating the insects. As they are affected, there’s a whole domino effect through the biosphere.”

It can feel like a bleak picture, but there are solutions. Many cities have begun to plan for the coming risks. Toronto has already begun to adapt to this reality by introducing “cooling centres” during the height of summer heat.

“But it’s not really dealing with the underlying issue,” says Edwards. She believes buildings and infrastructure must be retrofitted to withstand the new climate realities. And public health campaigns must continue to raise awareness of both insect-borne and heat related illnesses.

Some of this work has already been done at the municipal and provincial level, but is it enough? Is adaptation really all we have left?

Research has shown that a rapid reduction in greenhouse gas emissions leading to reduced temperature changes can slow the process in many palpable ways. A 2011 study through McGill University found a link between climate change and the geographical distribution of the mosquito culex pipens, the species that carries the deadly West Nile virus, which has grown steadily in its effects since first appearing in the Western Hemisphere around 1999.

Using climate estimates from the IPCC 4th Assessment Report, researchers found that if emissions were curtailed and there were a quick transition to cleaner, more energy efficient technologies, the spread of this kind of disease-bearing mosquito is significantly reduced. If not, the rise in suitable habitat for the species will increase from 211 per cent to 518 per cent by the 2080s.

That would cover 100 per cent of the Maritime Provinces (excluding Labrador), much of Southern Quebec, Ontario, Manitoba and Saskatchewan, and great swaths of Alberta and British Columbia.

Fluery is not the only researcher to connect the public health risks of climate change to the Walkerton tragedy. Thomas J. Duck, an associate professor in the Department of Earth and Atmospheric Sciences at Dalhousie University, sees the recent cuts to environment Canada’s budget as a reflection of the same kind of neglect and shortsightedness on a much larger scale.

“Since the cuts began in earnest in 2011, scientists have been sounding the alarm,” he wrote in the Toronto Star last month. “Their warnings have fallen on deaf ears. And, as was the case in Ontario, it appears that the federal government has not assessed the risks.”

“Protecting the health and safety of Canadians is a key responsibility of the federal government. Investment in environmental protection — Environment Canada’s job — is only prudent.”

Image Credit: Ramón Portellano via Flickr