The Once and Future Canadian Disease

On a February day in Ottawa, the Rideau Canal is teaming with skaters. Along the 7km length of canal, kids and adults alike enjoy some small compensation for the face-burning cold of our long winters. We eat the thick, sugared pancake known as the Beavertail, drink hot chocolate, and feel the ice whip by under our skates.

Canada is just about as far from a tropical
country as it is possible to be, but in the late 1820s, the Scots and French
Canadian Royal engineers who built the Rideau Canal—a 220km canal system
between Kingston and Ottawa—died of one disease more than any other: malaria.

Throughout the 1700s and 1800s, malaria was
endemic to much of the northern shores of the Great Lakes and St. Lawrence
River. 60% of our canal’s builders contracted it every year, and about 4% died
as a result. Tropical malaria brought from the south could not have survived
our winters, which kill off the mosquito vectors long enough to break the
infection cycle. Canada’s malaria, in contrast, is a temperate kind that
hibernates in the liver over the winter only to reemerge in time to meet the
first buzz of a mozzy.

Urban living, quinine treatments, screen
windows, and swamp drainage all played their part in wiping malaria off the
Canadian map, and nobody I’ve talked to in Ottawa is even aware of that part of
our history.

In the past few years, the global progress
on malaria has slowed. There were 219 million cases of malaria in 2017, and 425,000
of those cases were fatal. Almost all of it now happens in sub-Saharan Africa
and India. As a result, the thousands of cases we see in North America every
year are overwhelmingly a result of international travel. But not always.

So-called “autochthonous malaria”, or cases of local transmission, do occur in places with high-quality healthcare. Malaria was declared eradicated in the United States in the 1950s, after a campaign by the CDC’s predecessor. Eradication was defined as three years without a case. But between then and 2003, the United States saw 156 cases of locally-transmitted malaria, including in Northern locales like Virginia, New York, and Michigan.

All you need for malaria is a suitable climate, competent mosquito vectors, and infected humans.  Climate change is working on the first one; we’ve always had the right varieties of mosquito; and new malaria cases arrive on our doorstep every day, usually in the form of our own citizens who failed to take preventative measures abroad. It’s nothing the Canadian health system can’t handle, but it is a little worrying that our memories are so short. As foreign as it sounds to us, malaria is as Canuck as they come.


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