| Malaria on the Rideau
Among the many diseases that ravaged workers during the building of the Rideau Canal, three of the worst were dysentery, small pox and malaria. Malaria, extremely rare today in North America, is a mystery disease to many. It has been suggested by some that malaria was unique to the Rideau, perhaps brought by the soldiers working on the Rideau who had previously been stationed in tropical climates where malaria was rampant. This isn’t true; malaria was in Ontario both before and after the building of the Rideau Canal.
Malaria has been known for centuries, it was first described by early Egyptians in the third millennium B.C. Malaria is a parasite, plasmodium, of which four species are known. The disease is transmitted to humans by a particular type of mosquito (varieties of the Anopheles mosquito that will bite more than once). It was originally thought to be caused by bad air (hence "mal" - "aria" - literally "bad" - "air"), usually blamed on bad smelling air, such as that coming off a swamp or marsh. During the time of construction of the Rideau it was often referred to as "Lake Fever" or "Swamp Fever".
The life cycle of the parasite begins as a sporozoite that is carried by an Anopheles mosquito and injected into a human. The sporozoite heads into the liver and reproduces asexually. There are few symptoms at this time. When sufficient new sporozoites have been produced, they return to the blood stream, penetrating red blood cells. They reproduce asexually again, forming merozoites. Eventually these infected blood cells burst, releasing the merozoites. As this stage continues, more and more blood cells are destroyed, and the classic chills and fever symptoms start to appear in the victim. The cycle at which the chills and fever occurs, usually 48 hours in temperate malaria and 72 hours in tropical malaria represents the cycle in which the merozoites burst out of the red blood cells. It is at this stage that Anopheles mosquitoes can pick up the parasite when taking blood from a host with the disease. Once back in the mosquito, the merozoites develop into male and female gametocytes. These gametocytes fuse in the mosquitoes gut and produce sporozoites, which head into the mosquito's salivary glands, ready to infect another host (human).
The type of mosquito in Eastern Canada and the U.S. that transmits malaria is the Anopheles quadrimaculatus. In the spring it lays eggs singly onto the surface of standing water, usually small ponds and puddles. When the larva hatch and form into mosquitoes they head out to find a suitable meal, preferring large mammals, particularly humans. The mosquito usually searches out a suitable host to feed on in early evening, heading indoors, reaching a peak of feeding activity in late evening and early morning. When feeding on a human that has merozoites in its bloodstream, the cycle starts. Soon this mosquito has sporozoites in its saliva, ready to infect the next human it dines on, and the cycle starts all over.
During the construction of the Rideau Canal, a temperate form of malaria, P. Vivax, was present. This was the form of malaria in southern Ontario and it was present in both Kingston and Perth prior to the building of the Rideau Canal. It has two cycles, the normal short (weeks) malaria cycle and a much longer cycle where it would spend nine months or longer incubating in the liver of a human. This longer cycle allowed it to survive the harsh Canadian winter by staying inside a human until the mosquitoes were out and biting again. P. Vivax has a very low mortality rate (essentially 0%) since it infects far fewer red blood cells than other forms of malaria. One explanation for the 2 to 4% mortality rate on the Rideau is that those who died were either suffering from other illnesses of the day, or had health issues such as dysentery, and that getting infected with P.Vivax was the last straw. An alternate, but perhaps less likely explanation, is that P. falciparum, a more virulent tropical malaria, was also present. P. falciparum, introduced into the U.S. with the African slave trade, doesn’t have the ability to over-winter in Canada, so, if it was present, it must have been re-introduced each year.
Groupings of people, such as in the canal construction camps, certainly helped the spread of the disease, allowing mosquitoes to easily transmit the disease from one worker to another. Many of the construction areas were near clear standing water swamps, ideal egg-laying areas for the mosquito. No one escaped from malaria, everyone from the highest-ranking officer to the wives and children of immigrant labourers all suffered from it. It was most prevalent in the southern Rideau, within the range of the anopheles mosquito. There are no definitive records regarding how many deaths due to malaria occurred during the building of the Rideau Canal. Surviving records indicate an on-site mortality (death) rate of about 2% and a morbidity (sickness) rate of about 60%. Many left the work sites during the “sickly month” (August) so the actual mortality rate may be higher, perhaps up to 4%. One educated guess (Passfield) is that upwards of 500 men (excluding women and children) died as a result of malaria contracted while working on the Rideau Canal.
In the 1820s and 1830s the only known cure, or at least a medicine that could mitigate some of the symptoms, was Quinine. Cinchona bark (containing quinine) had been used since the late 1600s to treat malaria, but it was the isolation of quinoline alkaloid in 1820, named Quinine, that provided a highly potent antimalarial drug. At the time of the building of the Rideau Canal in 1827-31, it was still quite rare and very expensive; it was difficult to obtain in Canada and its use therefore limited.
Long after the building of the Rideau, it was recognized, in the very late 1800s, that mosquitoes, not bad air, were the real cause of the spread of malaria. Even before this was known, malaria was on the decrease. The extensive use of Quinine, the draining of swamps in areas of human habitation, and the use of glass (and later screens) in windows, to prevent the entry of mosquitoes at night, served to dramatically decrease the incidents of malaria. Still, it wasn't until about 1900 that malaria was essentially eradicated from Ontario. It still exists today in North America, although it is quite rare with only a few hundred cases being reported each year, and none within living memory on the Rideau.
For a first hand account of what malaria on the Rideau was like, read the following excerpt from John MacTaggart's book, Three Years In Canada:
Excerpt from "Three Years In Canada"
by John MacTaggart, 1829. Volume II, pages 16 - 21
"Canada has a large, share of disease, like most other countries: it is not so very fine and healthy, as has been reported. There are many hale old people in it, to be sure; but such persons are to be met with even in Batavia, the most sickly town on the earth. If we had no occasion to expose ourselves to the weather, it is probable that we should find ourselves enjoying better health than we commonly do; but who can keep from exposing themselves? We must go forth on our business, whatever that may be. The majority of mankind must struggle to live, in order to die. If we can afford to go out and come in when we please, I dare say there is not any more to be said against sickness in this climate, than in England; but if we have to wander in the wilderness, amongst swamps, as many have-to sleep amongst them, and be obliged to drink bad water - the Dysentery, Fever and Ague, and all manner of bilious fevers, are sure to succeed one another.
The Fever and Ague of Canada are different, I am told, from those of other countries: they generally come on with an attack of bilious fever, dreadful vomiting, pains in the back and loins, general debility, loss of appetite, so that one cannot even take tea, a thing that can be endured by the stomach in England when nothing else can be suffered. After being in this state for eight or ten days, the yellow jaundice is likely to ensue, and then fits of trembling - these come on some time in the afternoon, mostly, with all. For two or three hours before they arrive, we feel so cold that nothing will warm us; the greatest heat that can be applied is perfectly unfelt; the skin gets dry, and then the shaking begins. Our very bones ache, teeth chatter, and the ribs are sore, continuing thus in great agony for about an hour and a half; we then commonly have a vomit, the trembling ends, and a profuse sweat ensues, which lasts for two hours longer. This over, we find the malady has run one of its rounds, and start out of the bed in a feeble state, sometimes unable to stand, and entirely dependent on our friends (if we have any) to lift us on to some seat or other.
This is the most prevalent disorder: sometimes it proves fatal, but not generally so by any means. It leaves, however, dregs of various kinds behind it, which often end in dropsies, consumptions, &c. Those who have had it once will most likely have a touch of it every year. A moist, hot summer fosters it very much; and when we fairly take it, we are rendered useless for any active business for many months. The sulphate of Quinine, a preparation from bark, is what the doctors administer for the cure of this wearisome distemper: it seems to be a very potent medicine, but being very dear, poor people are at a loss to procure it. The Indians are never troubled with any thing of the sort. There is a kind of ague, too, the patient does not shake with, termed the Dumb Ague: this is very difficult to cure, and mostly affects those advanced in years.
The Lake Fever prevails at Kingston, York, and other towns and villages on the borders of the great lakes. It is often fatal, and the nature of it as yet seems not well understood by the faculty.
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In the summer of 1828 the sickness in Upper Canada raged like a plague; all along the banks of the lakes, nothing but languid fevers; and at the Rideau Canal few could work with fever and ague; at Jones Falls and Kingston Mills, no one was able to carry a draught of water to a friend; doctors and all were laid down together. And people take a long time to recover amid these hot swamps; it is not two or three weeks ill, and then up and well again, but so many months. The Ottawa is conceived to be a very healthy river; the people on its banks are seldom or never sick; and the Lower Province is much freer from distemper than the Upper. Stumps in a certain state of decay are said to be dreadfully obnoxious to health."
For more about malaria, you may be interested in reading my article
"Malaria - A Rideau Mythconception"