The application of the principles of hygiene in recent decades has virtually eliminated epidemic outbreaks of the most deadly contagious diseases. Historically, however, epidemic diseases in North America were initially spread from European explorers to Aboriginal peoples. Later, the unhealthy conditions of ships which linked the Americas to Europe favoured the development of contagious diseases such as smallpox, typhus, cholera and influenza among their passengers. Ignorance of the causes of these diseases and how they were transmitted helped spread them into port cities. The outbreak of an epidemic almost always coincided with the arrival of a vessel full of sick passengers.

European Contact with Aboriginal Peoples

When Europeans began arriving on the shores of the Americas, the epidemic diseases they brought with them set off one of the largest depopulations in human history. Prior to European arrival, diseases such as smallpox, measles and yellow fever did not exist in these regions of the world. Having never been exposed to these illnesses, Aboriginal peoples did not have the antibodies needed to ward off infection. Using Christopher Columbus’ arrival in the Americas in 1492 as a starting point, Aboriginal populations were drastically reduced by epidemic disease over the course of the next 400 years, as Europeans continued to explore new territory and came into contact with different communities.

Of all the diseases that affected Aboriginal peoples, smallpox was often the worst. While every tribe’s encounter with European disease cannot be catalogued here, two stories serve as notable examples. When travelling the St Lawrence River, Jacques Cartier observed well-established, heavily populated communities at Stadacona, an Iroquoian village located at what is now Québec City. Not long after his arrival, in the winter of 1535, he noted that Iroquoians were dying of an illness he and his own men seemed immune to. Later historians would identify the illness as smallpox. About 70 years later, when Samuel de Champlain explored the same route in 1603, Stadacona was a ghost town.

Another incident speaks to the intentional spread of disease. In 1763, as Odawa chief Obwandiyag (Pontiac) began his resistance movement against British rule, Sir Jeffery Amherst, leader of the British army, suggested to Col. Henry Bouquet that smallpox be introduced via infected blankets given to the First Nations they were fighting. He wrote, “You will do well to try to inoculate the Indians by means of blankets as well as to try every other method that can serve to extirpate this exorable race.” Several historians note there is no evidence that Bouquet or any of his men carried out the act. That same year, however, William Trent, a trader at Fort Pitt (located in present-day Pittsburgh, Pennsylvania) wrote of a meeting with two members of the Delaware Nation, “we gave them two Blankets and a Handkerchief out of the Small Pox Hospital. I hope it will have the desired effect.”

Estimations of the number of Aboriginal peoples in the Western hemisphere at the time of Columbus’ arrival vary widely, and for this reason it is difficult to say exactly how many died of the diseases Europeans introduced. However, some scholars estimate that, by around 1900, Aboriginal populations had declined by upwards of 93 per cent. Though other factors contributed to their depopulation (e.g., war, dispossession), epidemic disease was easily the most devastating.


By the end of the 18th century inoculation against smallpox had become a popular preventive method in Europe. Smallpox inoculation meant smallpox pus was introduced beneath a patient’s skin. Soon after, vaccination (more effective and less dangerous) appeared in North America. Yet, epidemics of smallpox continued to affect the population. Montréal was hit particularly hard. The epidemic of 1885 was especially dramatic; its scale persuaded municipal authorities to make vaccination obligatory, but medical opinion divided into pro- and anti-vaccination camps, with the latter accusing the former of spreading the disease. The population, terrified, refused to be vaccinated. On 18 September 1885 a riot broke out in the city. People tore down pro-vaccination posters and ransacked the home of the official medical vaccinator, city hall, pharmacies and the homes of municipal magistrates. The extent of the catastrophe (it took 3,164 lives, 2,117 of them children) eventually prompted Montréalers to obey the sanitary authorities and the clergy.


Typhus first reached Canada in 1659, but the outbreak of 1746 was notable for its severity. France had sent a large flotilla of warships to Canada to retake Port-Royal in Acadia. Of the 3,150 soldiers aboard, 1,270 died at sea and another 1,130 in Bedford Basin, where they were supposed to rendezvous with an army coming from Québec. The disease hit the Mi'kmaq of the region and more than one-third died.

In 1847, 9,293 immigrants from the British Isles (particularly those of Irish decent) died during the Atlantic crossing, causing the year to be dubbed "the year of the typhus." Another 10,037 died at Grosse- Île, the quarantine station in the St Lawrence River below Québec, or in the hospitals of Québec, Montréal, Kingston and Toronto. Monuments at Cap des Rosiers on the Gaspé coast commemorate those who died at sea.


The Canadian government feared the introduction of cholera by European immigrants, especially in 1831, when Asian cholera was devastating Europe. New regulations forbade the local population to visit ships in port. A sanitation committee was set up early in 1832, quarantine laws were strengthened and Grosse Île was placed under military command. However, one ship was permitted to leave the quarantine station and was responsible for the cholera epidemic in 1832, when some 6,000 people died. Barely two years later the disease struck again, and sporadic outbreaks occurred throughout the century.


While throughout the history of Canada influenza mortality has generally been low, some epidemics occurred during outbreaks of typhus or other diseases. Since the post-First World War outbreak of Spanish influenza, scientific discoveries have rendered infectious diseases less deadly. Recent influenza epidemics, for example, have caused much sickness but few deaths. Health Canada reports that immunizing high-risk persons, such as the elderly and very young, before each influenza season is the most effective measure for reducing influenza-related complications.

Yellow Fever

In 1710, the germs of a disease as yet unknown in Canada, at the time called "the Siamese disease" and today known as yellow fever, arrived in the port of Québec from the West Indies. The vector insect is Stegomya fasciata. This mosquito found the heat and humidity on board ship ideal for its reproduction and infected the vulnerable passengers with the dangerous virus. The sick sailors were taken to Hôtel-Dieu in Québec, where they died — as did six nurses and 12 priests. The epidemic must have claimed many victims, but the exact number is unknown. Once winter came, the insect and its disease both disappeared. There do not seem to have been any other such epidemics in Canada, even if a few sporadic cases occurred in the country's port cities. The Canadian government has on occasion declared quarantine against American ports where the disease has raged.

Baie Saint-Paul Disease

In 1773, a mysterious disease appeared in the Baie Saint-Paul area that spread through neighbouring parishes and finally reached the Montréal region. Its symptoms included buccal (cheek lining) ulcers, pain in the limbs and finally the destruction of the bones of the nose, the palate, the gums and the appearance of swellings on the head, the clavicles and the bones of the limbs. Men, women and children were all afflicted. After some hesitation and discussion, medical opinion decided that this malady, known as the Baie Saint-Paul disease, was a form of syphilis.

See also: Tuberculosis; AIDS.