Electronic Thesis and Dissertation Repository


Doctor of Philosophy




Dr. Alain Gagnon


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Few epidemics have been documented in the context of historical Quebec. The rich epidemiological and demographic data contained in the Registre de population du Québec ancien makes it possible to conduct detailed analyses of historical epidemics and can be beneficial to filling in gaps in modern knowledge. The historical studies of measles have a distinct advantage over modern ones, in that epidemics can be analyzed in a natural state unhindered by modern medical treatment and vaccine campaigns. This dissertation attempts to fill this knowledge gap of infectious diseases through the development of methods to analyze epidemics in the absence of cause of death records. The results show the suitability of these methods to investigate the 1714-15 measles epidemic and its impact on the children in the population.

The first study examined the general dynamics of the epidemic that provisioned the baseline for the subsequent studies. Measles entry to the Montreal area was from Colonial America circa late-March of 1714. The epidemic spread eastwards to most other parts of the colony by late-August of the same year and disappeared early in 1715. Measles was virulent with an estimated death rate of 52.8 per thousand for children under age 15. Infants and toddlers were the main victims, while females were slightly more likely than males to have died from the virus. Although the epidemic originated in the Western parishes, severity finally turned out to be higher in the Eastern parishes of the colony.

The second study identified several measles-specific risk factors among children under age 5 were identified with case/control comparisons, which revealed that the effects of these factors were only significant and intensified during the acute phase of the epidemic. Contrary to what was reported in modern studies, singletons or children with fewer siblings had higher odds of dying than children in larger sibships. The age difference between siblings appeared to be a more important predictor of death than the size of the sibship, as a larger average difference led to an increased likelihood of death. As well, children with a sibling who died during the epidemic and children with immigrant parents were at higher risk.

In the third study, exposed children who survived the acute episode of the epidemic were followed for 25 months past the estimated date of infection. It was found that children exposed before age 3 had higher long-term mortality than the unexposed children. The difference remained significant while assessing the effects of the demographic and sibship risk factors. For the exposed cohort, the risk of death also varied by age and sex. Only females exposed during infancy had a significantly higher risk of dying, while both exposed male and female toddlers had higher mortality during the follow-up period. In this case, the effect was slightly stronger for males. No significant long-term mortality difference was found among children exposed between 36 and 59 months of age.