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Section 3: Historical Epidemics
Introduction
Contents:
A:
This section uses Bubonic plague in Medieval and early modern European as an example to consider the ways in which epidemics have been important in the past.
But first we need to be reminded why it is necessary to look at epidemics as they occurred in history.
The three main reasons are outlined below:
The first reason is that epidemic diseases were especially important influences on the high level of mortality in the past.
Before the twentieth century it was unusual for life expectancy at birth to exceed 40 years in Western Europe, and for many periods life expectancy was closer to 30 years or even lower. This means that a newly born baby only had a 50/50 chance of surviving to its 30th birthday.
Many died in infancy and childhood, although once a person had managed to live to age 20 then the prospects of survival for a further 30 years were reasonably good.
One of the most important causes of this low life expectancy at birth (high mortality) was the frequent and often devastating outbreak of epidemic disease, such as bubonic plague in Medieval Europe.
The second reason is that historical epidemics allow scientists to study the complete epidemic sequence, that is the original first case through the rising number of cases (and deaths) to the declining curve.
They can also study the frequency of epidemics; how different epidemic diseases interact; how such diseases tend to spread in a wave-like diffusion patter.
Such studies help in the modelling of spread which may enable epidemiologists to judge what is likely to happen should a new epidemic start in the future.
The third reason is that studies of reasonably well documented epidemics which occurred in Europe in the past may help us understand the behaviour of those infectious diseases which are still active in less developed countries today.
Measles seems to be a good example of such a disease, although because HIV/AIDS is a new disease the lessons from historical studies may not be quite so helpful in this case.
