The last time the Southern Netherlands were hit by the plague was during the epidemic of 1667-68. Up until that point the disease had descended on the population in successive waves and they were faced with an outbreak every decade or so. It is impossible to tell, however, whether high mortality rates were always caused by the bacteria Yersinia pestis since ‘plague’ was a word that covered a variety of infectious diseases.
For the period preceding the keeping of parish registers, death notices in probate inventories, tax registers and annuities constitute the main sources for gauging the extent of mortality. The most severe outbreak of the plague known as the Black Death devastated the Southern Netherlands from the second half of 1349 onwards with flare-ups until 1351. Europe-wide mortality has been estimated at up to one third of the population.
Some scholars believe that its impact in the Low Countries was not as great because of the better socio-economic conditions here, however, that favourable position has been strongly contested in recent studies.
During the eighteenth century, smallpox took over from the plague as the main cause of death, causing havoc among children in particular. Epidemics at the time tended to be the result of outbreaks of dysentery also called ‘the bloody flux’ because of the bloody diarrhoea accompanying the disease.
A definitive explanation for the disappearance of the plague does not exist, although better rules for quarantine, stronger human immunity, decreasing virulence of the bacterium, or the disappearance of the black rat which spread the disease (probably) via fleas, have been cited as the main reasons.
In contrast, there is no doubt about the reason for the decline in smallpox-related deaths. The discovery of a cowpox vaccine in the late eighteenth century by the English country doctor Jenner, the first vaccine ever, meant the disease could be brought under control in the majority of European countries including Belgium. As a consequence of the Franco-German War, a short but intense flare-up was recorded at the beginning of the 1870s. Today smallpox is the only disease that has been exterminated worldwide.