Measles have increased in incidence in some parts of the developed world in the past 10-15 years. They can be fatal and lead to severe sequelae.Measles were infrequently introduced to Iceland in the 19th century and consequently, epidemics were few but associated with an extremely high mortality. The availability of 19th century church registries enables studies on the impact of measles on mortality.
Historical accounts mention two major measles epidemics, starting mid-year 1846 and 1882. We analysed these two epidemics using contemporary historical sources, mainly original church registries.
In the 1846 epidemic the data show a clear increase in mortality in June and reach a peak in July of 741 fatal cases total, a four-fold increase from expected baseline rate. The epidemic subsided in the ensuing five months. A cluster of measles was described in the eastern region of Iceland in 1869 but did not spread further. The epidemic of 1882 reached its peak in July, when 1084 individuals died, a five-fold increase from the expected rate. Excess mortality was highest in N-Isafjardarsysla county, 4,7 %, and none in A-Skaftafellssysla county where the illness was described 13 years previously. The highest numbers of fatal cases in the 1882 epidemic (64,6%) was among 0-4 year old children. The number of fatalities among women of child-bearing age was more than two-fold compared to men; the number of births 7-9 months following the 1882 peak dropped significantly by 50%.
This study highlights the consequences of measles following introduction into a largely susceptible population and also documents the importance of herd immunity. Information can be identified on most individual fatalities during the 1846 and 1882 measles epidemics in Iceland.