The Disappearance of Malaria from Denmark in the 19th Century: An Unintended Benefit of Agricultural and Social Changes

Mathias Mølbak Ingholt, Mads Linnet Perner, Andreas Nordland, Henrik Breuning-Madsen, Lone Simonsen

Research output: Contribution to conferencePosterResearch


Background. Malaria, presumably caused by p. vivax, was endemic in rural Denmark during the 19th century. However, beginning in the second half of the 19th century, malaria morbidity declined and was gone from surveillance systems by the beginning of the 20th century. We investigate here its epidemiology and the possible effect on malaria of changes in agricultural practices to accommodate heavier machinery.

Methods. To test out hypothesis that extensive farmland drainages that were conducted to improve the soil for farming led to reduction in mosquito breeding grounds. We identified regional annual data on malaria morbidity incidence and computed the percentage land that had been drained during 1860-1920.

Results. Epidemic malaria was characterized by May peaks, low case fatality and highest incidence in the low-lying clay soil areas of Lolland-Falster in Southern Denmark. At the regional level, we found an excellent temporal correlation between patterns in malaria morbidity and the proportion of the agricultural areas that was drained. Other potential factors that might affect malaria – including changes in living conditions, housing and magnitude and types of domestic animals as well as the use of quinine to treat malaria – did not correlate with malaria disappearance.

Conclusion. Our findings of strong correlations suggest that it was drainage that likely led to the disappearance of malaria in the late 19th century in Denmark. This analysis should be repeated in other European countries that had different temporal patterns of drainage and malaria. This connection has been suggested but so far not demonstrated quantitatively, although drainage has more recently been implied in the control of malaria in some 20th century in China and Africa. In an environmental contemporary perspective we speculate that wet area solutions to climatic changes may bring back the disease in the future; certainly the mosquito vector is still present.
Original languageEnglish
Publication date2017
Publication statusPublished - 2017
Externally publishedYes
EventImpact of Environmental Changes on Infectious Diseases - Abdus Salam International Centre for Theoretical Phsysics, Trieste, Italy
Duration: 17 May 201719 May 2017


ConferenceImpact of Environmental Changes on Infectious Diseases
LocationAbdus Salam International Centre for Theoretical Phsysics
OtherEnvironmental changes — the manifestations of which can include loss of biodiversity and habitat, increasing atmospheric temperature, rising sea level, and climatic instability (e.g., longer and more severe periods of drought or rainfall) — are likely to affect the prevalence of various infectious diseases by making conditions more (or less) propitious for the survival of pathogens and their vectors, and by inducing mass movement of human and animal populations.<br/>This conference will discuss the impact of current and predicted future environmental changes on infectious disease dynamics in people, wildlife, and livestock across the globe, and what actions need to be taken.<br/>Topics include<br/>Environment change and infectious disease<br/>Water-borne and food-borne diseases<br/>Impacts of mobility, travel, trade and globalization on infectious diseases<br/>Land use change, including livestock and agricultural changes<br/>Air quality, urbanization, socio-demographic and economic impacts on health<br/>Vector-borne diseases
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