Airs, waters and agues: The historical impact of malaria in England and Denmark

Malaria remains a major cause of death in many tropical areas today and was endemic in marshy areas across Europe before the 20th century. The disease is argued to have caused very high levels of mortality in low-lying coastal areas of England and Scandinavia in the 17th and 18th centuries before gradually waning in incidence due to land drainage and agricultural improvements. However global warming is predicted to extend the range and abundance of mosquito vectors and to promote a resurgence of malaria in temperate regions. Efforts to regenerate wetlands to combat climate change have also aroused scientific and popular concerns that malaria may return in lethal form to northern Europe.
Current perceptions of the historical impact of malaria rest on a small number of influential cases studies of the disease in 17th and 18th century England and in Swedish territories (from 1749). These studies claim that indigenous vivax malaria caused depopulation and debility in marshland communities before the 19th century and were especially lethal to recent arrivals who lacked immunity to malaria. These accounts are however inconsistent with the modern epidemiology of P. vivax (dubbed ‘benign’ malaria), and with systematic evidence of malarial infections in later 19th century Denmark and Sweden that indicate high infection rates but very low mortality.
To resolve this paradox we will use two main approaches. First, this study will map major changes in the geographical extent of wetlands between 1600 and 2000 to identify potentially malarial habitats at different dates, and we will use millions of demographic records for over 4,000 parishes in England and Denmark to test whether malaria contributed to excess death rates under a range of environmental conditions. Then the same datasets will be used to test whether anthropogenic changes in water management (drainage, redirection of tidal flows and land reclamation) were associated with improvements in mortality in the 17th – 19th centuries. The study leverages complementary evidence from England, where we have very rich demographic records from the 16th century onwards, and Denmark, where we have very detailed late-19th century evidence of the distribution and seasonal patterns of malaria but where almost nothing is known of geographical variations in mortality before the 19th century. Denmark introduced compulsory notification of malarial cases in 1862 and clinical descriptions of cases align well with modern diagnoses. These very detailed Danish incidence data have been used to define malarial ‘signatures’ that should identify malaria-related mortality in earlier periods when cause of descriptors are unreliable or absent.
The second approach will interrogate anecdotal sources of evidence that have been deployed sometimes selectively in previous studies to bolster claims that historical wetlands were intrinsically lethal malarial habitats. Crucially, wetlands were highly contested environments and claims about environmental health risks were often mobilised to support major capital projects, to caricature local inhabitants or to mislead outsiders. A systematic and critical comparative analyses will be conducted of historical commentaries from a wide variety of sources and perspectives in order to garner diverse historical perceptions of environmental risk and to assess to what extent these correlate with our demographic and geographical evidence of malarial risk. The project will create two publicly available online atlases that will constitute major new resources for the history of wetlands in England and Denmark and project findings will be widely disseminated to local museums, conservation and environmental organisations and malariologists.

Project details

Social Science

Mar 2024 — Aug 2026

$1.03M

United Kingdom