Understanding Malaria Trends in the UK

What is the purpose of archaeology? I get this question a lot. The public often wonders about the value of archaeological studies, other than the intrinsic value of filling in the blank pages of the past. However, paleopathology is a sub-field of archaeology which clearly shows the benefits of doing these types of studies. In the last decade, malaria in Europe and the UK has risen (potentially due to global warming). Understanding the impact of malaria in the present requires knowing the history of the disease in the area. Malaria tends to be classified as a recent disease. This is due to the fact that malaria isn’t found on skeletal remains, and written records regarding the disease don’t appear until the last few centuries. In order to discover malaria trends in the past, we need to come up with alternate methods. A new study by Gowland and Western (2012) traces the presence of malaria in England by using spatial epidemiology to analyze the prevalence of skeletal indi- cators of poor health.

Female Mosquito, Claude Moore Health Science Library, University of Virginia.

Historians argue that malaria has been present in the UK since the Roman occupation began in the 1st century CE. However, it’s also been suggested that it  wasn’t endemic to the region until the post-medieval period due to a lack of evidence. In the 15th century CE, there are records of an ‘ague’ of intermittent fevers occurring widespread across the population, but it isn’t completely clear whether this represents malaria. The word ‘malaria’ wasn’t used to describe a disease until the 19th century CE. Simply because there was no word describing it doesn’t mean that it didn’t exist. Malaria doesn’t leave clear marks on the skeleton like the syphilis or tuberculosis, however it does cause anemia which can cause cribra orbitalia (sieve like lesions occurring above the orbits in the skull). While this could also be used as an indicator of many other diseases or poor nutrition, it is a start for examining trends of malaria.

Gowland and Western (2012) examine a sample of Anglo Saxon (410-1050 CE) skeletons from Eastern England that were recovered from a lowland wetland that would have been a likely location for malaria to be occurring. There study consists of a spatial epidemiological study of skeletal remains in order to determine whether there are correlations between nonspecific skeletal indicators of poor health (cribra orbitalia and enamel hypoplasia), geography, topography, and historically recorded evidence of outbreaks of malaria. They looked at 46 sites that overall had 5,802 individuals, and calculated the prevalence of cribra orbitalia among each sites population. This information was put into a Geographic Information System (GIS), along with environmental data and topography. A survey from the British Museum, dating to 1900 CE, charted the presence of malaria in the continent- this was added to the GIS as well.

Gowland and Western 2012

In order to determine whether there was a relationship between skeletal indicators, the environment, and historic trends of malaria, Gowland and Western (2012) used a function in GIS known as Spatial Autocorrelation (SA). SA measures the “degree of spatial similarity observed among neighboring values”. They found that there is a highly significant correlation between skeletal, indicators of cribra orbitalia, marshy wetlands and historic malaria trends. There was no significant correlation with enamel hypoplasia, meaning general stress or poor health was not the cause of the cribra orbitalia. Another GIS test was done comparing the locations of historically known cases of ‘ague’ and maps of known locations of malaria infected mosquitos done in 1918. Again, there was a positive correlation between the two variables.

Gowland and Western (2012) conclude that there is a spatial relationship between Anglo Saxon cases of high cribra orbitalia and historically recorded malaria cases. It is likely then that malaria did exist, in similar wetland locations, during the 5th century, and potentially earlier. While it may not have been identified as malaria, this doesn’t mean the disease didn’t exist. They conclude that “Spatial epidemiological studies using GIS are not common in palaeopathology, but can be an invaluable tool for integrating historical, geographical, and paleo- pathological variables”. Indeed, this study is able to contradict earlier notions of the recent origins of malaria and is able to trace long term trends of the disease. It also shows a positive relationship between cribra and malaria, and not enamel hypoplasia, meaning that the former is not just caused by general stress. This is a really fascinating study, and hopefully one they will expand to other time periods to continue tracking the trend.

Works Cited
Gowland, R., & Western, A. (2012). Morbidity in the marshes: Using spatial epidemiology to investigate skeletal evidence for malaria in Anglo-Saxon England (AD 410-1050) American Journal of Physical Anthropology, 147 (2), 301-311 DOI: 10.1002/ajpa.21648