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An international team of researchers have found evidence suggesting leprosy may have spread to Britain from Scandinavia.
The team, led by the University of Leiden, and including researchers from Historic England and the universities of Southampton, Birmingham, Surrey, and Swansea, examined a 1500 year old male skeleton, excavated at Great Chesterford in Essex, England during the 1950s. Radiocarbon dating reveals that he lived between the years AD 415–545.
The bones of the man, probably in his 20s, show changes consistent with leprosy, such as narrowing of the toe bones and damage to the joints, suggesting a very early British case. Modern scientific techniques applied by the researchers have now confirmed the man did suffer from the disease and that he may have come from southern Scandinavia.
Archaeologist Dr Sonia Zakrzewski, of the University of Southampton, explains DNA testing was necessary to get a clear diagnosis: “Not all cases of leprosy can be identified by changes to the skeleton. Some may leave no trace on the bones; others will affect bones in a similar way to other diseases. In these cases the only way to be sure is to use DNA fingerprinting, or other chemical markers characteristic of the leprosy bacillus.”
The researchers tested the skeleton for bacterial DNA and lipid biomarkers to confirm the man had definitely had leprosy and to allow them to carry out a detailed genetic study of the bacteria that caused his illness.
Professor Mike Taylor, a Bioarchaeologist from the University of Surrey, notes that, “Not every excavation yields good quality DNA, but in this case, leprosy DNA isolated from the skeleton was so good it enabled us to identify its strain.”
The results showed the leprosy strain belonged to a lineage (3I) which has previously been found in burials from Medieval Scandinavia and southern Britain, but in this case it originates from a much earlier period, dating from the 5th or 6th centuries AD.
The identification of fatty molecules (lipids) from the leprosy bacteria confirmed the DNA results and also showed it was different from later strains.. Emeritus scientist David Minnikin, from the University of Birmingham, says: “With Leverhulme Trust support, we recorded strong profiles of fatty acid lipid biomarkers that confirmed the presence of leprosy. However, one class of the lipid biomarkers had distinct profiles that may distinguish these older leprosy cases from later Medieval examples.”
Isotopes from the man’s teeth showed that he probably did not come from Britain, but more likely grew up elsewhere in northern Europe, perhaps southern Scandinavia. This matched the results of the DNA, and raises the intriguing possibility that he brought a Scandinavian strain of the leprosy bacterium with him when he migrated to Britain.
Project leader Dr Sarah Inskip of the University of Leiden concludes: “The radiocarbon date confirms this is one of the earliest cases in the UK to have been successfully studied with modern biomolecular methods. This is exciting both for archaeologists and for microbiologists. It helps us understand the spread of disease in the past, and also the evolution of different strains of disease, which might help us fight them in the future. We plan to carry out similar studies on skeletons from different locations to build up a more complete picture of the origins and early spread of this disease.”
Although leprosy is nowadays a tropical disease, in the past it occurred in Europe. Human migrations probably helped spread it, and there are cases in early skeletons from western Europe, particularly from the 7th century AD onward. However the origins of these ancient cases are poorly understood.
The article notes that:
The Great Chesterford case is thus of particular interest in understanding the origins of leprosy in the British Isles, being one of the earliest radiocarbon dated cases with supportive DNA evidence and genotyping of the isolate. The earliest purported example of leprosy from Britain that has been described in the published literature dates from the 3rd-4th century AD and comes from Poundbury, Dorset. This burial comprises lower leg and foot bones only. Although these show changes that are compatible with leprosy, the presence or otherwise of the more firmly diagnostic facial changes could not be ascertained, so the diagnosis is controversial. The first cases of leprosy in Britain showing diagnostic facial signs date from the early Anglo-Saxon period.
The article, ‘Osteological, Biomolecular and Geochemical Examination of an Early Anglo-Saxon Case of Lepromatous Leprosy’ has now been published in the journal Plos One – .