Medieval manuscripts are "biological time capsules" for deadly sheeppox virus
Sheeppox is a highly contagious, often fatal viral disease that was largely eradicated from much of European livestock in the 20th century.
Other archives and libraries around the world may also contain genetic traces of past disease outbreaks.
Per the authors, the earliest known written evidence of sheeppox infection dates to the first century CE, when Roman accounts described outbreaks of skin lesions (“pustules”) in the animals. There are more frequent mentions of deadly outbreaks of “pockes” or “variola” in sheep by the Middle Ages, recorded in various agricultural texts and accounting documents in France, Spain, and England. There seemed to be a decline in outbreaks in 17th-century France, although frequent outbreaks re-emerged in the 18th and 19th centuries, often with high mortality rates in the flocks. Great Britain did not experience a sheeppox resurgence until 1847.
However, very little was known about the genetic history of the sheeppox virus. That’s why L’Hôte et al. turned to analyzing DNA in medieval manuscripts—the parchments were often made from sheep leather. A number of analytical techniques have emerged in recent decades to help create these kinds of historical molecular records.
For instance, last year we reported on research that used microbial DNA analysis of human remains to identify the likely pathogens that killed many soldiers in Napoleon’s army in 1812. Two pathogens in particular stood out: Salmonella enterica , which causes paratyphoid fever , and Borrelia recurrentis , which is transmitted by body lice and causes relapsing fever . Both are consistent with written contemporary accounts.
