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Current Affairs

Origin of smallpox

Date: 29 July 2020 Tags: Miscellaneous

Issue

A new study carried out by an international team of researchers provides fresh insight into the origins of the disease caused by the Variola virus (VARV), suggesting that the smallpox was in existence as early as during the Viking age in the 8th century CE.

 

Background

The origins of smallpox have always been unclear. Until now, the earliest confirmed case of the disease was found in the mummified remains of a 17th-century Lithuanian child, even though written records suggest that it is much older.

 

Details

  • The researchers screened DNA collected from the skeletal and dental remains of 1867 individuals who lived in Eurasia and America between 31, 630, and 150 years ago, to locate the presence of sequences matching the Variola virus.

  • The Variola virus sequence was recovered from 13 Northern European individuals including 11 dated to 600–1050 CE, overlapping the Viking Age.

  • The study also implies that the virus was circulating among people even earlier, about 1700 years back at the time when the Western Roman Empire declined and people were migrating across Eurasia.

  • These sequences, combined with early written records of VARV epidemics in southern and western Europe, suggest a pan-European presence of smallpox from the late 6th century.

  • The study also suggests that the genetic makeup of the viral strain recovered from the 11 individuals is different from the modern version which was eradicated in 1979.

  • The Viking variant of the virus is part of a previously unknown, and now extinct virus group, or clade. Both the modern smallpox and the ancient variant descended from a common ancestor but diverged 1700 years ago.

  • In the course of evolution, however, the active gene count of the virus is shown to have reduced. This has prompted the researchers to speculate that smallpox became more deadly over time.

  • The pox virus is nowhere close to being related to the coronavirus and hence, the result of the study does not have any impact on the current spread of the pandemic. However, it does provide important information on how a virus may become deadlier over time.

  • The DNA evidence suggests that diseases such as plague and hepatitis B are associated with major prehistoric migrations, something that seems now to be true.

  • Whether migrations brought the diseases to new areas or the emergence of disease triggered people to move is a question that archaeologists, historians and geneticists hope to be able to answer.