New Research on Smallpox About its Origins

• 28 Jul 2020

Why in News

Recently, a new study carried out by an international team of researchers provides fresh insight into the origins of the Smallpox disease.

• It suggested that the smallpox was in existence as early as during the Viking age in the 8^th century CE.
• The Viking Age was the period during the Middle Ages when the Norsemen (name given to the Scandinavian Vikings) undertook colonizing, conquest and trading throughout Europe, and reached North America in the 9^th and 10^th century.

Smallpox

• About: Smallpox is a contagious disease, caused by the Variola Virus (VARV).
• Transmission: It transmits through the droplets released from coughing, sneezing, and face to face contact with an infected person.
• Eradication: One of the deadliest diseases known to mankind, it is also the only one to have been eradicated by vaccination.
  
  • In 1980, this was declared as completely eradicated after the global immunization campaign led by the World Health Organization (WHO) with the help of the smallpox vaccine.
• Vaccine: The first effective vaccine was discovered by Edward Jenner in 1796.

Key Points

• Origin: 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 17^th century Lithuanian child, even though written records suggest that it is much older.
• Major Findings:
  
  • Finding Virus Sequence: The Variola virus sequence was recovered from 13 Northern European individuals including 11 dated to 600–1050 CE, overlapping the Viking Age.
  • Pan European Presence: 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 6^th century.
    
    • According to the study, 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.
  • Genetic Makeup: It 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 1979-80. 
    
    • 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.
  • Course of Evolution: It was suggested as a benign disease (less dangerous) considering that smallpox may have in the past been a mild.
    
    • In the course of evolution, the active gene count of the virus is shown to have reduced due to mutation.
    • Therefore, the researchers speculated that smallpox became more deadly over time.
• Implications of the New Research:
  
  • Information about the Viruses: The results of the study does not have any impact on the current spread of the Covid-19 pandemic. However, it does provide important information on how a virus may become deadlier over time.
  • Trace of History: Nonetheless, it is important to note that smallpox is the latest among several other diseases whose history in recent years have been rewritten by ancient DNA analysis.
    
    • Earlier, In 2015, a study noted that the plague that killed millions in medieval Europe can be traced as far back as the Bronze age between 3000 and 1000 BCE.
    • In 2018, on the other hand, Hepatitis B was seen to have origins in the Bronze age as well.
  • Ways of Spread: These findings would help to understand the ways in which diseases have affected human populations in the past.
    
    • 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 of variola too.
    • It would also help to seek answers of whether migrations brought the diseases to new areas or the emergence of disease triggered people to move.

Source: IE