Influenza virus might have marine origin with fish as early host

Influenza virus might have marine origin with fish as early host

Why in news :

  • A new study posted as a preprint in bioRxiv has found that the order Articulavirales, which includes the influenza viruses, first emerged in aquatic ecosystems, and fish might have been the earliest hosts of influenza virus.
  • The study found that invertebrates rather than fish might have likely been among the first hosts of influenza virus.
  • Besides aquatic origin, the researchers say that the order Articulavirales may have persisted since about 640 million years ago when corals branched off to form other members of Articulavirales in other animals.
  • A 2018 identification of a distant relative of influenza in hagfish only strengthened the possibility of a marine origin of the virus.
  • The researchers stress this point about fish serving as the early host to influenza virus in the preprint.
  • The virus in the Articulavirales order “utilises a large repertoire of transmission routes”.

About Influenza :

Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world.

There are 4 types of seasonal influenza viruses, types A, B, C and D. Influenza A and B viruses circulate and cause seasonal epidemics of disease.

  • Influenza A viruses are further classified into subtypes according to the combinations of the hemagglutinin (HA) and the neuraminidase (NA), the proteins on the surface of the virus.
  • Currently circulating in humans are subtype A(H1N1) and A(H3N2) influenza viruses.
  • The A(H1N1) is also written as A(H1N1) pdm09 as it caused the pandemic in 2009 and subsequently replaced the seasonal influenza A(H1N1) virus which had circulated prior to 2009.
  • Only influenza type A viruses are known to have caused pandemics.
  • Influenza B viruses are not classified into subtypes, but can be broken down into lineages.
  • Currently circulating influenza type B viruses belong to either B/Yamagata or B/Victoria lineage.
  • Influenza C virus is detected less frequently and usually causes mild infections, thus does not present public health importance.
  • Influenza D viruses primarily affect cattle and are not known to infect or cause illness in people.

Signs and symptoms :

  • Seasonal influenza is characterized by a sudden onset of fever, cough (usually dry), headache, muscle and joint pain, severe malaise (feeling unwell), sore throat and a runny nose.

  • The cough can be severe and can last 2 or more weeks. Most people recover from fever and other symptoms within a week without requiring medical attention.
  • But influenza can cause severe illness or death especially in people at high risk.

Syllabus : Prelims