
The origins of a deadly virus.
While the virus that causes the flu has been in circulation for centuries, it wasn’t until the 1930s that the world started to get a clearer picture of what it was – a viral illness, not bacterial, as was previously suggested in 1892 by the German scientist Richard Pfeiffer. After noting the absence of bacteria in the throat washing of flu patients, British researchers Wilson Smith, C.H. Andrewes, and P.P. Laidlaw concluded that the influenza virus caused the flu. It has four distinct strains, Influenza A, B, C, and D. Of the four, only A originates from birds but can infect humans as well as a wide variety of animals like pigs and horses. Strains B and C are almost exclusively from humans.
The flu season as we know it today comes from strains A and B. Nevertheless, only the A strain causes global pandemics. It is similar to the coronavirus ravaging the globe for the past two years. Health experts say the flu may have been going around the earth for over 500 hundred years, with pandemics spaced out at an average rate of every 40 years. However, it has been circulating primarily within different bird species before evolving into a strain that could infect humans, the most significant change of which occurred in 1918 and triggered one of the deadliest flu pandemics in human history.