Discovery of the Influenza Virus

  • Medicine & Health
  • 1931

When the influenza pandemic struck in 1918, most scientists and doctors believed it was caused by bacteria. Killing up to 100 million people worldwide, the pandemic was the deadliest in history. This drove many researchers to investigate and study influenza, searching for its cause and cure. A major breakthrough came in the early 1930s, when a young physician from Iowa, Richard Shope, turned his attention to swine influenza. While researching at the Rockefeller Institute for Medical Research, Shope took lung samples from infected Iowa pigs. He was able to isolate the rod-shaped bacterium that seemed always to correlate with their influenza. When the bacterium was injected into other pigs, though, it did not generate disease.

Forced to rethink, Shope referred back to some earlier research by Rockefeller Institute scientists Peter Olitsky and Frederick Gates and used their technique to finally isolate a virus that when injected into healthy hogs caused influenza. The bacterium which coincided with the flu in so many cases turned out to be an opportunistic follower-on which attacked subjects with a secondary infection after the virus had already weakened their defenses.

Shortly after Shope published his swine results, other scientists using his technique isolated the human flu virus. The path was opened to lifesaving flu vaccinations.