A virus is a small infectious agent that replicates only inside the living cells of an organism. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea
https://en.wikipedia.org/wiki/Virus
https://www.mdpi.com/1999-4915/11/3/210
https://www.cdc.gov/
https://www.usgs.gov/
https://www.who.int/