A zoonosis or zoonotic disease is a microbial infection (virus, bacterium, parasite, fungus or infectious protein) present in animals and transmitted to humans. Zoonoses include infectious diseases transmitted by mosquitoes and ticks such as West Nile virus, Zika and Lyme disease, certain digestive infections such as salmonella and E. coli, and other diseases such as rabies transmitted by an animal bite. Zoonotic diseases are estimated to make up about 75% of emerging human diseases, and many are of a significant epidemic and pandemic nature. Many zoonotic diseases originate from viruses usually present only in animals. Mutations in nucleic acids (DNA or RNA) would change the characteristics of these viruses, making them suddenly infectious to humans. Coronaviruses are a large family of viruses found in animals. Several types of coronaviruses are infectious in humans, causing, among other things, most seasonal colds. Some coronaviruses such as MERS CoV, SARS CoV-1 and SARS CoV-2 (COVID-19) are responsible for severe respiratory diseases. The SARS-CoV-2 pandemic is a particularly deadly zoonosis.