Cowpox

Cowpox is a viral disease that affects cows and other animals. It is caused by an infection with the poxvirus Vaccinia, a member of the Orthopoxvirus family. People can also contract cowpox from contact with infected animal material, making it an occupational hazard for dairy farmers and veterinarians. Its significance is in its role as the first vaccine; Edward Jenner's 1796 study of cowpox in humans led to the development of a vaccine for smallpox, one of the deadliest diseases known to humanity. The vaccine has since been used to eradicate the disease. Cowpox also provides immunity to smallpox in vaccinated people, and is used in the production of vaccines for other diseases.