Cowpox is a skin disease caused by a virus known as the Cowpox virus. The pox is related to the vaccinia virus and got its name from the distribution of the disease when dairymaids touched the udders of infected cows. The ailment manifests itself in the form of red blisters and is transmitted by touch from infected animals to humans. Cowpox is similar to but much milder than the highly contagious and sometimes deadly smallpox disease. It resembles mild smallpox, and was the basis of the first smallpox vaccines. When the patient recovers from cowpox, the person is immune to smallpox. The cowpox virus was used to perform the first successful vaccination against a disease, smallpox, which is caused by the related Variola virus. Therefore, the word 'vaccination' first used by Edward Jenner (an English physician) in 1796 has the Latin root vaccinus meaning of or from cows.
Contributions by 188.8.131.52, Joelmills, and Justin B Slone.