cowpox

cow·pox 'kau̇-.päks n a mild eruptive disease of the cow that is caused by a poxvirus of the genus Orthopoxvirus (species Cowpox virus) and that when communicated to humans protects against smallpox called also variola vaccinia

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n.

a virus infection of cows' udders, transmitted to humans by direct contact, causing very mild symptoms similar to smallpox. An attack confers immunity to smallpox. Medical name: vaccinia.

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cow·pox (kouґpoks) 1. a mild, self-limited, eruptive skin disease of milk cows, principally confined to the udder and teats, caused by a poxvirus; milkers may spread the disease to uninfected animals. 2. human infection with the cowpox virus, as from milking an infected animal; the primary lesions are vesicles that usually appear on the fingers, may rupture and spread to the hands, and heal without scarring. Cowpox is not to be confused with paravaccinia. Cf. vaccinia. Edward Jenner first demonstrated vaccination in 1798 when he showed that inoculation with material from cowpox lesions conferred immunity against smallpox.