Cowpox: a re-evaluation of the risks of human cowpox based on new epidemiological information.

Human cowpox is a rare but relatively severe infection of interest because of its links with Edward Jenner and the introduction of smallpox vaccine and, more recently, because of re-evaluation of the epidemiology of the infection. This indicates that cowpox is not enzootic in cattle, relegates the cow to a minor role, and emphasizes the importance of feline cowpox as a source of human infection and of wildlife as virus reservoirs. The evidence available suggests that the virus is of low infectivity for humans and should not become an increasing problem despite the cessation of smallpox vaccination and increasing numbers of immunocompromised individuals.