Smallpox is an acute contagious disease caused by the smallpox (or variola) virus. There are 2 forms of the disease, variola major (ordinary form) and variola minor (alastrim). In the past smallpox was a very common cause of illness and death (especially in children). In unvaccinated people the mortality rate was about 30%. However, following a worldwide vaccination campaign, coordinated by the World Health Organization smallpox was declared eradicated in 1980.