Smallpox is an acute infectious disease, now eradicated globally. It was characterized by sudden onset with fever, malaise, followed by characteristic skin eruptions which, after passing through stages of macules, papules, vesicules and pustules, dried up leaving scars (pockmarks). Two principle varieties of smallpox were recognized: variola minor (alastrim) and variola major (classical smallpox). In variola major, the fatality rate among unvaccinated was 15 to 40%, while outbreaks of variola minor were associated with a fatality rate of 1%. Although the disease has been eradicated, the virus is still in existence in research laboratories and could conceivably cause an outbreak of the disease in a population no longer protected against it.
Formerly a world-wide disease decimating the human population. The WHO global programme culminated in a world-wide eradication of smallpox. The last known case of naturally acquired variola major occurred in Bangladesh in October 1975. Variola minor persisted in the Horn of Africa until October, 1977. Since that date, two cases occurred in 1978 in Birmingham (UK), related to a research laboratory. Global eradication of smallpox was certified by the WHO in 1979 and confirmed by the World Health Assembly in May 1980. Since smallpox has now been eradicated routine vaccination against smallpox is no longer justified. International certificates of vaccination against smallpox are no longer required by any travellers.
Stocks of the virus are maintained since 1990 by the USA and the USSR. An agreement to destroy stocks, mainly for security reasons, was never effected. The members of the World Health Organization have voted for the destruction of remaining stocks in June 1999. In the meantime, genetic studies of the smallpox virus have encouraged certain scientists to argue for its preservation, as a genetic library from which humans can gain a wealth of knowledge about human disease and resistance to disease.