SMALLPOX IN SOUTHEAST ASIACI)

In order to understand the history of smallpox 1n this region, or anywhere else, it is Important to appreciate certain biological features of the disease that affect its behavior in human populations. Smallpox was a specifically human disease; there 1s no animal reservoir, and with trivial exceptions, infection was always acquired from a person suffering from smallpox during the acute stage of the disease. The virus does not persist in the body, and persons who have recovered from an attack are immune for life. The variety of smallpox that occurred in Asia was associated with an overall case fatality rate in unvacdnated subjects of about 25%, but was particularly lethal for infants, the elderly (1f they had not been Infected previously), and pregnant women. Vaccination with a related virus, introduced by Jenner in 1798, provided complete protection for 3-5 years and decreasing protection after that time.