The eradication of smallpox.

The key events in the eradication of smallpox worldwide are related. Smallpox virus was spread by droplets, only from the appearance of the rash until scabs form, 4 weeks later. It only infected humans, making it a potential disease for eradication. It had been endemic in populous areas, largely China and India in ancient times, appearing in Europe in the 6th century and in America in 1520. Smallpox vaccination was known as variolation before the modern practice of vaccination with cowpox (Vaccinia) was demonstrated in 1796. Success of the 10 year long world eradication campaign depended on production of heat-stable vaccines and a reusable pronged needle that used little material. The U.S.S.R. suggested the campaign in 1959, but the current campaign began in 1976. The 1st strategy was intensive vaccination, with moderate success. Subsequent strategies involved surveillance and containment, along with improved reporting methods. The concept of an infected village was introduced, and house to house searches were instituted. Victims were put under guard and all villagers were vaccinated. The last case of virulent smallpox occurred in Bangladesh in October 1975, and of mild smallpox in Ethiopia in August 1976. The cost of the entire 10-year global eradication was $83 million for foreign assistance, and about $160 million spent by the individual countries. This is small compared to an estimated $2 billion yearly spent to control smallpox. It is ironic that smallpox became an epidemic pestilence upon the growth of populations, yet it played a major role in preventing population growth until variolation and vaccination became common.