The first biological weapon, used during the 18th century, smallpox killed 300 million people in the 19th century. There is no specific treatment for smallpox disease, and the only prevention is vaccination. This currently poses a problem, since the vaccine was discontinued in 1970 after the WHO declared smallpox eradicated. Incubation is 7 to 17 days, during which the carrier is not contagious. 30% of people exposed are infected, and it has a 30% mortality rate.