Smallpox is the only human disease ever eradicated
Variola virus killed with fever, mouth ulcers, and dented fluid-filled blisters that scarred survivors—and blinded some. The last natural case was diagnosed in October 1977; the World Health Organization certified global eradication in 1980, making smallpox unique among human diseases.
Smallpox was an infectious disease caused by variola, an Orthopoxvirus. Transmission was mainly prolonged face-to-face contact, rarely contaminated objects. Case fatality ran about 30 percent overall, higher in infants. Survivors often carried deep scars; some lost sight. Early evidence reaches Egyptian mummies around 1500 BCE. Eighteenth-century Europe saw roughly 400,000 deaths a year, with about one-third of blindness blamed on the disease. Estimates put up to 300 million deaths in the twentieth century and around 500 million in its last hundred years; as late as 1967, some 15 million cases still occurred yearly.
Variola major was the severe common form; variola minor caused milder disease with historical death rates of 1 percent or less. Ordinary smallpox—at least 90 percent of unvaccinated cases—progressed from macules to papules to opaque pustules embedded like beads in the skin, densest on face and extremities, including palms and soles. Confluent sheets of blisters carried fatality around 62 percent in one series. Modified disease in vaccinated people evolved faster and shallower and was rarely fatal. Malignant flat and hemorrhagic forms were uncommon and usually lethal; hemorrhagic "black pox" involved bleeding under the skin and mucous membranes.
Inoculation appears in China around the 1500s and reached Europe in the early eighteenth century. Edward Jenner introduced the modern vaccine in 1796. WHO intensified elimination efforts in 1967. Antivirals that might have helped arrived only after eradication. The English name "smallpox," used from the sixteenth century, distinguished it from syphilis's "great pox." Rinderpest in animals (eradicated 2011) is the only other infectious disease wiped out. Stored virus and historical scars remain the disease's afterlife—proof a coordinated vaccine campaign can erase a human pathogen.
Source: Smallpox
