Four photographs showing patients suffering from smallpox, including one from Montana and one of a baby.

Over thousands of years, smallpox killed hundreds of millions of people, making it known as one of the deadliest diseases known to humans. It is also one of the only human diseases to have been eradicated, declared so in 1980, a significant achievement realized through childhood immunization programs and targeted surveillance and containment strategies. Smallpox was deadly and gruesome. Symptoms included high fever, vomiting, and mouth sores, followed by fluid-filled lesions on the whole body. Death would come suddenly, often within two weeks, and survivors

could be left with permanent scars, such as blindness and infertility.