In the history of the battle against diseases, there are only two that have been completely eliminated from the wild.
Smallpox had been with us for millennia, but it wasn't until sometime around the 17th century that moderately successful attempts at preventing the disease were practiced in the form of variolation, or inoculation with pus from an infected individual. This practice, though effective, carried significant risks, such as actually causing the disease or infection with some additional disease, like syphilis. Then along came Edward Jenner, who discovered that those infected with cowpox appeared to be immune to the more dangerous smallpox. He developed the first rudimentary vaccine in the late 18th and early 19th centuries. As medical knowledge advanced, the vaccine was refined and improved, reducing (though not eliminating) the risk of adverse effects and improving its effectiveness through booster doses. In 1967,
a worldwide campaign was begun to eliminate the disease from the wild, with the last known wild case of smallpox occurring in Somalia in 1977, making it the first disease eliminated through human efforts.
The second disease that we have managed to eradicate from the wild is
rinderpest, a morbillivirus closely related to human measles virus. Rinderpest was once a scourge of cattle. As with smallpox, innoculation was an early attempt to control the disease. Unlike smallpox, inoculation never really caught on, partially due to lower efficacy. Jenner's successes with vaccination using cowpox led to
unsuccessful attempts to use cowpox to prevent rinderpest. Vaccines using the rinderpest virus were developed in the early 1900s, yet despite the development of effective vaccines, control efforts often took the form of wholesale slaughter of livestock when outbreaks occurred. Regional efforts at eradication of the disease began in the 1920s, but coordinated global efforts wouldn't come about for several decades. Ultimately, widespread vaccination efforts led to the
last confirmed case in 2001 in Kenya. Vaccination continued for several more years, as experts suspected the virus could still be circulating among wild animal populations. In 2011, with no other cases appearing, the World Organization for Animal Health declared the disease eradicated.
We know that in the right circumstances (like when a disease is limited to a single species), and with enough effort, we can eradicate diseases. But what if a disease jumps species?
