Polio

This disease is suspected to have been around for thousands of years. It usually spreads through contaminated food and water, and targets the human nervous system, which causes symptoms that usually affect the legs and lead to paralysis. In the United States, outbreaks peaked in 1952, when 57,628 cases were reported throughout the nation. Though there is no cure for this disease, a vaccine was developed in the 1950s that has proved effective for decades. Since this is a disease only carried by humans, widespread vaccinations are expected to remove any traces of the disease in future generations.