Cholera was a major illness during the 1850's. Cholera is an infection of the small intestine. In 1854 an Italian doctor, Filippo Pacini figured out that there was an actual link between the bacteria of cholera and the disease itself. He discovered this by examining patients with cholera closely with a microscope. With the use of the microscope he was able to see "comma shaped particles", also known as vibrio cholera today, that he linked to causing the illness.
Poliovirus was a dominant illness leading up to and throughout the 1950's. It is an illness that attacks the spinal cord and sometimes the brain. In 1949 David Bodian discovered there are 3 types of the poliovirus (sub-clinical, non-paralytic, paralytic). Vaccines for poliovirus began to come into play in the 1950's. Koprowski tested his vaccine on twenty children and as a result those children developed poliovirus antibodies and did not get poliovirus. The desire to get vaccinated increased tremendously after a polio outbreak in 1952 in the United States. A large portion of the cases during this outbreak resulted in paralysis, which motivated people to get vaccinated.