“…the debility of the lower extremities which gradually become more infirm, and after a few weeks are unable to support the body.”

It wasn't until 1840, when German orthopedist, Jakob von Heine, recognized poliomyelitis as a disease on its own, separate from other forms of paralysis. He called the disease infantile spinal paralysis, and would later be termed Heine-Medin's disease until it was labeled as the poliomyelitis we are familiar with today.

Within a year, they published their paper, "The Transmission of Acute Poliomyelitis to Monkeys" (1909), and came to the discovery that this is a strictly human pathogen.

1881: Northern Sweden had 18 documented cases of "poliomyelitis anterior acuta". Epidemics are still small and localized.

1894: First major outbreak in the US in Vermont. 132 cases of permanent paralysis and 18 deaths

1905: The world's most severe outbreak up to that 1905 was located in Sweden. 1031 cases were reported and Sweden was the first country to register cases at a national level.

1905: Polio was discovered to be contagious.

1916: New York City polio epidemic infected around 27000 Americans with the disease resulting in around 6000 deaths

Mid 20th Century: Polio was worldwide and would kill or paralyze over half-a-million people every year

"the relative capacity of a pathogen (such as a bacterium or virus) to overcome a host's defenses and cause disease or damage ; the degree of pathogenicity of a causative agent of disease"

Harm can be described as damage or injury, or a reduction in host's fitness".

Virulence is a relative term describing the severity of a disease, and ranges between 0%-100%.

Less than 1% of polio infections result in paralytic poliomyelitis, which occurs when the virus enters the central nervous system and replicates in the motor neurons of the spinal cord, thus injuring and destroying the motor cells which operate skeletal muscle function. The affected muscles lose their ability to move, resulting in a condition called acute flaccid paralysis. In the most severe of these paralysis cases, bulbar polio affects the brain stem, resulting in loss of function of breathing, swallowing, and speaking.

Without respiratory support, this can lead to death. Between 2-10% of people affected by paralytic poliomyelitis die.

The polio vaccine could also be a reason that the virulence of the virus has remained steady, because the virus no longer infects as many host as before, thus lowering the chance for a higher virulence to develop.

"Well, the people, I would say. There is no patent. Could you patent the sun?”

Soon after, the oral polio vaccine (OPV) was tested and used across the world. This vaccine uses a weak live version of the virus, and had an added benefit of its ease of administration.

Retrospectively, cases were seemingly lower for black communities as a result of medical racism and neglect. Black people affected by the disease at the time did not always have access to quality healthcare, and there was a lack of recognition for those cases that were confirmed.

Black activists pressured President Roosevelt and the March of Dimes to address the reality of lack of healthcare to black polio patients, which lead to the opening of Infantile Paralysis Center at Tuskegee Institute in 1941. This was a center for African American patients of polio.

The Infantile Paralysis Center was closed in 1975 and Warm Springs in 1980 as segregation changes had come a long way with improvement and due to a lack of demand for a polio rehabilitation center.