Viral Effects
Polio enters the human body through the mouth. According to the World Health Organization, the virus quickly replicates in the throat and intestines and then enters the bloodstream. The Smithsonian states that from the bloodstream the polio virus enters the central nervous system, where it multiplies and attacks the motor neuron cells that control the muscles for the trunk, arms and legs as well as for swallowing, respiration and circulation. While the disease is known for paralysis of the victims, only one in 200 patients exhibits permanent paralysis from the virus.
Transmission
Polio remains in the fecal matter of patients for weeks after the disease is contracted. According to the Mayo Clinic, the polio virus enters the environment through the feces of an infected individual, which is why the disease is only prevalent in a few third world countries today. Because the incubation period is seven to 10 days and many people contract the virus without showing any symptoms, polio can quickly reach epidemic proportions.
Eradication
The polio virus responds readily to immunization, and due to the efforts of the World Health Organization's Global Polio Eradication Initiative, the virus survives in only four remaining countries of the world: Pakistan, Afghanistan, Nigeria and India. Reported cases of the virus have dropped to 1997 infections in 2006; the Eradication Initiative immunized more than 400 million children in 2007 in its efforts to eliminate the virus permanently.
