There are currently more than 750 such areas in the National Wilderness Preservation System comprising over 109 million acres -- roughly 5% of the United States by area. Need a refresher from the other 95%? The Active Times picked 10 wild places in the lower 48 states that are truly wild.
Polio, which struck children disproportionately, could attack the central nervous system and cause muscle deterioration, paralysis and even death. American virologist Jonas Salk, who was born 100 years today on October 28, 1914, developed the worldâs first safe and effective polio vaccine.
Poliomyelitis, often called polio or infantile paralysis, is an infectious disease caused by the poliovirus. Approximately 90% to 95% of infections cause no symptoms.n 2015 wild polio was eliminated in Nigeria. Poliomyelitis has existed for thousands of years, with depictions of the disease in ancient art. The disease was first recognized as a distinct condition by Michael Underwood in 1789 and the virus that causes it was first identified in 1908 by Karl Landsteiner.