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.
Jonas Edward Salk (/sÉËlk/ ; October 28, 1914 â June 23, 1995) was an American medical researcher and virologist. He discovered and developed the first successful polio vaccine.n October 20, 1998, after 18 years of using the Sabin vaccine, however, the federal government recommended that children use the Salk vaccine exclusively. Sabin's polio vaccine is no longer available in the United States.