http://poliotoday.org/?page_id=13 Salk Institute http://poliotoday.org/?page_id=13 Salk Institute Polio history http://poliotoday.org/?page_id=13 http://poliotoday.org/?page_id=13 http://poliotoday.org/?page_id=13 http://poliotoday.org/?page_id=13 Salk Institute experienced an epidemic Polio history Polio history Polio history Salk Institute