Q&A: Polio's History—and Why It's Again Becoming a Threat
Poverty and war have helped spur cross-border outbreaks.
After more than half a century of increasingly successful efforts to eradicate polio, the paralyzing and sometimes fatal disease is staging a comeback and crossing international borders.
This week, the World Health Organization issued a statement calling the spread of the disease from Pakistan, Syria, and Cameroon an "extraordinary event" and a global public-health threat.
Until now, eradicating polio has been one of the most successful worldwide public-health efforts ever undertaken. In 1955, 28,985 Americans—mostly children—were stricken with polio. Then Jonas Salk developed a vaccine in 1955, which was followed by the Sabin oral vaccine in 1963. There hasn't been a case of polio on the United States since 1979.
Since 1988 more than 2.5 billion children have been immunized
