Khaksar’s family knew something was wrong when his fever didn’t break.
The 12-month-old wailed uncontrollably, tears streaming from his big brown eyes. His father visited a doctor in their lush, battle-scarred valley in eastern Afghanistan. But the pills he brought home did nothing.
After a week, the family bundled Khaksar into a taxi and rode for an hour and a half to the small hospital in Asadabad. Tests showed the boy had contracted a disease that is a relic of a past era: polio.
The narrow Sheltan valley, a haven for the Taliban and other insurgents along the border with Pakistan, is also one of the world’s last redoubts for the crippling...