AP Photo

The global battle to wipe out polio has come closer than ever to success, but obstacles remain. The hurdles are not only the highly infectious nature of the disease but also war, corruption, weak public health systems and failing states. Last week added another obstacle to that list: obscene acts of violence. In Pakistan, nine unarmed vaccination workers were killed by gunfire while distributing medicine that could save the lives of countless children. Six of the victims were female, including three teenagers.