BBC says the disease, once thought practically eradicated, is now moving out into China from Pakistan:
Polio has been found in China for the first time since 1999 after spreading from Pakistan, the World Health Organization (WHO) has confirmed.
It said a strain of polio (WPV1) found in China was genetically linked with the type now circulating in Pakistan.
At least seven cases have now been confirmed in China’s western Xinjiang province, which borders Pakistan.