 In Pakistan, doctors are warning of an epidemic of heat stroke as a searing summer heat wave continues to push temperatures as high as 120 degrees Fahrenheit. In Karachi, home to some 15 million people, hospitals have treated thousands of heat stroke victims this week, with one charity reporting 450 people have died in the past four days alone of the heat. Residents say the heat wave has been made far worse by rolling blackouts as an aging electric grid fails to keep up with demand.