224 people are believed to have died so far during Pakistan's heatwave in southern Sindh province (nearly 1,700 people died in a similar heatwave in India last month). Most of the deaths have been in Karachi, with temperatures of 45C (113F) in recent days. The city has seen power cuts caused partly by increased electricity demand for air-conditioning. Many of Pakistan’s victims are elderly people who have been suffering from fever, dehydration and gastric problems. The morgue reports an increased number of bodies being brought in. Hundreds of patients suffering from the heatwave effects are being treated at government hospitals. The body's normal core temperature is 37-38C. If it heats to 39-40C, the brain tells the muscles to slow down and fatigue sets in. At 40-41C, heat exhaustion is likely - and above 41C, the body shuts down. Chemical processes start to be affected, body cells deteriorate and there is a risk of multiple organ failure.