Friday, July 31, 1998 Published at 22:47 GMT 23:47 UK
Heat stroke warning
Oklahoma Governor Frank Keating inspects the state's damaged peanut fields
Heat stroke is far more dangerous to health than previously thought, according to new research in America.
The findings are published as much of the southern part of the United States continues to bake in an intense summer heat wave.
The weather has already claimed the lives of more than 150 people and destroyed crops worth hundreds of millions of dollars.
The researchers say the health effects of heat stroke go way beyond the initial episode. Their work is based on the Chicago heat wave of July 1995 which caused more than 600 deaths in nine days.
The study, reported in the Annals of Internal Medicine, followed the progress of patients admitted to intensive care units in the local area.
The researchers found that nearly half of the patients died within a year - 28% after their release from hospital.
Many of the survivors were still suffering from serious health problems one year after the event.
Heat stroke is either "classic", which tends to strike the elderly or infirm during prolonged heat, or "exertional", which usually affects healthy people when they are active in the hot sun.
The study found those with classic heat stroke suffered many of the profound health problems normally associated with the exertional type.
In fact, they were more likely to suffer brain, kidney and cardiovascular damage, previously considered rare in classic cases.
Lead author Maurice Ndukwu from the University of Chicago Medical Centre said the research team were also troubled by the way many of the patients were treated. Very few received the best treatment - immersion in cool or ice water within 30 minutes.
"In this unusual episode, we saw sicker patients with more severe disease than is customary", he said.
"It taught us that classic heat stroke is a deadly disorder, more complex, more often fatal and more permanently disabling than the literature on this order would predict.
"And it drove home the crucial importance of prevention and rapid diagnosis and treatment."