HONG KONG (Reuters) - Nearly 3 billion people, or two-fifths of the world's population, were at risk of contracting malaria in 2009 and closer study of the mosquito's life cycle is needed to combat the disease, researchers said in two reports. In the first study, scientists mapped out the geographical spread of the Plasmodium vivax -- the most common parasite that causes malaria -- using reported cases of malaria and details on temperature and aridity. "We estimate that the global population at risk of P.

Climatewire: This time, the heat is really on. From Boston to Washington, D.C., temperatures have soared to 100 degrees or more in recent days, stressing electrical grids, scrambling rail transportation and prompting the swift creation of cooling centers for those who lack air conditioning. Central Canada, portions of the Middle East and China are also coping with searing heat.

GENEVA (AP) - For years, the world has been on the brink of wiping out polio, the deadly disease that can paralyze and kill children. At the World Health Organization's annual meeting of health ministers this week, experts are unveiling what they describe as a new strategy to get rid of the feared disease. But others say there is little new and that if this effort fails, there are serious questions about whether to continue the campaign should be raised. Some experts say eradicating polio is impossible and should be abandoned.