Billionaire Bill Gates said Sunday he would donate $200 million to fund research on Third World diseases, including malaria, tuberculosis, bacterial meningitis, and those related to childhood diarrhea. He plans to spend the funds following a nine-month scientific investigation to identify the world's biggest health problems; the investigation will be led by former National Institutes of Health director Harold Varmus. Gates says the international team will identify about 12 of the world's "grand challenges," which may include looking for ways to block mosquitoes and other insects from spreading viruses and obstructing the replication process of the tuberculosis bacterium. The funding may also go towards researching new ways to prevent or cure AIDS. "It's just a basic fact that 90 percent of the world's health research spending goes on 10 percent of the problems," he said. The $200 million will be disbursed through the Bill & Melinda Gates Foundation for the National Institutes of Health.