The bed nets and insecticide products keep mosquitos from biting people while they sleep. Malaria is caused by small organisms carried by the mosquito. Over time, these parasites have begun to develop resistance to some anti-malarial drugs.

Professor Greenwood says he has seen this in Cambodia, and thinks the same thing is happening in other Southeast Asian countries.

“Fortunately, not yet in Africa. But it would be a disaster if those parasites got loose in Africa, and our main treatment was failing again, like it did with chloroquin.”

Researchers say it is important for donors to continue to provide money for treatment. At this time, there is no drug that can keep people from becoming infected.

Finally, a new study has added to evidence suggesting that being bilingual is good for the brain. In the study, older adults who have spoken two languages since childhood showed better mental skills than those who speak just one language.

Earlier studies showed that bilingualism seemed to favor the development of these heightened skills. Organizers of the new study say their findings provide evidence of that cognitive advantage among older, bilingual adults.

In the study, the researchers asked people to sort colors and shapes in a series of simple exercises. They used brain imaging to compare how well three groups of people switched among these exercises. The groups were bilingual seniors, monolingual seniors and younger adults.