NEW YORK -- For the first time in more than four decades, residents of metropolitan New York have contracted malaria from local mosquitoes, federal health officials said yesterday.

Three of the cases occurred last July in the New York borough of Queens, startling city health officials who this year, for the first time in recent memory, are regularly trapping the insects and testing them for the disease. Two other cases, to be reported today in the New England Journal of Medicine, were seen in New Jersey in 1991.

"The people were very clear that they had never been outside the United States," Dr. John Brook of the New Jersey Health Department said of the cases in his state. "We've been free of malaria in this area since the 1940s. Somehow, malaria had to be brought into this country."

The New York cases, which had not been publicized previously, were confirmed to Newsday by authorities with the New York City Health Department and the federal Centers for Disease Control and Prevention.

Malaria was eradicated from the United States during the 1940s and early 1950s, health officials said. Since then, an average of one case of locally acquired malaria has been reported to the CDC each year nationwide.