NEW YORK (AP) _ Workers on foot began spraying pesticide Saturday in Manhattan in the city's war on mosquito-borne encephalitis that has killed three people.

Six other cases of the potentially deadly virus since Sept. 2 have been confirmed and 89 cases are suspected.

Mayor Rudolph Giuliani urged people not to be alarmed by the increased aerial and ground spraying, expected to continue at least through Monday.

``There are a lot of misconceptions and people are frightened more than they should be,'' he said. ``This is an infinitesimally small amount of people who are affected or will be affected.''

Eight of the confirmed infections were in Queens and one in Brooklyn. All three people who died were at least 58 years old.

Symptoms of St. Louis encephalitis range from a low fever and headaches to a high fever, stiff neck, disorientation and tremors. Because it is a virus, there is no vaccine available to prevent it, but the symptoms can be treated.

City Health Commissioner Neal Cohen says residents should stay indoors for two or three hours after their neighborhoods are sprayed. The pesticide used, malathion, is one of the least toxic pesticides that effectively kills adult mosquitoes, but it can cause eye irritation, rashes and respiratory problems.

The city has set up a Web site and telephone hotline for residents to check on spraying schedules.

Residents also have been advised to wear insect repellent when going outside.