Another 48 cases of AIDS were confirmed in Los Angeles County last month, raising the total number of victims of the deadly ailment in the county to 909. A report by county Health Director Robert Gates said 29 victims of acquired immune deficiency syndrome have died since late April, bringing the total fatalities to 476--or 52% of all confirmed cases. Public health officials are investigating another 98 suspected AIDS cases, the report said. Los Angeles County has reported the third-largest number of AIDS victims in the nation. The New York area has 3,615 cases and San Francisco has 1,249, according to the Centers for Disease Control in Atlanta. The number of new cases listed for May is a slight drop from the 56 confirmed in April.