Blacks in the District need to realize that AIDS is not a "white man's disease," Dr. Wayne Greaves, chief of infectious diseases at Howard University Hospital, said yesterday in a news conference aimed at increasing black awareness of the deadly disease.

Of the 252 persons in the District who have been classified as having acquired immune deficiency syndrome since 1981, slightly more than half -- 52 percent -- are black, Greaves said. Nationwide, 25 percent of the 14,288 persons who have been found to have AIDS are black, according to the federal Centers for Disease Control.

Greaves said a disproportionate number of blacks have AIDS, but CDC officials said such a proportional analysis is impossible because there are no figures to show how many members of AIDS risk groups, such as homosexuals and drug users, are black.

Although blacks make up 25 percent of all U.S. AIDS cases but make up only 12 percent of the U.S. population, it is invalid to compare the two figures because risk group members -- not the general population -- commonly contract AIDS, said Dr. Harold Jaffe, director of AIDS epidemiology for the CDC. "No one knows the racial distribution of drug users or gay men," he said.

Greaves noted that the number of AIDS cases among drug abusers in the District is much lower than expected. Only 7 percent of the city's AIDS cases are thought to be caused by intraveneous drug use. Nationwide, the rate is 17 percent, according to the CDC. One reason may be that D.C. drug users appear to share needles less often than those in other cities, Greaves said.

Greaves said the misconception that AIDS does not afflict blacks has caused black community groups to avoid helping AIDS patients. "I try to refer my patients to community services to get help and support and there's only one, the Whitman-Walker Clinic," he said. "Understandably, some blacks have trepidation about going to the clinic," because most of those served at the Adams-Morgan clinic are white.

Caitlin Ryan, director of AIDS education at the clinic, said the facility has trained 348 AIDS volunteers in the last year, 20 percent of whom are black. Two of the six staff members of the AIDS education project are black, she said.

"We have . . . done outreach, but there aren't enough black volunteers," she said. "A problem is that black volunteerism has revolved around the churches and the black churches haven't gotten involved with AIDS."

A problem, she said, is that homosexuality is not accepted readily in the black and Hispanic communities. "Many blacks are closeted," she said. "The sanctions are much higher there."

The clinic has operated a Black-Hispanic Project in the last year, paid for partly by the D.C. Commission of Public Health. With another grant from a private foundation, the Chicago Resource Center, the clinic began last February advertising AIDS programs for blacks and Hispanics on Metro fare cards and on bus posters, an effort that is continuing.

Ryan and Greaves emphasized that more education is needed to prompt blacks to seek medical attention early if they suspect they have AIDS.

But most wait until they are very sick because, "It's more important for a black to work until he absolutely can't than to worry about a lymph node," said Greaves. "There's a general difficulty of access to health care."

At Howard University Hospital, which has treated 20 AIDS patients, Greaves said, there are no formal education projects. The hospital has begun a study of health care workers who care for AIDS patients or who have stuck themselves with needles while handling blood of an AIDS patient, he said.

"We're looking at nurses for five years to see if" their blood shows exposure to the AIDS virus, Greaves said.

There are no reported cases of such exposure among nurses. There are three cases in the United States and one in England of health workers with needlestick injuries whose blood shows exposure to the virus. All denied being a member of a risk group.

Greaves said the evidence is "extremely low" that the Howard study of nurses and health care workers will show exposure.