Drug abusers are targeted because of key role in spread of the virus. CONTROLLING AIDS

Attention in the struggle against AIDS in the United States is slowly beginning to focus on intravenous drug abusers, such as users of heroin and some kinds of cocaine. The principal reason: IV drug abusers constitute the main bridge over which AIDS and the virus that is judged to cause it can cross into the general American population. ``Our nation's ability to control the course'' of AIDS, warns the President's AIDS commission, ``depends greatly on our ability to control the problem of intravenous drug abuse.''

Experts say that there are promising avenues toward control of AIDS. However, taking them will cost a great deal of money: approximately $1.5 billion a year above current funding just for necessary additional drug-treatment centers, the commission estimates. But drug abusers are ``very difficult to reach,'' warns Dr. Peter Fischinger, director of the national AIDS program office of the US Public Health Service.

Intravenous drug abusers are ``the second-largest group of AIDS sufferers,'' says the National Academy of Sciences in its recent report, and ``the persons most likely to transmit'' the AIDS virus, called HIV, ``to heterosexual partners.''

As a result, says the President's commission, they are ``a major port of entry for the virus into the larger population.'' As the commission notes, ``80 percent of all heterosexually transmitted'' cases of AIDS among native Americans come from IV drug abusers, who contract the virus when they share needles with persons who already have it.

Further, says Dr. Harold Jaffe, the federal government's top epidemiologist on AIDS, ``the major source'' of transmission of AIDS to children is through drug abuse - most frequently from mothers who either use intravenous drugs themselves or whose sexual partners do.

``The situation,'' warns the commission, ``is rapidly worsening as the number of infected drug abusers grows daily.''

Drug abusers are the second-largest group of the 62,000 Americans diagnosed as having AIDS. (The largest group is homosexual and bisexual men.)

The problem is particularly severe among women. Nearly two-thirds of black and Hispanic women with AIDS contracted the illness by sharing needles with drug abusers, according to the US Centers for Disease Control. Almost all of the remaining third became afflicted through heterosexual contact. For many of these women their sexual contact was with drug abusers.

``Drug users,'' says Dr. Alfred Saah, ``that's where we've really got a problem. We're just not reaching drug users.'' In his medical practice Dr. Saah, an associate professor of medicine and public health at Johns Hopkins University, treats people who have AIDS.

The National Institute on Drug Abuse estimates that 1.2 to 1.3 million Americans now are intravenous drug users.

``Former addicts,'' says Dr. Fischinger, ``are probably the only people that intravenous drug abusers'' are willing to believe on the subject of AIDS and the risks of sharing needles.

Many experts feel that the only real solution to changing addict behavior is to end their drug use.

Both the presidential commission and the National Academy of Sciences urge a greatly expanded program to treat intravenous drug abusers: a national policy of ``treatment on demand,'' the commission calls it.

Without a great deal more money, says the academy, such a goal is ``laudable yet distant.'' It notes that three-fourths of the people with drug-related AIDS now live in the New York City area; yet only ``29,400 methadone maintenance treatment slots'' exist ``for an estimated 200,000 IV drug abusers in New York City.''

The commission estimates that the necessary additional treatment facilities and personnel would cost ``approximately $1.5 billion a year'' beyond what now is being spent; it seeks to have the federal and state governments equally share the cost. By economic contrast, it notes, drug abuse costs American society an estimated $60 billion a year.

On the hotly controversial question of whether free, clean needles should be provided to drug addicts in an effort to reduce the spread of AIDS, the academy carefully recommends that ``an evaluation of the effectiveness of providing sterile needles'' to drug abusers ``in certain circumstances is an essential part of planning a prevention strategy.''

Four European nations are experimenting with providing free needles. Results are not yet considered conclusive. A number of major American cities are thinking of starting programs of their own.