BOISE -- Two years ago, when Idaho became the last state in the country to report its first case of AIDS, Dr. Fritz R. Dixon, the state's chief public health officer, made a decision he believed would enable officials here to "corral the virus."

Acquired immune deficiency syndrome, he decided, would be treated like every other communicable disease. With little discussion and virtually no opposition, Dixon instituted sweeping measures: He barred anonymous testing, a practice many public health officials believe is essential to encourage potentially infected persons to be tested. Doctors, hospitals and laboratories would be legally required to report the name and address of anyone who tests positive, information that would be kept in a locked file and on computer. Counselors would be empowered to ask people to voluntarily identify their sexual partners so that they could be contacted by health officials who would urge them to be tested.

"I don't get complicated about it," said Dixon, a plain-spoken pathologist who has spent 24 years in the state's Bureau of Preventive Medicine. "Everytime we don't find somebody with AIDS, that person may infect others and they will die. It's as simple as that. If every state did the same thing as Idaho, there wouldn't be such a problem."

Even though Idaho ranks 45th nationally in the number of cases reported to the federal Centers for Disease Control -- 18 so far -- AIDS is regarded as a serious, imminent threat. In this deeply conservative, rural state far from the epicenters of the epidemic, state officials are attempting to stop AIDS at the border.

Idaho's policies could serve as a model for conservatives who believe the federal government and most states have badly bungled the job of controlling AIDS, a disease that has struck more than 45,000 Americans. Here concerns about civil liberties, ethics and privacy are outweighed by the widespread conviction that the protection of public health demands aggressive measures.

Although health officials in some cities, including San Francisco, do limited contact tracing, as the practice of notifying sex partners is known, many experts regard it and the mandatory reporting of AIDS infection as misguided and possibly harmful.

They believe that Idaho's policies are likely to drive the epidemic underground by discouraging testing, particularly among gay men or intravenous drug users whose behavior is unpopular or illegal. Furthermore, they contend, there is no evidence that testing changes behavior and some evidence that it does not.

"At the moment the disincentives to contact tracing and mandatory reporting far outweigh any positive impact," said Larry Gostin, executive director of the Boston-based American Society of Law and Medicine who teaches at the Harvard School of Public Health. "Our experience with syphilis shows that compulsory measures do not work. None of the evidence points to the fact that testing changes people's behavior. What does work is intensive education and counseling."

Vermont, with 22 cases, ranks just above Idaho nationally but officials there have taken a markedly different approach to combating AIDS. "We think our public health money would be better spent on education than on contact tracing," said Deborah Kutzko, Vermont's AIDS coordinator. "Testing gives a false sense of security and we need to teach everybody how to reduce their risk."

Dixon dismisses such criticism. "With a fatal disease it is even more important that we do more, not less," he said. "If people who support anonymous testing will present me with a list of names of people I can check who'd come in for anonymous testing, I'll consider it."

So far more than 97,000 tests have been administered through the Red Cross and the state health department; because many blood donors have been tested several times, no one knows the precise number of people who have been screened.

State epidemiologist Charles D. Brockopp estimates that 7 percent of Idaho's one million people have been tested. In the course of the testing, about 100 people, most of them gay men, have tested positive. Nine cases of AIDS-related complex, a lesser form of the disease, have been reported in Idaho, which ranks 44th in population.

The state's gay community centered in Boise, Idaho's largest city and capital, is far different from its sophisticated, affluent and politically influential counterparts in San Francisco and Washington. Few homosexuals are open about their life style in this heavily Mormon state where sodomy is outlawed and where homosexuality is regarded not as an alternative life style but as a crime against nature.

Gay men here say that many are avoiding testing or going to surrounding states that don't have mandatory reporting laws.

Others say they give false names or refuse to divulge the identities of sexual partners, although Dixon says most people comply and that officials "almost invariably get the right name. Most people do not lie."

Some who find they are infected move 650 miles to San Francisco for medical treatment and support they say is lacking here. Only one person in Idaho is currently taking AZT, the only drug approved to treat AIDS.

"A lot of people stay away from testing because they don't want to be branded," said Brian Arnzen, a nurse who directs the struggling Idaho AIDS Foundation. "What is there to offer people? If they test positive they risk the loss of their job, confidentiality, privacy, relationships with their family, everything.

"Besides, the idea that a virus can be corralled is ridiculous," he said. "This is a mobile community at the end of the 20th century, not some frontier town in the 1800s."

Idaho's medical and political establishment is determined to do what it considers necessary to stop the spread of the virus.

"There is a high level of concern in this state about what can happen if we don't take appropriate measures," said Don Sower, executive director of the Idaho Medical Association.

In August the medical society recommended that persons who have had sex with anyone from a "high-risk area" including Haiti, New Jersey and the District of Columbia, be tested.

The state legislature, which last year made it a crime to knowingly transmit the virus, has considered bills to bar infected persons from working as food handlers, in day-care centers or from attending school. Another would have required couples to present the results of AIDS tests before being issued a marriage license.

State Rep. Dean Sorenson, House majority caucus leader, plans to sponsor a bill requiring routine testing for hospital patients. Sorenson, a Boise surgeon, said he would refuse to operate on an infected person not in acute pain "because they're just going to die anyway . . . . Why put hospital personnel at risk?"

Corrections officials are testing inmates entering and leaving prison. State police have been issued rubber gloves, a practice some high school coaches say they plan to adopt when dealing with injured athletes. Several of this city's largest employers have sponsored workplace AIDS seminars and state education officials are drafting voluntary AIDS education guidelines.

Despite its stringent measures, Idaho has in some ways been free of the problems that have plagued AIDS sufferers in other states. There have been no breaches of confidentiality and state law prohibits the disclosure of test results for non-public-health purposes. Last spring a 12-year-old boy with AIDS was admitted without incident to public school near Sun Valley.

But there are signs that Idaho's program may not be working. Despite contact tracing and mandatory reporting for syphilis and gonorrhea, policies in effect for decades, rates have continued to increase.

State health department counselors who do AIDS testing and counseling say they are swamped, but not by those who engage in high-risk behavior.

"What we are seeing is very low-risk people coming in for testing," said Barbara Kirschner, a health department nurse in Lewiston, a small university town near the border of Washington and Oregon. "Gays do not come in for testing . . . . One of my concerns is that because it is reportable, people are not electing to be tested."

"We see a lot of the worried well," said Linda Poulsen, a nurse practitioner with the state health department in Boise. Some people are concerned that they may have been exposed to AIDS because they were served by a gay waiter. Others, Poulsen said, "had an affair 10 years ago and feel they'll get AIDS because it's God's punishment."

"I think there's a lot of concern in the community and not just the gay community about the reporting law and contact tracing," she added. Poulsen said she is especially concerned that the message about AIDS is not reaching what she and others believe is this city's large population of married bisexuals.

Although state officials have launched an education program, the gay community has tried for several years to reach its members through the Idaho AIDS Foundation.

Last month during AIDS Awareness Week, Jerry, a former 52-year-old medical technician dying of the disease, and his lover Alan, 25, a cook, were the focus of an unusual panel discussion that attracted about two dozen gay men.

Their openness about Jerry's illness is rare. "Before, people have died and then it's come out that they had AIDS," said Alan, who requested that their last names be omitted. "We decided, hey, there's no lying about this and people need to know."

In 1985, at the beginning of their relationship, they decided to be tested at the health department because, in Alan's words, both had been "very promiscuous." Both learned they were infected.

A month later Jerry became sick. He lost 100 pounds, endured repeated infections, dementia and severe joint pain that required large doses of morphine.

At the time they were tested, Alan said, the state had not begun contact tracing, so he and Jerry tried to notify their partners themselves.

Alan said he managed to contact three men in Boise, all of whom took the test. One discovered he was infected. He didn't know the names of many of his partners, men he said "were passing through town," among them an airline pilot about whom he often wonders.

"Before Jerry I'd never known anybody who had AIDS," said Alan, keeping a watchful eye on Jerry, who lay, wraithlike and unmoving on a chaise longue padded with pillows to ease his pain. "I was fooling myself just like everybody else is around here. I think people in Idaho need to start talking about AIDS rationally because it's here."

Jerry died 10 days later.