TRENTON, N.J. ? Urging a major shift in U.S. policy, some health experts are recommending that virtually all Americans be tested routinely for the AIDS virus, much as they are for cancer and other diseases.

Since the early years of the AIDS epidemic in the 1980s, the government has recommended screening only in big cities, where AIDS rates are high, and among members of high-risk groups, such as gay men and drug addicts.

But two large, federally funded studies found that the cost of routinely testing and treating nearly all adults would be outweighed by a reduction in new infections and the opportunity to start patients on drug cocktails early, when they work best.

“Given the availability of effective therapy and preventive measures, it is possible to improve care and perhaps influence the course of the epidemic through widespread, effective and cost-effective screening,” Dr. Samuel A. Bozzette wrote in an editorial accompanying the studies, which appear in today’s New England Journal of Medicine.

A failure to institute such screening at doctors’ offices and clinics would be “a critical disservice” to patients with the AIDS virus and “the future health of the nation,” wrote Bozzette, who is from the University of California at San Diego and the Rand Corp. think tank in Santa Monica, Calif.

Dr. Robert Janssen, director of HIV-AIDS prevention at the Centers for Disease Control and Prevention, said the CDC would re-evaluate its guidelines over the next two years, and will consider the study’s findings as well as the availability of new, rapid HIV tests that produce results in a half-hour instead of the usual week or two.

Who would bear the cost of expanded testing — and the cost of the treatment, which runs to at least $15,000 a year — remains a sticky question amid government cutbacks in health-care funding. However, Janssen said the studies’ findings could lead to some insurers to encourage more testing.

One of the studies, by researchers at Duke and Stanford universities and the Veterans Affairs Palo Alto Health Care System, estimated that routine one-time testing of everyone would cut new infections each year by just over 20 percent, and that every HIV-infected patient identified would gain an average of 1 1/2 years of life.

The other study, by Yale and Harvard researchers, found that testing people every three to five years would be cost-effective for all but the lowest-risk people, such as those who are celibate or are in monogamous heterosexual relationships. And even for those people, one-time testing was found to be cost-effective.

Nurse Scherri Rucker-Graves sets up an HIV test in the exam room of the Atlantic City Health Department's mobile van in Atlantic City, N.J., in this June 16 file photo. Two large studies find that testing all adults once, and testing people in major cities or high-risk groups every three to five years, would be a cost-effective way to reduce new HIV infections by about 20 percent each year and get patients needed help.

Nationwide, about 40,000 new HIV infections occur each year. An estimated 950,000 people are infected with the virus, but about 280,000 of them don’t know it.

CDC guidelines recommend routine tests wherever the prevalence of HIV infection is more than 1 percent — basically, cities and some densely populated suburbs.

“If you need proof of the fact that it’s not working, look at all the people who have slipped through the cracks — 280,000,” said A. David Paltiel of the Yale School of Medicine’s division of health policy, lead author of the second study.

The VA-funded study found that in areas where about 1 in 100 patients has undiagnosed HIV — what the CDC calls high-risk settings — widespread testing would cost about $15,100 for each year of good health gained by people diagnosed with the virus, counting the benefits to their sexual partners.

Even in areas with an undiagnosed HIV infection rate of only 1 in 2,000– the rate in the general population — each healthy year gained by newly diagnosed HIV patients and their partners would still cost less than $50,000. That is the threshold at which health economists generally consider treatments to be cost-effective.