THE UNITED STATES has stumbled into its first preventable epidemic, a wave of tuberculosis with strains so virulent they threaten to return pockets of American society to a time when antibiotics were unknown.

The resurgence has been swift, forceful and for many of America's largest cities, it has come after two decades of searing budget cuts in public-health programs. Without those cuts, experts say, the disease could have been all but eradicated, and new, deadly strains would never have been able to flourish.

The last time New York City had 4,000 cases of TB–in 1967– more than 1,000 beds in municipal hospitals were specifically assigned for tuberculosis patients. Today there are fewer than 75. There were 22 full-time chest clinics in the city in 1968; today there are 9. And each of those that remain is so overcrowded and dilapidated that scores of patients must huddle each day in the drab, dimly lighted corridors as they await treatment.

'Close the Book'

Little more than 20 years have passed since a Surgeon General traveled to Capitol Hill and stated with confidence that it was "time to close the book on infectious disease." For most of America, the claims seemed justified. Typhoid, cholera, even measles — major killers not long ago — had largely passed into memory. And cases of tuberculosis, the withering scourge that infiltrates the lungs and slowly, painfully shuts them down, had declined for more than half a century.

But, kindled by the AIDS epidemic, and fueled powerfully by urban crowding, homelessness, immigration, drug abuse and the rapid disappearance of preventive-medicine health clinics in cities from New York to Los Angeles, TB has surged again in a society that had assumed it was gone for good.

"I'm scared," said Dr. Lee B. Reichman, who has just become president of the American Lung Association and who for 30 years has been one of the nation's leading tuberculosis experts. "Here we are in 1992 with cure rates lower than countries like Malawi and Nicaragua. We can't keep track of our patients, and all evidence suggests more and more of them have TB that is resistant to our best drugs. We have turned a disease that was completely preventable and curable into one that is neither. We should be ashamed."

Stark as it is, his assessment reflects the prevailing view among public-health officials. And like many of his colleagues, he blames neglect for the stunning reversal. For while most Americans put TB out of their minds over the last 30 years, it never really went anywhere. In the poorest parts of Miami, Atlanta, Houston and New York City tuberculosis persisted, through the 1960's, 70's and 80's.

In 1970, for example, TB case rates in central Harlem were nearly 20 times the national average, and at least five times higher than the average for New York City. If anything, the disparities have grown worse since then. Last year, reported-case rates in central Harlem soared to 220 per 100,000 residents, among the highest of any American community — and 35 times the figure for residents of the Upper East Side, just a short subway ride away.

Beginning in 1953, when the Government began keeping TB statistics, the number of cases declined steadily from a high that year of 84,300 to a low of 22,000 in 1985. By last year, however, there were nearly 27,000 new cases reported in the United States. The American Lung Association now estimates that without major efforts, the United States will see at least 50,000 new cases every year within a decade and that they will cost the country billions of dollars a year to treat.

Nothing reflects the scope of the epidemic as dramatically as the rise of cases among children, experts say, because each represents a recent infection, not an old one that has returned. Cases among children have more than doubled in New York City over the last two years and have grown by 40 percent across the nation — postponing by many decades the day when TB could possibly be eliminated in the United States.

For years — decades, really — the few experts left to deal with TB in the United States warned that neglect would guarantee a new epidemic. Nobody listened. When numbers started to inch up again more than a decade ago, those experts began to shout more loudly.

Yet, every year between 1981 and 1987 the Reagan Administration opposed the existence of a Federal TB program, calling in each new budget for its repeal. In 1988, increased funds finally began to trickle in, but much of the money was simply diverted from essential AIDS programs.

Federal health officials stress that it would have been impossible to anticipate the devastating effects of the AIDS epidemic, which has sucked resources — the finest minds in science as well as money — from virtually all other areas of medical research. They also note that funds for public-health services have traditionally come from states and cities, not from Washington.

The Disease: A Hacking Cough, A Racked Body

Tuberculosis is particularly insidious. The sufferer becomes enervated, gripped by night sweats, fatigue and the punishing cough that for centuries has stood as the disease's defining symbol.

Not nearly as easily communicable as the flu or the common cold, tuberculosis is spread in tiny droplets through the air. It moves with grim efficiency in places like poorly ventilated homeless shelters, overcrowded clinic waiting rooms and prisons. The TB bacteria has even found an easy home in hospitals, many of which have been designed in the last 30 years without a thought to TB control.

Tuberculosis remains primarily a disease of the poor. It occurs 14 times more frequently among blacks than whites, and much more often in the nation's largest cities than anywhere else. People with H.I.V. are particularly vulnerable. As many as 40 percent of AIDS patients have active TB, and it is those patients who are most at risk from the disease. Their ravaged immune systems leave them far more likely to become infected, and they get sicker much more quickly.

With proper medical care and drug treatment, the illness is readily cured. But the proportion of patients with strains of tuberculosis that resist treatment with conventional drugs has more than doubled in the last decade. Nearly 25 percent of all TB patients in New York City, for example, had clear cases of drug resistance last year. Such resistance develops when patients don't complete therapy, permitting the most resilient strains of the bacteria to thrive. But increasingly, people are infected with these new strains from the start.

For these patients, tuberculosis is a particular horror. Treatment can take years and involve regimens of drugs that are as brutal to the system as cancer chemotherapy. Often part or all of a lung has to be removed. And it can be lonely. Infectious and potentially life threatening, such patients must live virtually isolated from human contact.

The fear of contagion has cast a special pall over a health-care industry filled with workers on all levels who must mingle with the patients every day. There is growing concern that the new epidemic will drive thousands away from the profession.

As the disease spreads, so have concerns over what to do with the small group of patients — usually drug addicts or the mentally ill — who refuse to take their medicine. For the first time in decades, public-health officials have been forced to draft new laws that permit them to lock away patients who are a danger to themselves and to those around them, raising troubling questions about the balance between civil liberties and the public safety.

The Cost :An Opportunity That Was Missed

Gloomy as they are, numbers tell only a bit about TB's re-emergence. It has become clear that the story of tuberculosis in 1992 is also the story of frightening gaps in the world's most advanced health-care system.

Because, as health officials on every level from Washington to Washington Heights readily concede, a disease that will now cost billions of dollars simply to hold in check over the next decade could have been all but eradicated years ago for the smallest fraction of that cost.

"By the 1970's we had pretty much abandoned research efforts in this country," said Dr. Dixie E. Snyder, who for 30 years ran the TB program at the Centers for Disease Control. "We had no real budget. We had to beg, borrow and steal every dollar we could get. We had to get state and local hospitals to do studies for us because we had no funds. By the time we arrived in the 80's, with a problem nobody could ignore, it was clear we were in danger of losing the ability to handle this disease."

Federal-budget requests tell the tale as well as anything else. Only five years ago, Dr. James O. Mason, then chief of the C.D.C. and now Assistant Secretary for Health, testified before Congress that it would cost $36 million a year to wipe out TB in the U.S. by the year 2010. This year the C.D.C. released a new national proposal to combat the deadly surge in tuberculosis. That plan calls for spending more than 15 times the figure Dr. Mason sought in 1987: $540 million a year. And nobody even pretends the job can be done by the turn of the century.

Federal health-policy experts say that they were well on their way to containing TB. Then AIDS came along. The powerful new plague absorbed the complete attention of the scientific establishment and billions of dollars. In 1985, the emerging problem of tuberculosis seemed minute by comparison.

Slow Increase in Funds

"In the past 10 years we have been confronted with a horrendous new epidemic of AIDS," said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases. "And it happened in an excruciating period of constraints on our resources. We have had to make unbearably difficult choices in these years."

Still, only a small percentage of the requested Federal funds have been made available, and this is the first budget cycle in which the Bush Administration has proposed a significant increase in TB funds at all, seeking $35 million for the 1993 fiscal year, up from the $12.3 million it requested in 1992. The House has already approved $74.3 million, nearly twice as much as the White House requested.

New York City, by comparison, will spend at least $100 million in city tax revenues on TB programs this year — significantly more money than the entire Federal effort.

"It is hard not to be bitter about a catastrophe that simply should never have happened," said Dr. Barry R. Bloom, a senior researcher at the Albert Einstein College of Medicine and a TB specialist. "We had everything we needed. All the knowledge, the skills, the medical expertise necessary to eliminate this disease. Instead, this country chose to very nearly eliminate the health-care programs people with this disease need most."

Defenses: Neglected System Is Overburdened

Ironically, scientific achievement itself has helped to create the conditions that have brought America to the precipice of an uncontrollable new epidemic.

Just as psychiatric hospitals closed by the score when powerful psychotropic drugs became available, with one result that tens of thousands of patients no longer had a place to live, TB hospitals quickly became relics when effective drugs were developed to kill the bacterium.

It has been exactly a century since New York City created the nation's first TB-control program. For most of that time, patients were sequestered in sanitariums to stem the spread of tuberculosis. By the 1950's, however, new drugs made it possible to begin shutting down sanitariums in the United States. Patients could take their medicine at home, go back to work and lead normal lives. In America, if not in the rest of the world, TB had ceased to be the defining illness of dread.

The changes have been swift. Inside New York City's aging network of health clinics, patients, if they are lucky, can grab one of the standard-issue orange or green plastic chairs and sit for hours until a harried, overworked doctor can see them. The city is scurrying mightily to expand and refurbish its clinics, but patients and doctors face such consistent squalor that they often find it hard to hide their contempt.

'Worst Possible Place'

"This guy here is sick and infectious," said Dr. Karen Brudney, director of the Bronx TB-control program, as she strode through the Morrisania Chest Clinic, looking for a particular man she had wanted to see. "He walked 30 blocks to the clinic today because he didn't have a subway token. He shouldn't be here. It is the worst possible place for him — and for everyone around him."

Quickly, she gave him a new week's worth of medicine, a subway token and sent him home. But he was one in a seemingly endless stream of poor people to appear that day. None had insurance, and few spoke English.

"Her kids have it now," said Dr. Brudney, pointing to a frail Dominican woman with a lightning bolt tattooed on her arm. "I doubt they have seen a doctor twice in their lives."

Stemming the tide won't be easy. Here again, the past offers few encouraging lessons.

In 1979, Federal officials turned $75,000 over to New York City to test a new idea: a program in which health-care workers would venture into the community and watch people take their medicine every day. Persuading patients to swallow up to a dozen pills a day is never easy, and without unusual efforts it rarely succeeds. New York City's test program was considered the safest, cheapest and most realistic way to stop TB from spreading. And it worked like magic: almost 95 percent of the patients finished their therapy and were cured.

Then the funds disappeared, and the program atrophied, only to be revived last year at a cost in New York City alone of $6 million a year.

The Lesson: Left Unfought, A Deadlier Illness

If anything shows the dangers of neglecting prevention, which is always the cheapest and most effective treatment, it has been the American experience with tuberculosis.

It is easy to see why.

For every $1 spent on preventing TB, for instance, the United States saves from $5 to $10 in treatment costs.

Enough medicine to cure a patient of a simple, uncomplicated case of TB costs $300. With drug-resistant strains those costs rise to more than $6,000. The entire medical bill for a simple TB case, including the price of drugs, supervised therapy and medical exams, averages about $11,000, according to the C.D.C. But treating TB resistant to two or more drugs usually exceeds $250,000.

The unwelcome expenses have sent ripples of anguish through a public-health system already reeling from fiscal contraction. Increasingly, municipal hospitals and emergency rooms have become the only doctor's office for drug abusers, destitute H.I.V. patients and the growing army of the homeless, virtually all of whom are among the 37 million Americans with no health insurance.

Even the skills and expertise needed to fight the TB epidemic have largely been shunted to other fields, delaying any more effective treatment, cures or diagnostic tests. There are few researchers to combat emerging strains of TB, few to understand its complicated epidemiology and fewer still working on a vaccine to stop it completely.

"Every case of drug-resistant tuberculosis is an example of a system that broke down somewhere," said Dr. Margaret A. Hamburg, the city's Health Commissioner. "It means treatment wasn't completed or wasn't delivered properly in the first place. For any single person it's a real tragedy. For a city like New York, if drug resistance is not curbed we could quickly find ourselves back in a world before modern medications were available."