Driven by drug use and inner-city poverty, the incidence of syphilis in the United States has soared to epidemic proportions in the past four years and is now at its highest level since 1949, according to federal health officials.

In a study to be released today in the Journal of the American Medical Association, the Centers for Disease Control said the rate of syphilis infection, though it fell among whites, rose by 132 percent among blacks since 1985. For the country as a whole, the rate is up 60 percent.

The incidence in some cities, including the District, Philadelphia and Atlanta, is now similar to that in the poorest parts of the Third World.

The figures show that nationwide there were about 37,000 new cases of syphilis among blacks in 1989, more than double the 16,000 of four years earlier. In the District there were about 600 new cases in 1989, almost triple the number in 1985.

The increase has alarmed health officials because of the close association of syphilis and AIDS. Because both diseases are spread through the same sexual behaviors, the rise in syphilis indicates that people with multiple sexual partners are not practicing "safe sex" and, as a result, are highly susceptible to infection with HIV, the AIDS virus. In addition, genital ulcers caused by syphilis greatly increase the chances of HIV infection from any sexual encounter.

The emerging syphilis epidemic -- on the heels of a recent rise in tuberculosis and amid the continuing acceleration of AIDS among low-income Americans -- also highlights a deepening crisis in the U.S. public health system, which many experts say no longer can contain or effectively treat infectious diseases in the inner city.

"This is a completely curable, treatable disease that we should have eradicated two decades ago," said CDC epidemiologist Robert T. Rolfs, one of three federal researchers who conducted the study. "But we haven't."

"We're not even close to having adequate resources for managing curable sexually transmitted diseases in the 20 biggest cities in the U.S.," said King Holmes, director of the center for AIDS and sexually transmitted diseases at the University of Washington. "We haven't got the facilities and we do not have adequately trained clinicians."

According to public health experts, an effective program of prevention and control of syphilis will cost two to three times the $70 million a year currently spent on the problem by the federal government.

"The Reagan and Bush administrations have cut back on infectious disease control programs for 10 years now, so no one should be surprised that these diseases have skyrocketed," said Rep. Henry A. Waxman (D-Calif.), chairman of the House Energy and Commerce subcommittee on health and the environment. "Since we were too shortsighted to pay for an ounce of prevention, now we have to pay the heavy cost of disease and cure."

Syphilis last reached epidemic proportions in the United States in the 1940s, before the introduction of antibiotics capable of curing the disease. In the 1950s, after a concentrated public health campaign, the infection rate dropped as low as 3 persons per year per 100,000 population. It increased slowly throughout the 1950s, 1960s and 1970s, coming to fluctuate around 11.

In 1985, however, the rate suddenly began surging, reaching 18.4 for the nation as a whole in 1989. Among blacks, however, the rate has reached 122 per 100,000 while among whites the rate has dropped over the last four years to 2.6.

According to epidemiologists, the disease exploded among poor minority groups because of the increased use of cocaine in urban areas, which led to the practice of exchanging drugs for sex, and the breakdown of public programs to quickly treat syphilis victims and trace their sexual partners.

Infection rates for black women have jumped 176 percent over the past four years and 106 percent for black men.

Rates differ widely by region. It is highest in Atlanta -- 206.7 cases per 100,000. In the District, which is second, 158.4 men and women per 100,000 are infected, up 186 percent since 1985.

"We just finished doing a survey {of syphilis} in the Dominican Republic," said Thomas Quinn, an epidemiologist at the National Institutes of Health. "Similar studies have also been done in Nairobi and Jakarta. There you find incidences of 100 to 200 per 100,000. Washington, D.C., is smack in the middle."

Quinn said, however, that rates of other sexually transmitted diseases -- such as gonorrhea and chancroid -- remained much higher in the Third World than in the United States.