Stamping out syphilis: can the United States finally vanquish this sexually transmitted disease?

Federal health officials have targeted an age-old enemy: Treponema pallidum, the spiral bacterium that causes syphilis. U.S. health officials have declared war on syphilis before, but this time the battle may be winnable. The Scandinavian countries have already conquered the disease.

In the July 17 Science, Michael E. St. Louis and Judith N. Wasserheit of the Centers for Disease Control and Prevention (CDC) in Atlanta argue that now is the time to eliminate syphilis from the United States. Although the disease has been beaten back to an all-time low of just 3.2 cases per 100,000 people, that statistic doesn't adequately convey the threat that syphilis still poses, the researchers say. Only a decade ago, the number of cases spiked to 20 cases per 100,000 people, and it could rise again.

A recent scientific advance promises to speed up the work on a vaccine. Public health workers, however, do not plan to wait for vaccine development. The currently low incidence of syphilis represents "a small window of opportunity that we cannot [afford to] lose," says Charlie Rabins, chief of the sexually transmitted disease section of the Illinois Department of Public Health in Springfield.

Like a forest fire that continues to smolder in a few isolated areas, syphilis remains a threat in the southeastern United States and some urban areas. CDC officials note that in 1997, just 31 U.S. counties reported more than 50 percent of all syphilis cases. If left unchecked, those pockets of disease could ignite a public health disaster.

"We're sitting on a potentially massive bonfire," St. Louis warns.

In the 1940s and again in the 1960s, public health programs substantially reduced syphilis rates in the United States but failed to eliminate the disease. Untreated, syphilis can lead to fatal heart disease and brain damage. Now, the AIDS epidemic is lending additional urgency to defeating syphilis.

People with sexually transmitted diseases face a greater threat of contracting HIV, the virus that causes AIDS, says Edward W. Hook III, who studies sexually transmitted diseases at the University of Alabama at Birmingham. Infection with T. pallidum causes an ulcerlike sore, called a chancre, on the genitals. Because that wound can serve as a portal of entry or exit for HIV, someone infected with syphilis can more easily contract HIV infection and also readily pass the deadly virus on to another person.

Indeed, researchers have noticed a number of links between syphilis and HIV infection. For example, the outbreak of syphilis in the southeastern United States contributed to the spread of HIV in that region, according to CDC research.

"We now have evidence that HIV transmission, particularly heterosexual HIV transmission across the South and in a few large cities, essentially echoes the syphilis epidemic of the late 1980s and early 1990s," Wasserheit says.

A syphilis outbreak that hit Baltimore in 1995, and continues to spread, also shows deadly ties with HIV. People in inner-city Baltimore who have been diagnosed with syphilis have a one-in-five chance of being infected with HIV, says Jonathan M. Zenilman of Johns Hopkins Medical Institutions in Baltimore. That's about four times the incidence found even in the high-risk group of people treated in clinics for a variety of sexually transmitted diseases, he says.

Aside from the AIDS concern, researchers note that a pregnant woman infected with syphilis can pass the disease to her fetus. During the most recent syphilis epidemic, from 1987 to 1993, 3,000 U.S. infants were born with this disease per year. Babies with syphilis can die from the infection or suffer blindness or lifelong neurological problems, St. Louis says.

At first glance, syphilis seems like an ideal candidate for elimination. The spirochete that causes the disease lives only in humans. The relatively long incubation period means that public health workers have enough time to identify potentially infected sexual partners before symptoms appear and provide them with injections of penicillin or other antibiotics.

Although antibiotics cure the infection, public health experts remain cautious about their chances of abolishing syphilis in the United States. "The most important barriers to eliminating syphilis are not biomedical," Wasserheit says.

To appreciate the difficulty of the task, consider that most people don't even want to talk about syphilis, colloquially known as bad blood or the pox. "As a society, we have a hard time talking frankly and openly about sex," St. Louis says.

Many people in the United States regard syphilis as a moral--not a public health--issue. "There's a tendency to think that those who've acquired a sexually transmitted disease got what they deserved," St. Louis says.

"If you approach this as something that is incontrovertibly wrong, you've really erected barriers to conversation, to risk reduction, and to any sort of educational process," Hook adds.

That problem is compounded by a lack in the United States of physician training about syphilis, says John E Toney, an infectious disease specialist at the University of South Florida College of Medicine in Tampa. Toney says medical schools don't generally put much emphasis on diagnosing sexually transmitted infections. In addition, physicians may be reluctant to bring up the possibility of such infections with patients, he says.

Moreover, policy discussions of syphilis in the United States remain under the shadow cast by the Tuskegee Study. That infamous government project, conducted from 1932 until 1972, withheld treatment from black men afflicted with syphilis in an attempt to research the natural course of the disease.

The Tuskegee study is widely acknowledged today as a model of unethical research. Last year, President Clinton apologized formally for the study, which was supervised and funded by the CDC.

"One result [of the study's unethical protocol] has been the crippling of syphilis research and prevention programs, in part because of shame, distrust, and lack of frank dialogue and leadership," St. Louis and Wasserheit say in their SCENCE article.

Further complicating the task of eliminating syphilis is its ties with poverty. Syphilis flourishes in communities that lack "the financial and social resources to provide people with basic health care," Wasserheit says.

"In our country, unfortunately, that frequently means minority communities," she adds. Syphilis currently affects a disproportionate number of African Americans in the United States. Rates of syphilis are 50 times higher among blacks than among whites.

"The proportion of people living in poverty is greater in the southeastern United States," where syphilis remains most problematic, Hook says.

Drastic reductions in public health funding may also help explain why some areas get hit with an explosion of syphilis.

Consider Baltimore. From 1993 to 1995, the number of syphilis cases there doubled. Public health officials described the outbreak in the March 1, 1996 Morbidity and Mortality Weekly Report. They blamed the epidemic on the escalating use of crack cocaine, the practice of exchanging sex for drugs, and the breakdown of the public health system.

The report notes that the number of city health workers charged with the notification of sex partners of infected people has declined from 14 to 8 during the syphilis epidemic.

An epidemic, like that in Baltimore, of this easily treatable disease is a "sentinel public health event," Wasserheit says. "It means that the system is not functioning adequately."

Indeed, parts of the United States resemble less developed countries when it comes to sexually transmitted diseases. "We have to begin to address the question of why sexually transmitted diseases are 5 to 15 times higher in our nation than in any other developed country on Earth," Hook says. "In Scandinavia, the only way that people get syphilis is by leaving their country," he says.

Hook looked at the scope of sexually transmitted diseases in the United States as part of a committee appointed by the National Academy of Sciences' Institute of Medicine in Washington, D.C. In a 1997 report, that group concluded that an effective national system for preventing sexually transmitted diseases does not exist in the United States. The report estimates the direct and indirect costs associated with sexually transmitted diseases other than HIV infection at about $10 billion a year. It called sexually transmitted diseases "hidden epidemics of tremendous health and economic consequences."

A recent scientific advance may help pave the way toward CDC's goal of syphilis elimination. In July, Claire M. Fraser of the Institute for Genomic Research in Rockville, Md., and her colleagues reported the genetic sequence of T. pallidum (SN: 8/1/98, p. 79). With the blueprint for the molecular secrets of this bacterium in hand, researchers finally may be able to develop a vaccine against syphilis, Wasserheit says.

Scientists have been unable to create a vaccine in large part because they haven't found a way to culture T. pallidum in the laboratory. The spirochete can only be grown in mammals, usually rabbits, which, makes it difficult to study, says St. Louis.

A vaccine for syphilis would go a long way toward stamping out the disease. "Public health disease eradication has never been successful without a vaccine," Hook says.

In addition to facilitating a vaccine, the genetic sequence of T. pallidum may also help medical investigators track a syphilis epidemic, St. Louis notes. Researchers could distinguish, or type, different strains of syphilis and use the information to trace an infection back to its origin. Now, investigators must ask each patient to recall recent sexual partners, a process that is often fraught with poor memory.

"You can almost never connect all the dots in these outbreaks," St. Louis says. With genetic typing, researchers might be able to quickly track an emerging syphilis flare-up, he says.

Public health experts argue that there may never be a better time to launch a strike against syphilis. "In 1997, 85 percent of new syphilis cases were in just 6 percent of counties," says Wasserheit. "That means we can go in in a very targeted way and focus our efforts."

"CDC is demonstrating a level of commitment that hasn't been seen in the past," Hook says. Previously, he notes, funding was cut when the national syphilis rates dropped to low levels, an error that may have led to more outbreaks of this disease.

CDC is vowing to correct the mistakes of the past. The agency has proposed that Congress set aside $25 million per year for 5 years to help with the effort to erase syphilis.

Wasserheit notes that the federal government plays only one part in the campaign to achieve victory over T. pallidum. "At the federal level, we can try to help lead the charge, but the commitment will have to be at the state and local level," she says.

Baltimore is a case in point. "There has to be a serious commitment to looking at public health in this city," Zenilman says. "Eradication is not on the horizon here."

What happens if the move to quash syphilis in the U.S. fails? "The alternative to moving to elimination now is the resurgence of another epidemic of syphilis with its attendant consequences," Wasserheit says. History suggests that without a strong control program, syphilis breaks out every 7 to 10 years, Rabins adds.

"This disease is not going to sit still while we decide whether or not we really want to deliver a good knockout blow," Wasserheit says.