Syphilis is making a comeback in the United States. In 2021, total cases of the sexually transmitted disease surged by 27 percent to more than 171,000, and the rate reached a 30-year high, according to preliminary data from the Centers for Disease Control and Prevention.
The spike is part of a concerning trend of rising sexually transmitted infections, but syphilis is particularly worrisome because it can mimic other infections and some people don't even know they have it. Even among doctors, knowledge of the disease is low. Congenital syphilis, which affects babies born to mothers who had the disease while pregnant, is also increasing. Here are answers to some common questions about the disease.
Q: What are the symptoms of syphilis?
A: Syphilis is caused by a bacteria called Treponema pallidum. The early symptoms are one or more concave sores that typically appear in the mouth or genitals about three weeks after sexual contact with an infected person.
"It can be in the back of the throat. It can be inside the vagina. It can be in the rectum," said Jeffrey Klausner, a professor at the University of Southern California and the former director of STD Prevention and Control Services at the San Francisco Department of Health. "People may not be very aware of it at all."
Experts say the sores are typically painless, can last three to six weeks and will disappear without treatment, but that doesn't mean you're in the clear.
A few weeks after the first sores go away, you're still infectious, and a second phase of the infection typically sets in, with a rash on your hands or feet. Other symptoms can include fever, swollen lymph glands, sore throat, headaches, patchy hair loss, muscle aches and fatigue. The rash can also be so faint you don't notice it.
If a person is never treated, they could experience a third phase weeks or years after contracting the disease, which can damage organs, leading to neurological problems, heart issues, loss of sight and death. At this point, the disease is no longer infectious.
Klausner said doctors can sometimes misdiagnose syphilis as a viral infection, instead of a sexually transmitted disease.
"There are fewer and fewer syphilis experts," he said. "I was a full-time medical schoolteacher at UCLA for 10 years. We gave about 15 minutes to syphilis."
Q: What is congenital syphilis?
A: Syphilis can be passed on to the fetus during pregnancy. Reports of congenital syphilis reached near-historic lows between 2000 and 2012, but in recent years, cases have started to surge. In 2012, 334 babies were born with congenital syphilis. In 2021, according to the CDC, there were nearly 2,700 cases - a sevenfold increase in less than a decade.
Matthew Golden, a professor and the director of the University of Washington Center for AIDS and STD, said congenital syphilis is "the most devastating consequence" of the "syphilis epidemic." In addition to causing stillbirths, the disease can cause bone deformities, jaundice, blindness and deafness in newborns.
Q: Who is most at risk for getting syphilis?
A: Any sexually active person could contract syphilis, and risk is highest among those who have multiple partners. The CDC recommends regular testing among sexually active gay and bisexual men, people with HIV and those taking pre-exposure prophylaxis (PrEP drugs) to help prevent HIV. Syphilis testing should also be done during pregnancy.
Some experts recommend a broader approach to testing: "The most important message is if you're sexually active, especially if you're sexually active with multiple different partners through the year, is to speak with your clinician or find an STD clinic where you can go and you can get evaluated and tested," said Michael Angarone, an infectious-disease specialist at Northwestern University.
Hilary Reno, the medical director of the St. Louis County sexual health clinic in Missouri, said the stigma attached to sexually transmitted infections means people often think they won't be the one to get a disease.
"Especially with syphilis - it surprises me how many people think that has gone away," Reno said. "They don't consider that something they can get during sex."
Syphilis isn't spread through casual contact, like touching doorknobs, clothes or using the same toilet seats as someone who's infected.
Q: Why is syphilis on the rise again?
A: A number of factors are probably behind the increase. Some public health experts say fewer people are using condoms, in part because the growing use of medications to help prevent HIV has lowered the incentive. They also pointed toward a relationship between the rise in opioid and methamphetamine addiction in the United States, which is associated with risky sexual practices.
In the early 2000s, there was a campaign to eradicate syphilis from the country. But public health experts say federal funding eventually ran out. "The whole infrastructure to prevent and control things like syphilis has completely eroded," Klausner said. "A lot of free STD clinics in a lot of cities and counties are just closed."
Golden said that in Washington, where he's the director of a center for STDs and HIV, health departments have "no ability to keep up with the workload" and the number of cases coming in.
"It's out of control. It's terrible. We're having huge problems," he said.
Q: How do you get tested for syphilis? What's the treatment?
A: Syphilis is diagnosed with a blood test, which you can get by going to your doctor or a clinic. There are also at-home tests you can buy at a drugstore or order by mail.
Home tests, which use a finger prick to collect a blood sample that's mailed to a lab, allow for privacy but can be expensive. Everlywell offers a single test for syphilis for $69 or a kit that tests for multiple STDs for $169. MyLabBox sells a single test for $89 or a "love box" to screen couples for eight diseases for $499. Let's Get Checked offers multi-STD home test kits that include syphilis, ranging from $149 to $249.
Syphilis is typically treated with one or more shots of penicillin, depending on the stage of the infection. If you're allergic to penicillin, there are other antibiotic treatments as well, Reno said.
Q: Can I get syphilis again?
A: Yes. If you've been treated for syphilis, you can get the disease again. You don't develop an immunity to the bacteria after an infection.
"People get syphilis again all the time," Golden said. "As a matter of fact, a strong predictor of getting syphilis is that you had it before."
Q: Is there a syphilis vaccine?
A: Not yet. The National Institutes of Health and the Gates Foundation are funding research for a vaccine, said Jonathan Parr, an infectious-disease professor at University of North Carolina.
Syphilis is a particularly tough disease to vaccinate against because the bacteria has adapted to escape our immune system. It replicates slowly in the body and is very good at moving from one person to another, Parr said. But researchers have recently found ways to more easily grow the bacteria in the lab and study its DNA.
"Syphilis has lagged behind other infectious diseases because of the challenges of working with this bacteria in the past, but I'm optimistic," he said. "We're on the cusp of seeing real progress forward."