Doctors seeing more syphilis patients with unusual and severe symptoms, study shows

(CNN) — Disease detectives in Chicago say they have been seeing a worrisome trend: Patients complaining of unusual symptoms like vision and eye problems, headaches and hearing loss or dizziness caused by the sexually transmitted infection syphilis.

Doctors have long known that syphilis can permanently damage a person’s vision and hearing and can even lead to psychiatric changes, but these symptoms are usually associated with infections that have gone undiagnosed and untreated for years.

In a new study presented on Wednesday at the 2024 Epidemic Intelligence Service Conference in Atlanta, researchers say there were more than two dozen cases with these kinds of symptoms in Chicago last year, and nearly a third of the cases were in the early stages of their infections.

More than two-thirds of these patients (68%) lacked typical syphilis symptoms, like a rash or chancre sore, that might tip doctors off to the infection.

“Providers definitely need to be screening more and be aware that this is what we’re seeing,” said lead study author Dr. Amy Nham, who is a first year EIS officer, or “disease detective,” assigned to the Chicago Department of Public Health.

Syphilis cases are surging across the US. In 2022, there were more than 207,000 syphilis cases reported, the highest number since the 1950s, according to the US Centers for Disease Control and Prevention.

Men who have sex with men have traditionally had the highest burden of syphilis in the US, and that’s still true; but in recent years, the demographics of the infection have been shifting, and infections have more than doubled in heterosexual men and women since 2019. Congenital syphilis, where the infection is passed from a pregnant woman to her baby, is also on the rise.

Nham said she was asked by her supervisors at the Chicago Department of Public Health to look into cases with unusual symptoms — called NOO syphilis, for neurosyphilis, ocular syphilis, and otic syphilis — after hearing that providers across the city were seeing more of them.

She searched a citywide repository of medical records to look for cases of patients who had signs or symptoms consistent with NOO syphilis and 28 people met her case definition. Most (75%) were men and Black (71%). The patients ranged in age from 23 to 82 years. Six were gay men, but about half said they were heterosexual. One in three was HIV positive, which was a lower percentage than Nham said she expected, given that people living with HIV generally have more severe symptoms of syphilis. In the latest CDC data, more than one-third of gay men with primary and secondary syphilis also had HIV.

Nham’s study found the most common symptoms patients experienced were headache, personality changes or altered mental status, and eye problems like vision loss, sensitivity to light or swelling in the eye.

“They’re not the most specific symptoms, which is why it’s really important that providers are doing appropriate screening and asking patients for risk factors,” and things like their sexual history, Nham said.

Syphilis is caused by bacteria called Treponema pallidum. The infection progresses in stages. People catch it when they come into contact with a round, firm and painless sore called a chancre, which typically appears on the genitals, lips or tongue. The chancre marks the first stage of the infection. These sores can last for 3 to 6 weeks, and may eventually go away on their own, without treatment. Sometimes people may not notice them because they might be small or in a place that’s hard to see.

Syphilis is a wily infection.  Its symptoms come and go and can look like a lot of other ailments, leading doctors to dub it “the great imitator.”

After the chancre clears up, it may seem like the infection is cleared, but it has just gone into hiding. The second stage of the infection usually starts with rashes or lesions in the mouth. People also usually feel unwell — they can have a fever, swollen lymph nodes, fatigue, sore throat, muscle aches, hair loss and weight loss.

Syphilis can progress to a third stage if left untreated. The third stage emerges 10 to 30 years after the initial infection and can be fatal.

At any point in the infection, the bacteria can invade the nervous system leading to brain, eye and ear involvement. This may include things like headaches, brain swelling called meningitis, strokes, and mental changes. Eyes may be sensitive to light or swollen, or sight may be affected. People can also experience hearing loss, dizziness, or tinnitus if the infection reaches their ears.

Nham’s study only looked at Chicago, but she has been collecting case reports and says doctors are seeing similar things in other parts of the country.

She said she doesn’t know for sure why they’re seeing more cases with these atypical symptoms — that was beyond the scope of her study — but she has some theories.

The preferred treatment for syphilis is an injection of a long-acting form of the antibiotic penicillin, called Bicillin L-A, which has been in shortage for a year.

Because the injections are the only treatment that’s effective in pregnancy, the CDC has advised that health-care providers prioritize those shots for people who are pregnant and babies.

Men can take a different antibiotic — doxycycline — to cure their infections. But, doxycycline is a pill that has to be taken twice a day for several weeks to be effective, and some people don’t finish the full course, which may allow their infection to smolder and get worse.

“There could just be an increase in untreated or inadequately treated patients, which is leading to more severe outcomes of syphilis,” Nham said.