With rates of syphilis rising quickly in the United States and elsewhere, clinicians are having to up their game when it comes to diagnosing and treating an infection that they may not be paying enough attention to.
More than 200,000 cases of syphilis were reported in the United States in 2022, which is the highest number since 1950 and is a 17.3% increase over 2021, according to the latest figures from the Centers for Disease Control and Prevention (CDC). The rate of infection has increased almost every year since a historic low in 2001.
And the trend is not limited to the United States. Last year, the infection rate in the United Kingdom hit a 50-year high, said David Mabey, BCh, DM, from the London School of Hygiene and Tropical Medicine. Syphilis and other sexually transmitted infections are also a major problem in low- and middle-income countries, he added, although good data are not always available.
Many of today’s healthcare professionals have little experience with the disease, shared Ina Park, MD, a sexually transmitted infections specialist at the University of California at San Francisco. “An entire generation of physicians — including myself — did not see any cases until we were well out of our training,” Dr. Park reported. “We’re really playing catch-up.”
A Centuries-Old Ailment
Dr. Park offered some advice on the challenges of diagnosing what can be an elusive infection at the Conference on Retroviruses and Opportunistic Infections (CROI) 2024 Annual Meeting in Denver. That advice boiled down to one simple rule: “Test, test, test.”
Because syphilis can mimic so many other conditions and can have long periods of latency, it can be easily missed or even misdiagnosed by experienced physicians, said Dr. Park. Clinicians need to keep it front of mind and have a lower threshold for testing, even if there are no obvious symptoms.
Following the CDC’s new recommendations for syphilis screening will help, she noted; every sexually active patient aged between 15 and 44 years who lives in a county with a syphilis infection rate of 4.6 per 100,000 people or higher should get the test. And clinicians should remain vigilant, even in areas with a lower prevalence. “If you can’t account for new symptoms in a sexually active patient, order a test,” said Dr. Park.
Complicated Cases
The lack of experience with syphilis affects not just diagnosis but also treatment, particularly for complex cases, said Khalil Ghanem, MD, PhD, from the Johns Hopkins University School of Medicine in Baltimore. “When you don’t have to deal with something for a while, you forget how to deal with it,” he added.
At CROI, Dr. Ghanem offered suggestions for how to navigate complicated cases of ocular syphilis, otic syphilis, and neurosyphilis, and how to interpret test results when a patient’s antigen titers are being “unruly.”
With potential ocular or otic syphilis, you shouldn’t wait for a specialist like an ophthalmologist to weigh in but instead refer the patient directly to the emergency department because of the risk that the symptoms may become irreversible and result in permanent blindness or deafness. “You don’t want to dilly-dally with those conditions,” Dr. Ghanem said.
Closely monitoring a patient’s rapid plasma regain and venereal disease research laboratory antigen levels is the only way to manage syphilis and to determine whether the infection is responding to treatment, he noted, but sometimes those titers “don’t do what you think they should be doing” and fail to decline or even go up after treatment.
“You don’t know if they went up because the patient was re-infected, or they developed neurosyphilis, or there was a problem at the lab,” he said. “It can be challenging to interpret.”
To decipher confusing test results, Dr. Ghanem recommended getting a detailed history to understand whether a patient is at risk for reinfection, whether there are signs of neurosyphilis or other complications, whether pregnancy is possible, and so on. “Based on the answers, you can determine what the most rational approach to treatment would be,” he shared.