Syphilis Is Rising in the U.S. Here's What to Know About the Sexually Transmitted Infection

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Sexually transmitted infections are rising in the U.S.—particularly syphilis, which increased by 26% from 2020 to 2021, according to preliminary data from the U.S. Centers for Disease Control and Prevention (CDC) published in September. Especially troubling is a 24% rise during that time period of congenital syphilis, which infects fetuses in the womb and can cause birth defects in or even kill infants.

Fortunately, syphilis can be easily treated and cured. However, people who are infected don’t necessarily know it—and without detection and treatment, the disease can have devastating consequences.

Here’s what you need to know about the rising rates of syphilis and how to protect yourself.

Why syphilis is on the rise

Syphilis dropped to a historic low in 2000 but has increased almost every year in the U.S. since then. Experts say that’s for several reasons, including a lack of investment in public health in the U.S. and stigma surrounding sex, says Dr. Edward Hook, a professor at the University of Alabama at Birmingham and director of the STD Control Program for the Jefferson County Department of Health. Public-health clinics, where people often get STI tests, are chronically underfunded in the U.S. The COVID-19 pandemic made the situation worse, since under-staffed public-health clinics redirected resources to cope with the outbreak. Given that syphilis has had tests and treatments for decades, says Hook, the fact that it keeps resurging “is a marker that we’re doing something wrong.”

Meanwhile, says Hook, American health care providers aren’t necessarily trained to competently deal with sex or sexuality, so they often miss crucial screening opportunities. “Most doctors do not take sexual histories [of their patients], and an even smaller proportion take interval sexual histories once people have become regular patients,” says Hook. “They make wrong assumptions that married persons don’t have other sexual partners—that their patients aren’t ‘that kind of patient’ who might have other sexual partners.”

Other factors include the rise of online dating, which some experts say enables people to expand their sexual network and has been connected to riskier sexual behavior, and the growth of illicit drugs in the U.S., especially methamphetamine. The use of these drugs tends to be connected to risky sexual behavior. Another factor is that many people are generally tired of using condoms, says Dr. Ina Park, an associate professor of family community medicine at the University of California, San Francisco, and author of Strange Bedfellows: Adventures in the Science, History, and Surprising Secrets of STDs. For example, “most people don’t use condoms for oral sex—and syphilis is one of those STIs that can be easily transmitted through oral sex,” says Park.

Who should get tested for syphilis—and how often?

On Sept. 27, the U.S. Preventive Services Task Force, an independent panel of medical experts, reaffirmed its guidance for health care providers to screen all patients who are at increased risk for infection.

The task force didn’t make recommendations about how often people should be tested, noting that ideal screening intervals for people at increased risk are “not well established.” It did say that two of the highest risk groups–men who have sex with men, as well as people with HIV— “may benefit” from being screened once a year or even more frequently. CDC data show that men who have sex with men are 106 times more likely to be infected with syphilis than men who have sex with women. The CDC recommends that men who have sex with men should get tested for syphilis as often as every three to six months if they have multiple or anonymous partners. Other groups at elevated risk for syphilis include Black Americans, who are nearly five times more likely to be infected than white Americans. Socioeconomic factors—including having less access to good health care—can also make people more vulnerable.

Syphilis can be detected with a simple test at a clinic (which is typically free or inexpensive), and is curable with antibiotics. People can reduce their risk of contracting syphilis with safe-sex practices including using condoms, getting tested, and being in a monogamous relationship with someone who has also tested negative, according to the CDC.

Sexually active people should get screened for syphilis, along with other STIs, about once a year, says Park. People should also be tested for syphilis early in pregnancy. Pregnant people at higher risk for syphilis—including those who are having sex with more than one person, have tested positive for another sexually transmitted infection during pregnancy, or who use drugs—should be re-tested in the third trimester and at birth.

What are the symptoms of syphilis?

Syphilis has a reputation for being easy to miss and for being mistaken for other conditions. In the infection’s early stages, people may have sores on their genitals or mouths, but these bumps may be internal and therefore not easily visible. They’re not always painful and clear up on their own, so many people ignore or don’t notice them. A few weeks or months later, however, people with syphilis typically develop multiple sores or rashes on their genitals, mouth, or soles of the feet. This can resemble symptoms of other conditions, like psoriasis, herpes, or eczema. During these two stages, syphilis is highly contagious and can be spread through kissing and vaginal, anal, and oral sex.

The rashes and bumps typically clear up, but the infection remains in a person’s body. Without treatment, syphilis can cause harm years or even decades later, damaging the nervous system, the brain, and the heart, Park says. However, serious symptoms can occur at any stage if the infection spreads to the brain, eyes, or ears, including damage to vision or hearing or even dementia. In some cases, however, people may not realize they have syphilis until the disease has already caused harm, says Park.

Even when it doesn’t cause symptoms for years or even decades, “it’s still multiplying and causing damage,” she says.

Getting tested and treated for syphilis is particularly important for pregnant people. Congenital syphilis raises the risk of miscarriage, stillbirth, premature birth, low birth weight, or the baby dying soon after birth. Babies who survive can also develop symptoms like deformed bones, meningitis, and problems with their brain. Babies don’t always have symptoms at birth, but can develop them a few weeks or even years later—so staying up to date on testing is crucial.