Why Are So Many People Getting Syphilis? An Expert Explains the Uptick in Cases

Syphilis rates in the United States have been going up for about 20 years — along with other sexually transmitted infections. 

But in April, the Centers for Disease Control and Prevention reported that syphilis rates jumped by nearly 32% for all stages of the infection, with a total of 176,713 syphilis cases recorded in 2021. The last time cases were nearly this high was in 1950, when 217,558 cases were reported.

PEOPLE spoke to Dr. Edward Hook — professor at the University of Alabama at Birmingham and director of the STD Control Program for the Jefferson County Department of Health — about the resurgence, a well as what syphilis is and why there’s a recent influx in cases of the sexually transmitted infection.

What is syphilis?

Syphilis is a bacterial infection that is usually spread through sexual contact, according to the Mayo Clinic, and usually presents as painless sores that spread the disease. 

Because the sores don’t hurt, they often go undetected. However, the CDC says that while the sores will last 3-6 weeks regardless of treatment, it’s important to seek medical care to prevent the infection from progressing to the next, more dangerous stage.

At its early stage, syphilis can be cured with a single dose of antibiotics. But “without treatment, syphilis can severely damage the heart, brain or other organs, and can be life-threatening.”

While syphilis is on the rise, the CDC cautions that it cannot be spread through toilet seats, door knobs — or even from sharing utensils. The best way to avoid syphilis is by avoiding contact with the sores caused by the infection — so the CDC recommends using condoms if you are sexually active, although contact with the sores in areas not covered by a condom can still spread the disease.

Never miss a story — sign up for PEOPLE‘s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

RELATED: Syphilis Outbreak In Houston: Cases in Women Up 128%

Why are syphilis cases rising?

“Syphilis was lowest to start with in terms of the total population so it had the most room for increasing,” Hook notes.

Part of the reason cases of syphilis — as well as other STIs — are rising is because public health efforts to control these diseases are underfunded.

“In the past 20 years, the amount of money that goes to the CDC for STD control has remained level because of inflation. That means that the buying power of that funding is 40% less than it was 20 years ago. So it seems to me that the lack of resources is another important contributor to this problem.”

Additionally, syphilis cases are no longer present primarily among men who have sex with men.

“The current syphilis epidemic, of the past 10 or 15 years, started amongst men who had sex with other men,” he says. “But no surprise, it has then moved beyond men who have sex with men to involve men who have sex with women, and women who have sex with men, and other groups as well because people don’t exclusively partner with one kind of sex partner or another.”

Why are cases of syphilis in women increasing?

In addition to an overall rise in syphilis cases, the country has also seen an increase in women getting the STI, as well as a rise in congenital syphilis — which is when a mother with syphilis passes the infection to her unborn baby. According to the CDC, cases of congenital syphilis in the United States have “more than tripled” in recent years — although the disease was once “nearly eliminated.”

For example, the Houston Health Department reported this week that there was a 128% increase in congenital syphilis in Houston and Harris County — a rise that is similar to that of other cities across the United States.

“Congenital syphilis rates are now higher than they’ve been in the United States in more than 25 years. There are several reasons for that,” Hook says. “One is that this mirrors the general increase in syphilis and the movement of the syphilis epidemic from men who have sex with men into heterosexual population.”

“Second is that women with syphilis are disproportionately ethnic minorities, racial minorities, and those are people who have less ready access to healthcare than other populations,” he continues. “So, if you look at the simplest rates in the United States, you’ll see that the rates have gone up disproportionately amongst Hispanic women and Black women — the same groups who have other challenges with regards to access to healthcare, prenatal care, etc.” 

Although cases in women are rising, Hook assures that these rates do not mean that women are more susceptible to syphilis. “It’s not a vulnerability issue,” he stresses. “There is no data whatsoever to suggest that one group or another is more vulnerable to acquiring syphilis than others.” 

RELATED: STDs in the U.S. Are ‘Out of Control’ After Syphilis Cases Spiked 26% Last Year

RELATED: Gonorrhea Strain that Resists Many Antibiotics Identified in the U.S.

What is the key to decreasing overall syphilis cases?

Hook emphasizes that the national rate of syphilis cases could easily be lowered if there was greater investment in public health in the United States. 

That investment involves increasing availability of and accessibility to preventive and care services, increasing education about screening and treatment, and focusing those efforts on underserved populations.

“We’ve proven again and again — most recently in the early 1990s — that if you make it a priority and you put resources into it, you can control this disease,” Hook tells PEOPLE. “Syphilis rates in the United States by the mid 1990s were the lowest that they’d been in decades. That was because there had been an epidemic of syphilis in the late eighties and early nineties that became a CDC priority. CDC put resources into it, the Congress of the United States helped fund syphilis control programs and rates plummeted.” 

He adds, “The rates got so low that people said, ‘We’re in good shape, we can now reallocate resources to other purposes.’ And they did. The disease smoldered for a while, and then came back in a new vulnerable population this time, men who had sex with men.” 

How often should people get tested for syphilis?

“That answer is different for everybody,” Hook admits. “In general, the more partners a person has, the more often they should be checked. We would suggest that everybody be checked at least once. For the people who are in stable, monogamous relationships and are confident that their partners are similarly monogamous, one test should be enough. If there are questions about monogamy, testing periodically — perhaps once a year — is reasonable. For people who have more than three, four sexual partners in a year, testing as frequently as every six months might be a good idea.”