On September 26, the Centers for Disease Control and Prevention announced that STDs had reached unprecedented numbers in the United States...for the third year in a row. The reported cases of chlamydia, gonorrhea, and syphilis in 2016 were at record highs: nearly 1.6 million chlamydia cases, almost 470,000 gonorrhea, and 27,000 of primary and secondary syphilis. (Those are increases of 5 percent, 19 percent, and 18 percent, respectively, since 2015.) And those are just the reported cases of three major STDs: The CDC estimates that there are 20 million new sexually transmitted infections every year.

Along with these numbers, the CDC released a fact sheet noting which groups were most at risk and their recommendations for whom STD screening is "critical"—all sexually active women younger than 25, women with new or multiple sex partners, pregnant women, and sexually active gay and bisexual men. (The recommendations are also outlined here.)

CDC Fact Sheet, September 2017

Uh, what about sexually active straight men? Presumably there are many women getting STDs from their heterosexual partners—so why are these men seemingly off the hook when it comes to testing? While the CDC says each case is individual, they also claim there's no evidence that widespread screening of heterosexual men leads to benefits for the whole population, even if it theoretically could cut down on STD transmission.

"At first blush, it does seem like the more people you test, the more you democratize the process," says Jeanne Marrazzo, a professor of medicine and the director of infectious diseases at the University of Alabama, Birmingham. Marrazzo isn't affiliated with the CDC; she works in the biomedical prevention of HIV and STDs in people at risk both in the US and abroad.

She says that, even in her own research, the CDC's claim holds up—it's been hard to say that screening heterosexual men has much reward. She says that for screening to be broadly recommended, it must fit three criteria: The infection should be reasonably common in the population, there needs to be a good screening test for it, and most importantly, when you treat it, you're preventing a bad outcome.

"You would have to show that treating them either helped their future health, or it prevented them from transmitting the infection to women," she says. "We have not been able to show that screening asymptomatic, heterosexual men will fill those criteria."

The stakes in testing for chlamydia and gonorrhea are naturally higher for women. They're screened not to eradicate the infection, but to prevent the worst consequences of those infections can have on pregnancy and reproductive health, according to David Soper, a professor of obstetrics and gynecology at the Medical University of South Carolina in Charleston and a practicing gynecologist.

Untreated chlamydia and gonorrhea in pregnant women is linked to miscarriage, premature labor, and low birth weight, and in others it can lead to infertility-causing pelvic inflammatory disease and dangerous upper genital tract infections. For men, the consequences of these diseases are not as severe (though chlamydia can affect sperm quality), so spending already-limited STD funding on them could potentially detract from what we can offer women.

The CDC says that's the other driver behind their recommendations: There just isn't enough money to go around. The CDC is the only government agency that directly supports STD prevention by state and local health departments. In fact, the majority of the CDC's STD prevention budget goes directly to 50 states and 9 cities and territories to support such prevention programs. More than half of that budget goes to a program called STDAAPPS, which lets states direct funding to where they need it the most. This includes anything from improving their STD surveillance programs, using electronic laboratory reporting, funding collaborations between public health services and primary care services, or supporting collaboration with state Medicaid programs and health insurance exchanges.

"Federal funding for STD prevention and control is already low, so while millions of Americans have had an STD, it is important to focus efforts on the groups, including young women and gay and bisexual men, who are disproportionately affected," says CDC spokesperson Elizabeth Davenport.

Americans aged 15 to 24 account for half of those estimated 20 million new STDs in the US each year, and health consequences are most severe for young women—so it's critical to apply the resources we have to them. In gay and bisexual communities, STDs have skyrocketed, Marrazzo says, and they need our attention and resources as well.

There are caveats, of course. The CDC screening recommendations only apply to asymptomatic people (even though they acknowledge that straight men can be asymptomatic carriers). Anyone—gay or straight, male or female—who has symptoms of an STD should get tested and treated, Marrazzo says. And routine screening of heterosexual men can be put into practice in communities that are especially vulnerable, like juvenile detention centers, or cities with high rates of chlamydia and gonorrhea.

The CDC also facilitates a program called Expedited Partner Therapy (EPT), in which the sex partner of someone diagnosed with chlamydia or gonorrhea can get antibiotics without being examined. They're still encouraged to see their doctor and this would apply, presumably, to the heterosexual partners of women. (Kentucky and South Carolina prohibit EPT—thanks, guys—but even in the other 48 states, providers aren't required to offer it.)

EPT sounds like a great option for partners, but it still feels like women have to bear the burden of sexual health for hetero men. They partake in the screening, doctors' appointments, and then their partners get rushed through the process without even needing to be examined. Soper says while it may seem unfair, that women should view it not as carrying the sexual burden, but having the power.

"I think women have a lot of power and authority over whether they want to have sex or not," he says. "And so they can insist on making sure their partner is not infected with an STI, just like they can insist that that partner use a condom. I would support and promote that kind of freedom of choice to keep themselves safe."

The other practical issue, he says, is that it doesn't make sense to rely on heterosexual men who rarely go to the doctor. Even if screening them could provide some benefit, he doubts they would keep regular appointments. "I don't believe that they would show up," he says. "Some will. But most won't."

Still, as a sexually active woman reading the recommendations and finding that heterosexual men are excluded, I feel a little ripped off. Merely accepting that men "won't" go to the doctor and continuing to take all the responsibility only seems to encourage those behaviors.

"What you're saying really resonates with me because women have traditionally taken the responsibility ourselves," Marazzo says. "And part of that is that young, healthy guys don't go to the doctor, right? Women are a captive audience. They go in for birth control, they go in for Pap smears. What it says to me is that we haven't figured out the right approach to get them involved.

"Is screening the right approach? Maybe. Somebody should look at that harder. Perhaps this is an opportunity to get these guys to take more responsibility and control for their sexual health, and their partner's sexual health."

Even though the reasons behind the CDC's screening criteria are entirely practical, it definitely doesn't do much to help to alleviate the stigma of STDs when only women and gay and bisexual men are told to get tested for disease. By classifying groups based on gender or sexual orientation rather than behavior, screening criteria can encroach on dangerous territory.

"I do think there is a very fine line between the issue of stigma and infections that are associated with shame," Marrazzo says. "There are areas where you certainly don't want screening criteria to go. If you look by race in the US, especially gonorrhea and trichomoniasis, the populations that are most affected are African American. Nobody would ever say that screening should be based on those criteria. Rather, what we need to look at is why? Why are we seeing those trends and are there ways to characterize their vulnerability to these infections that could help us guide the intervention?"

The US Preventive Services Task Force (USPSTF) is an independent panel of experts in prevention and evidence-based medicine that makes recommendations on clinical preventive services, and they say they don't make their STD screening recommendations based on sexual orientation, but rather by sexual behavior.

The USPSTF has separate recommendations for syphilis and chlamydia and gonorrhea. For the latter two STDs, the Task Force says there isn't enough evidence to show that screening men is beneficial. When it comes to syphilis, the USPSTF recommends screening for all asymptomatic adults and adolescents who are at an increased risk of infection and, wouldn't you know it, that group includes men under 29. (It's worth noting that the Task Force doesn't consider the costs of a preventive service when determining its recommendation grade, and the CDC cites cost as a reason why it focuses on testing for women and gay and bisexual men.)

The recent CDC report shows that men ages 20 to 34 had the highest rates of syphilis in 2016, with the 25 to 29 and 20 to 24 age groups leading the charge, which jibes with the USPSTF recommendation. While the majority of the cases are among gay and bisexual men, the report also found that, in 36 states with data on sexual orientation, rates of syphilis are still higher among heterosexual men than among women. Not only that, but increases in syphilis rates from 2015 to 2016 were higher in women and straight men than among gay and bisexual men (increases of 31 percent, 22 percent, and 16 percent, respectively). Syphilis is increasing among all Americans, no matter their gender or sexual orientation, and yet the CDC still uses gender and sexual orientation as benchmarks for who should get tested.

"The Task Force focuses on high-risk behavior when making recommendations for screening for sexually transmitted infections because these behaviors can be displayed by a variety of people, regardless of their sexual orientation," says Task Force chair David Grossman, a pediatrician and senior medical director for the Washington Permanente Medical Group. Though the USPSTF still agrees that studies show heterosexual men don't usually need to be screened, categorizing by behavior better encompasses people's actual sex lives.

"A person's sexual orientation does not necessarily imply that they will exhibit high-risk behavior," he says. Of course, high-risk behavior means not using condoms, having multiple sex partners, and not getting tested and treated for STDs. The CDC recommends practicing mutual monogamy and using condoms from start to finish for oral, anal, or vaginal sex (but let's face it, almost nobody uses them for oral).

Soper says he's seen gonorrhea "clusters" or outbreaks, where one person is responsible for eight other cases, and those eight who were infected only caused one or two more infections. The higher-risk person—the one who infected eight people—would be the good person to screen and treat, despite their gender or orientation. But Soper says there's a problem to structuring screening this way, just like asking straight men to go to the doctor: it requires some proactivity that he's not sure is realistic.

"This would require self-identification, and seeking out a health department or physician for care," he says. "But that's only if they can self-identify as high risk, and then go in for routine check ups, and be screened, then I think that would be useful."

It may all seem like semantics—which groups get screened and when—but Marrazzo thinks it's important. She recently wrote a chapter for an updated version of a contraceptive textbook, and for the first time she and the authors tried to make the text gender neutral.

"We are also recognizing that gender is a personal construct and identity," she says. "It was really fun, because I had never tried to frame it that way before, and it was much easier than I thought. I think referring to 'persons' and their behaviors is a great way to think about this. It gets away from putting people in boxes, which screening criteria has always been very good at doing. It makes it much more about what they're doing at that time in their lives to put themselves at risk for that condition."

She says the only possible risk of gender-neutral guidelines is creating screening recommendations that are too vague. But with some work, it's possible to write criteria that help those who need it without causing stigma or categorization.