Just in time for Valentine’s Day, researchers from the U.S. Centers for Disease Control and Prevention issued two new studies of sexually transmitted infections (STIs) today detailing what the lead author of one calls “an ongoing, severe, STI epidemic.”

The studies reveal new infection data, some of it available for the first time, for the eight most common STIs -- chlamydia, gonorrhea, syphilis, herpes, human papillomavirus (HPV), hepatitis B, HIV, and trichomoniasis. The studies, which estimate infection rates and medical costs related to STIs, were published in the journal Sexually Transmitted Diseases.

Both are startling. In 2008, there were 20 million new incidents of infection in the United States, and a prevalence (new infections plus ongoing infection) of 110 million, according to CDC estimates. (Because one person may have more than one infection, the 110 million figure does not mean 110 million people have a sexually transmitted disease.) As a result, the United States incurred estimated direct medical costs of nearly $16 billion.

Previous such estimates, for years 1996 and 2000, estimated approximately 15 million and 18.9 million new incidents respectively, though these reports used somewhat different data sources and methodology so the CDC cautions against making direct comparisons. According to the Henry J. Kaiser Family Foundation, the American Social Health Association, and the CDC, the U.S. has the highest rate of STIs in the industrialized world.

“STIs take a big health and economic toll on men and women in the United States, especially our youth,” CDC epidemiologist Catherine Lindsey Satterwhite, who led the study of incidence and prevalence, told NBC News. 

Although people age 15-24 account for only 25 percent of the nation’s sexually experienced population, Satterwhite’s study estimates they account for about half of all sexually transmitted infections.

Because every STI is preventable, Satterwhite argued, “we know that preventing STIs could save the nation billions of dollars each year.”

The story could have been different, insisted Matthew Golden, the director of Public Health Seattle and King County HIV/STD Program and a professor of medicine at the University of Washington Center for AIDS and STD. The good news, he said, is that rates for most viral and bacterial infections, including HIV, have stabilized or even dropped.

The “epidemic” Satterwhite speaks of, he said, is driven almost entirely by two bugs: HPV, and chlamydia. Chlamydia, a bacterial infection, is easily curable if it’s diagnosed. And there’s a very effective vaccine for the most dangerous forms of HPV that can trigger cervical, oral, anal, and penile cancers, and cause genital warts.

But, Golden argued, “we have snatched defeat from the jaws of victory” by not pursuing effective strategies, such as school-based universal access to the HPV vaccine.

Only about 35 percent of American girls age 13-17 had received the complete course of HPV vaccine as of 2011, according to the CDC. The rate among boys was about 28 percent. In comparison, Australia’s National HPV Vaccination Program provides the vaccine to girls at age 12 and 13 through their schools. As a result, 72 percent of girls have received a complete vaccine by age 15. (Boys were added to the program this year.)

Satterwhite’s study estimated 14.1 million new HPV infections during 2008 and a prevalence of 79.1 million, making it the most common STI by far. While the majority of HPV infections are cleared by the body’s immune system, some are not.

“How could we possibly have done this to ourselves?” Golden asked. “We have a solution; we have to make it happen.”     

Chlamydia can go undiagnosed if it doesn’t cause symptoms and since many young people are not routinely screened, cases can go untreated. This can result in pelvic inflammatory disease (PID) infertility, and ectopic pregnancies. A 2004 study from CDC epidemiologists and economists estimated that “costs per case of PID, including those associated with acute PID, chronic pelvic pain, ectopic pregnancy and treated infertility, range from $1,060 to $3,626.” 

Meanwhile, STI prevention and awareness programs targeting other infections are also critical. For example, Satterwhite estimated 820,000 new gonorrhea infections in 2008. While the U.S. has largely escaped it so far, drug-resistant gonorrhea is slowly spreading around the world. Condoms offer protection against gonorrhea, as well as chlamydia, HPV and other STDs, something to consider before that Valentine’s Day date. 

Brian Alexander (www.BrianRAlexander.com) is co-author, with Larry Young Ph.D., of "The Chemistry Between Us: Love, Sex and the Science of Attraction," (www.TheChemistryBetweenUs.com), now on sale.

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Carlo Joyce, right, and Thomas Joyce share a moment on their wedding day on July 10, 2010.

As a teenager, Carlo Joyce’s relationship with his parents was strained. He’s gay, but hid that fact from family and most of his friends. So he usually found himself lying when his folks asked where he was going and with whom.

“After I came out at 19, things got better with my family,” he recalled. But then he joined the Marines and had to hide his sexuality all over again.

He had to go to strip bars to fit in, and when the other guys talked about sex, or dating, he had to be sure he changed the gender in his stories. “It was very stressful to live that double life,” he explained. “I always had to watch what I said.”

Now, in a study released today in the journal Psychosomatic Medicine, a team of psychologists and neurologists from McGill University and the University of Montreal has found that leading that double life affects physical and mental health. Gays, bisexuals and lesbians who disclosed their sexuality to family, friends and co-workers were psychologically healthier and had lower levels of a key stress-related hormone than those who were still “in the closet.”

That finding could help explain a remarkable study published last year by a group of researchers from Columbia University in the American Journal of Public Health. They found that after Massachusetts enacted its same-sex marriage law in 2003, there was a significant drop in medical and mental health care visits -- and therefore costs – incurred by gay men.

Lead author of the Montreal study, Robert-Paul Juster, a PhD student at the Centre for Studies on Human Stress at the University of Montreal, said “it seems to be that if you’re using more avoidance coping, and wishful thinking, then you get poorer health. If you aren’t dealing with the problem, it affects health in a negative way.”

On the other hand, dealing with the problem by transitioning from “in” to “out” can instill a great sense of accomplishment. “A rebirth happens that makes them feel much more empowered and conscientious” for having taken what many see as a risky action. That sense of empowerment can have ripple effects benefitting overall health and well-being.

Juster’s study was complex. It included 87 people with a mean age of about 25, 46 of whom were lesbian, gay, or bisexual, and 41 of whom were heterosexual. There were slightly more men than women.

All the participants completed a battery of psychological testing to gauge traits like depressive symptoms, chronic stress, burnout, anxiety and conscientiousness. Blood samples were taken by the researchers, and the participants collected their own urine and saliva at five time points each day for two consecutive days. These were tested for a series of 21 biomarkers related to immune function, metabolism, inflammation, the cardiovascular system, and the endocrine system.

When all the numbers were sifted, and differences like social and economic status were controlled for, it turned out that disclosed sexual minorities had fewer symptoms of depression.

They also had lower cortisol levels 30 minutes after waking. That’s important because cortisol, a key stress hormone, spikes about half an hour after we wake up, like an ignition spark getting us ready to face the day. But you don’t want too much or too little. Disclosed gay men and lesbians were just right. In fact, dislcosed gay men also had lower cortsone levels than straight men.     

Juster isn’t sure why, exactly. It could be because the gay men were in better physical shape. It could also be that because heterosexual men have never had to go through the stress of living life undercover, they’re less practiced at coping and so less resilient to life’s stress.

Joyce, now 33, and living in San Diego, has had a lot of practice. He’s an engineer at a large corporation. When he first started that job, he again hid his sexual orientation, from co-workers and bosses.

“It was like I was back in the closet,” he said. The hiding was self-imposed, but stressful all the same. “Once I did come out, it was much less stressful and I found great acceptance and support.” When he married his partner, many of his co-workers attended. (To clarify, the July 10, 2010, wedding was not a legal marriage as recognized by the state.)  “Life’s much easier,” he said.

Brian Alexander (www.BrianRAlexander.com) is co-author, with Larry Young Ph.D., of "The Chemistry Between Us: Love, Sex and the Science of Attraction," (www.TheChemistryBetweenUs.com), now on sale.

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Before Lance Armstrong’s reported confession to Oprah Winfrey that he used performance-enhancing drugs, the former cycling champ had long deflected the relentless rumors by suggesting that, after his experience with near-fatal cancer, such drugs would be dangerous.

In 2007, he told an audience at the Aspen (Colo.) Ideas Festival, “I came out of a life-threatening disease. I was on my death bed. You think I'm going to come back into a sport and say, ‘OK, OK doctor, give me everything you’ve got, I just want to go fast?’ No way! I would never do that.”  

Armstrong may have used his cancer as a defense but questions about his use of performance enhancers have dogged him for years. This summer, the United States Anti-Doping Agency stripped him of his titles as part of the United States Postal Service cycling team going back to Aug. 1, 1998, the same year he began his comeback after his 1996 diagnosis and treatment of testicular cancer that had spread to his lungs and brain.

His teammates testified, according to USADA documents, that over the course of his cycling career, Armstrong used recombinant erythropoietin (EPO), an artificial hormone that stimulates red blood cell production and, some athletes believe, may fuel their muscles' ability to perform; androgen hormones (versions of the testosterone molecule); “blood doping,” the practice of infusing one’s own (or somebody else’s), stored blood into the body as a way to increase oxygen-carrying red blood cells; cortisone; and Actovegin, a product derived from calf’s blood that is thought by some athletes to increase endurance.

It's not known yet exactly what Armstrong himself has admitted to taking or how long he took them. But, if he used the performance-enhancing drugs (PEDs) that his teammates say he did, could they have affected his hard-fought recovery from cancer, or compromised the body he said he was trying so hard to protect?  

Research does suggest that EPO might possibly fuel some existing cancers, but so far there’s no specific research on testicular cancer cells. Certain types of cancer cells, like breast, renal and colon, are sensitive to the EPO hormone, explained Scott Drab, associate professor of pharmacy and therapeutics at the University of Pittsburgh School of Pharmacy. Drab, who advises doctors on how drugs affect the body and various disease states, said, “EPO does have properties that can proliferate cell tumor growth.”

EPO is used as part of cancer therapy because it combats sometimes life-threatening anemia, a common side effect of chemotherapy. Some studies have shown EPO is safe when used carefully while others have suggested a possible link to worse outcomes for cancer patients. Some studies seemed to indicate statistically significant lower survival rates following EPO use in cancer patients. Other studies appeared to contradict such results, but, out of caution, the FDA issued a “black box” warning in 2007 advising doctors to use the lowest possible dose. 

"The consensus is that we still don’t know” EPO’s full effect on cancer, said Dr. Bartosz Chmielowski, an oncologist at UCLA's Jonsson Comprehensive Cancer Center.

“It is generally a bad idea to take drugs you don’t need,” he said, in response to a question about PEDs effects on anyone, not just a cancer survivor like Armstrong.

Even in a person with cancer, he explained, EPO should be used “only in cases when somebody is undergoing chemotherapy and that’s causing anemia and there are not any other causes of anemia.” The only other time anybody who’s had cancer should be using the drug, he said, is if the disease is terminal and doctors want to improve quality of life and avoid transfusions.

Dr. Norman Fost, a pediatrics professor and director of the bioethics program at University of Wisconsin School of Medicine and Public Health, has written extensively for 20 years about performance-enhancing drugs.

He's known as an opponent of "steroid hysteria," but, he said that while “there’s just no scientific proof of any such association” showing steroid use triggers cancer, “I wouldn’t be surprised to see a rise in prostate cancers 30 years from now among people who used [androgenic, related to testosterone] steroids” since it’s known that prostate cancer can be fueled by androgens.

Brian Alexander (www.BrianRAlexander.com) is co-author, with Larry Young Ph.D., of "The Chemistry Between Us: Love, Sex and the Science of Attraction," (www.TheChemistryBetweenUs.com), now on sale.

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