In a post last month we established that folks over 50 are reentering the singles scene with seriously outdated information about the sexually transmitted infections (STIs) that have become commonplace since their own prom nights.

When it comes to older people and STIs, “don’t ask; don’t tell” is the MO. Doctors don’t think to ask Grandma about her sex life, and Grandma sure ain’t talking.

“What we are really witnessing with trichomonas, especially in older women, is that no one ever looked, no one ever tested and diagnosed, and no one is really getting treated, so the infection persists year after year,” said Charlotte Gaydos, a professor at Johns Hopkins School of Medicine in a news release.

And what is true for trichomonas, is true for all the other nasty little STIs— These infections respect neither age nor social status. Anyone can get an STI. Even Grandma.

So, in this post and one more, we’ll give you a primer on the most common STIs circulating now. (Yes, this is the short list.) The topic is complex and evolves quickly, so if you’re sexually active and especially if you have a new partner or several partners, talk to your doctor about prevention and getting tested.

Finally, if this information doesn’t scare the bejeesus out of you, then you have a higher tolerance for risk than is probably good for you.

First, a few general observations.

  • Get an annual pelvic exam. New guidelines from the CDC now recommend annual pelvic exams and Pap tests every three years. But if you have a new partner, tell your doctor.
  • If you have a new sexual partner, insist on using a condom (properly) until you are both absolutely certain nothing is getting passed between you. It can take several months for infections like HIV to show up on a test.
  • Both you and each new partner should be tested for STIs. (See the last post.)
  • Drug and alcohol use impairs judgment and leads to more risky sexual behavior. (Yes, that means you.)
  • Condoms help, but they’re never 100 percent effective. Some viruses can be on places not covered by the condom.
  • One infection reduces your ability to fight off others. This is especially true with HIV, that’s why it’s important for both partners to know their health status.
  • Many infections have no symptoms. Someone can have, and spread, an infection without knowing it.

Bacterial infections

These are the most common bacterial STIs. These are much easier to detect and treat in early stages. Without treatment, they can do a lot of damage and are harder to get rid of.

Trichomoniasis

This is really a parasite, but it’s treated with antibiotics. And, ladies, this is Grandma’s infection of choice, since women over 50 have the highest rates of infection.

How common is it?

Trichomoniasis has become the most common curable STI in the U.S. with about 3.7 million people infected. In one recent study, of those testing positive for trichomoniasis, 13 percent were women over 50; 11 percent were over 40. By contrast, 8.3 of women in their 20s tested positive. Based on these findings, researchers are recommending routine screening for sexually active women over 40.

How do you catch it?

Trich is passed from penis to vagina or vice versa. It doesn’t seem to infect other parts of the genitalia. Latex condoms help prevent infection.

What are the symptoms?

Seventy percent of women have no symptoms. Others may experience a greenish vaginal discharge, itching, inflammation, redness, or burning with urination in the month following the infection. Symptoms may come and go. The concern for older people with trich is that they are more susceptible to catching other STIs. It’s easily cured with antibiotics.

Chlamydia

How common is it?

Very. Rates of Chlamydia have more than doubled in the past decade, and it’s probably greatly under-reported. The U.S. Centers for Disease Control and Prevention (CDC) estimates that 2.8 million new cases occur annually.

How do you catch it?

Through oral, anal, or genital sex. Latex condoms are effective at prevention. Those with multiple sex partners should be tested regularly.

What are the symptoms?

Most women (70 to 80 percent) have none. The infection is particularly concerning for younger women, who are more susceptible to becoming infected and because, left untreated, it causes PID and infertility.

Chlamydia is easy to treat with antibiotics, but all partners must be treated to prevent reinfection.

Gonorrhea

How common is it?

The CDC estimates that about 700,000 cases of gonorrhea occur every year, although only about half are reported.

How do you catch it?

Gonorrhea is becoming known as a “super-bug,” one that’s very resistant to antibiotics. Because of this, doctors are advised to prescribe two kinds of antibiotics. It’s spread through contact with the penis, vagina, mouth, or anus of an infected person. The CDC says, “Latex condoms, when used consistently and correctly, can reduce the risk of transmission of gonorrhea.”

What are the symptoms?

Women tend to have very mild symptoms or none at all. Urination may be painful, or there may be vaginal discharge. Left untreated, the bacteria, which tends to flourish in the urethra, cervix, fallopian tubes, and uterus, can cause a massive internal infection called pelvic inflammatory disease (PID).

Syphillis

How common is it?

According to the CDC, there were 36,000 new cases of syphilis in 2006, and rates have held steady since, so this isn’t the most worrisome STI.

How do you catch it?

Through contact with the syphilis “chancre” or sore. These can be on the genitals, anus, vagina, or in the rectum. But they can also be on the mouth and lips. Condom use may not offer complete protection if the chancre isn’t covered by the condom.

What are the symptoms?

First stage: 10 to 90 days after contact, a hard, round, painless sore (chancre) appears where the bacteria entered the body, usually on the genitals. This heals by itself within a few weeks.

Second stage: A more extensive rash appears that may be brown or pinkish, often on the palms of the hands and bottom of the feet. It may be accompanied by flulike symptoms: fever, headache, weight loss. These, too, go away.

Last or latent stage: Without treatment, the disease may remain asymptomatic for 10 to 20 years, all the while the infection is slowly damaging internal organs and the neural system.

Syphilis is easy to treat with antibiotics in early stages. Later stages are very hard to treat.