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Lately, a lot of us have had tunnel vision when it comes to infectious diseases. We talk about how long the virus that causes COVID-19 can live on various surfaces, even though other viruses can live on those same surfaces for even longer. We wonder if it can be sexually transmitted, while there are dozens of other bugs out there that are even more easily passed through sexual contact. There are more microbes out there than just the one that causes COVID-19, and we need to be mindful of their risks, too.

Last month, the New England Journal of Medicine published a piece about “old-timey” STDs that are making a comeback (think shigellosis), newer STDs to hit the scene (think Zika virus), and “classic” STDs that are finding new ways to harm us (think antibiotic-resistant gonorrhea). Let’s meet this rogues’ gallery of sexually transmitted bugs.

Shigella bacteria. Image: CDC

Shigellosis is a diarrheal disease caused by Shigella species of bacteria, which can be found in abundance in feces — making it relatively easy to pick up these bugs during sexual encounters involving oral-anal contact (“rimming” or anilingus). While Shigella are mostly transmitted through nonsexual routes, researchers have discovered that sexually transmitted shigellosis is much more likely to be resistant to multiple antibiotics — making them a serious threat.

Reduce your risk by practicing good hand hygiene and keeping a clean kitchen and bathroom; using condoms and dental dams during sex.

Hepatitis A virus. Image: CDC

Hepatitis A virus causes a short-term infection of the liver. Most people recover completely, though the illness can last from several weeks to several months. This virus is usually a food-borne bug, but it can also be spread by oral-anal sexual contact. The good news is there is a vaccine that protects you against hepatitis A virus.

Reduce your risk by practicing good hand hygiene and keeping a clean kitchen and bathroom; using condoms and dental dams during sex; getting vaccinated for hepatitis A.

Neisseria meningitidis

Neisseria meningitidis, a close relative of the bug that causes gonorrhea, causes meningitis, an inflammation of the protective membranes covering the brain and spine. There have been outbreaks of invasive meningococcal disease among MSM — men who have sex with men — though it’s not known exactly how it’s been spreading. Plus, like its cousin Neisseria gonorrhoeaeN. meningitidis can also cause urethritis, inflammation of the urethra characterized by discharge and a burning sensation while urinating. Strangely, the N. meningitidis bugs that cause urethritis have undergone a mutation that makes them look and act more like N. gonorrhoeaeThe bug usually lives in the nose and throat, but it can jump from the mouth to other body parts during sexual contact.

Reduce your risk by using condoms and dental dams during sex, including oral sex.

Mycoplasma genitalium. Image: American Society for Microbiology

Mycoycoycoplasma genitalium can cause urethritis in the male population, in which it’s responsible for 30% of persistent or recurrent urethritis, making it more common than gonorrhea but not as common as chlamydia. In women, M. genitalium has been found to wreak havoc on the reproductive system, where it is associated with cervicitis, or inflammation of the cervixpelvic inflammatory disease, which can lead to infertility, chronic pelvic pain, and increased risk for ectopic pregnancypreterm birth and miscarriage. We’ve known about this bug since the ’80s, but it’s already evolving antibiotic resistance, and it was only last year that the FDA approved a test for it.

Reduce your risk by using condoms and dental dams during sex.

C. trachomatis inside a human cell. Image: Max Planck Institute for Infection Biology

Lymphogranuloma venereum is caused by certain strains of Chlamydia trachomatis, which is mostly known for separate strains that cause chlamydia. Untreated, lymphogranuloma venereum has three stages of infection, beginning with small lesions on the genitals, followed by buboes (an inflamed lymph gland), and ending with chronic inflammation, as well as other complications, including genital ulcers, fistulas, proctitis, and genital elephantiasis. Rectal infections can mimic inflammatory bowel disease — though about half of infections don’t have any symptoms at all.

Reduce your risk by using condoms and dental dams during sex.

Zika virus

Zika virus is usually transmitted by mosquito bites, but it can also be transmitted through sexual contact and can cross the placenta to harm a fetus. Male-to-femalefemale-to-male, and male-to-male sexual transmission have all been documented. Zika virus can find refuge from the immune system in the testicles, which are a difficult location for a virus to enter — but, by the same principle, entry is also difficult for immune cells. Any virus wily enough to wend its way into the testicles, therefore, can replicate in relative peace. And it seems that this lucky virus can persist in the testicles for at least six months and hitch a ride in semen to find new victims.

Reduce your risk by wearing mosquito repellent and practicing mosquito-control measures; using condoms and dental dams during sex.

Ebola virus can also persist in semen, even after apparent recovery from the disease. Reduce your risk by abstaining from sex or using condoms for three months, or longer if your semen still tests positive for the virus.

Treponema pallidum

Syphilis, which had almost been driven to elimination in the United States at the turn of the century, is making a comeback, both among MSM and heterosexual women. In MSM, syphilis is associated with the use of PrEP, a lifesaving medication that lowers the risk for acquiring HIV — but might also lull people into a false sense of security, making them less likely to use condoms or seek STD screening.

Reduce your risk by using condoms and dental dams during sex, and knowing your partner’s status.

Congenital syphilis occurs when a baby is born with syphilis after being infected in the womb. As many as 40% of babies infected with syphilis during pregnancy will be stillborn or will die soon after birth. Congenital syphilis can also cause bone deformities, blindness, and deafness. It is especially tragic because it’s almost completely preventable with adequate prenatal care and antibiotics. Incidence of congenital syphilis is growing across all regions of the country and across ethnic groups, though it’s striking the South and African-American mothers especially hard, illustrating the need to increase access to prenatal care for all expecting mothers.

Reduce your risk by using condoms and dental dams during sex, and getting adequate prenatal care if you’re pregnant.

Neisseria gonorrhoeae. Image: National Institute of Allergy and Infectious Disease

Antibiotic-resistant gonorrhea is here, with documented cases of gonorrhea resistant to the last drugs we use to cure it. Over the years, gonorrhea has evolved resistance to every drug we’ve thrown at it. The last line of defense we have is a one-two punch of a pair of antibiotics: azithromycin and ceftriaxone. But, as we’ve seen in recent years, the wily bacteria that cause gonorrhea are chipping away at them, too. Experts fear that soon, gonorrhea’s remarkable evolutionary abilities will throw us back into the “pre-antibiotic era,” when gonorrhea was incurable and responsible for most female infertility.

Reduce your risk by using condoms and dental dams during sex, including oral sex.

The best way for sexually active people to avoid STDs is to use condoms and dental dams consistently and correctly, be screened for STDs with their partners before initiating sexual activity, and limit sexual partners. Planned Parenthood health centers can diagnose and treat STDs.

Tags: health, STD symptoms, sexually transmitted infections, STIs, healthcare, STIawareness

Anna C.


Anna first volunteered for Planned Parenthood as a high school student in the 1990s. Since then, she has received a bachelor’s degree from UC Berkeley and a master's degree in epidemiology from the University of Arizona. As an ode to her fascination with microbes, she writes the monthly STD Awareness series, as well as other pieces focusing on health and medicine.