STD Awareness: New STDs on the Block, and STDs Making a Comeback

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. Continue reading

STD Awareness: Chlamydia trachomatis

A colony of C. trachomatis (colored green) is nestled inside a human cell. Image: V. Brinkmann, Max Planck Institute for Infection Biology

A colony of C. trachomatis (colored green) is nestled inside a human cell. Image: V. Brinkmann, Max Planck Institute for Infection Biology

In the microscopic world of germs, organisms called Chlamydiae are dwarfed by their fellow bacteria. An E. coli bacterium can hang out with 100,000 of its closest friends on the head of a pin, but Chlamydiae are smaller still. Infectious particles are about one-tenth the length of an E. coli, rivaling the size of a large virus. And, just like a virus, Chlamydiae can still pack quite a punch, proving that sometimes, not-so-good things can come in small packages.

There are many types of Chlamydiae bacteria, but one species, Chlamydia trachomatis, is responsible for not one, but two sexually transmitted diseases (STDs) in humans: chlamydia and lymphogranuloma venereum (LGV). (Humans aren’t the only ones affected by sexually transmitted Chlamydiae. A different species, Chlamydia pecorum, is devastating wild koalas in Australia, which has got to be one of the biggest bummers ever.)


Chlamydia is a case study for the importance of safer sex and regular STD testing.


Chlamydia is one of the most common STDs in the United States — there were almost 1.5 million diagnoses in 2011 alone, but experts estimate that there were around another 1.5 million cases of chlamydia that went undiagnosed. How can this be? Chlamydia is often a “silent” infection, meaning that symptoms are rare, allowing people to harbor these bacteria without even knowing it. (When symptoms do occur, they might include swelling in the genital region; vaginal, cervical, or penile discharge; or painful urination.)

It might seem like a small mercy that this common infection is unlikely to torture us with harrowing symptoms — but, in actuality, those of us who have to deal with discharge or burning urination should try to appreciate the heads up: Left untreated, chlamydia can cause serious complications. When it spreads along the female reproductive tract, it can cause pelvic inflammatory disease, which can severely compromise fertility and cause chronic pain. Rarely, in a male reproductive tract, it can cause epididymitis, which can also spell bad news for future fertility. Continue reading

STD Awareness: 10 Sexually Transmitted Diseases You Probably Don’t Know About

Giardia lamblia, a microbe that can be transmitted sexually. Image: NIH

Gonorrhea and chlamydia go back to antiquity. Syphilis took hold in Europe during the late 15th century. Herpes wasn’t on most people’s radars until the early 1980s, and human papillomavirus (HPV) was relegated to relative obscurity in the popular imagination until the HPV vaccines made their debuts less than a decade ago.


Have you heard of CMV, chancroid, or donovanosis?


But there are still a handful of sexually transmitted diseases (STDs) that you might not know about. These include incredibly common infections, as well as those caused by pathogens you might have heard of but probably don’t associate with sexual transmission. They also include infections that are very rare here in Arizona but are much more common in other parts of the world. They all deserve a closer look.

10 Trichomoniasis: What is the most common curable STD? You might guess that it’s chlamydia or gonorrhea, but according to the Centers for Disease Control and Prevention, it’s trichomoniasis (also known as trich, pronounced “trick”). This infection is caused by Trichomonas vaginalis, a single-celled parasite that is actually pretty cute as far as microbes go. What’s not so cute is its propensity to attach to your cells and degrade their surfaces, which on a large scale can produce unpleasant symptoms. Continue reading