STD Awareness: Trichomoniasis, the Pear-Shaped, Blood-Sucking, Silent Scourge

What’s shaped like a pear, hangs with a posse of bacteria, and is a silent scourge upon millions of urogenital tracts? I hope you guessed Trichomonas vaginalis, the single-celled parasite that causes trichomoniasis, or trich (pronounced “trick”). Trich is the most common curable sexually transmitted disease out there — currently afflicting around 3.7 million Americans and 156 million Earthlings.


These single-celled creatures pack a punch, but the body fights back.


When trich causes symptoms, sufferers might experience vaginal discharge (which sometimes has a bad odor), penile burning or discharge, spotting, and itching or swelling in the genital area. But around 70 percent of infections have no symptoms at all, making it a mostly “silent” disease. Based on the totality of the evidence, the Centers for Disease Control and Prevention (CDC) doesn’t currently recommend routine screening for trich in people without symptoms.

But it’s the subject of some debate. Since both symptoms and screenings are rare, and the disease isn’t reportable, some health experts worry that trich could be doing a lot of damage right under our noses. An infection during pregnancy could increase risk for preterm labor or low birth weight. It can increase risk for both acquiring and transmitting HIV from or to a partner. Women with trich are more likely to acquire an HIV infection when sexually exposed to the virus — in fact, one study estimated that 6.2 percent of all HIV infections among U.S. women could be attributed to trich. It’s also easier to catch HIV from a man with trich than from a man without trich. Continue reading

STD Awareness: Which STDs Are Resistant to Antibiotics?

You’ve probably heard of MRSA, which is pronounced “mersa” and stands for methicillin-resistant Staphylococcus aureus — a strain of bacteria that is resistant to methicillin, as well as pretty much every other antibiotic out there. MRSA is an example of evolution by natural selection — what didn’t kill its ancestors made them stronger, spawning a drug-resistant strain.


There are drug-resistant strains of gonorrhea, trichomoniasis, and syphilis.


Evolution is the force behind life’s diversity. Normally, diversity is a good thing — but when it comes to microbes that cause diseases like gonorrhea, trichomoniasis, and syphilis, these organisms’ ability to evolve new defenses against our antimicrobial drugs isn’t good for us.

STDs have plagued us for millennia, but it wasn’t until the 20th century that we finally developed antibiotics, which gave us a powerful tool against many of our most formidable sexually transmitted foes. Suddenly, scourges like gonorrhea and syphilis could be quickly and easily treated with a dose of penicillin.

Problem solved, right? Nope. Enter evolution by natural selection. Continue reading

STD Awareness: Will STDs Go Away on Their Own?

teensCan gonorrhea go away without treatment? Does chlamydia eventually clear up? Can trichomoniasis go away on its own? These are the kinds of questions people pose to Google before Google sends them here — at least that’s what I learned by looking at the blog’s stats. They’re tricky questions to tackle, and for so many reasons.

Some viral STDs stay with you for life, such as herpes and HIV. Others, such as hepatitis B and human papillomavirus (HPV), can be prevented with vaccines but cannot be cured. It’s also possible for the immune system to defeat hepatitis B virus and HPV — but in some cases, these viruses are able to settle in for the long haul, causing chronic infections that can endure for life and even lead to cancer.


Left untreated, syphilis can kill, and gonorrhea can cause infertility.


Non-viral STDs, like chlamydia and gonorrhea, can be cured. However, they usually don’t have symptoms, or symptoms can come and go, making it seem like an infection went away when it actually didn’t. You can’t know your STD status without getting tested, and you can’t self-diagnose an STD based on symptoms and then assume the infection went away when symptoms subside. Getting tested can uncover a problem and clear the way for treatment.

Nonetheless, people want to know if an STD can go away by itself — but there aren’t many studies on the “natural history” of curable STDs like gonorrhea, chlamydia, and trichomoniasis. Studying the natural course of a curable infection would require that scientists put their subjects at risk of the dangers of long-term infection, and no ethics board would approve such an experiment. Continue reading

STD Awareness: Is Bacterial Vaginosis a Sexually Transmitted Disease?

Not to scale: Gardnerella vaginalis under a microscope. Image: K.K. Jefferson/Virginia Commonwealth University

Gardnerella vaginalis under a microscope. Image: K.K. Jefferson/Virginia Commonwealth University

Bacterial vaginosis, or BV, is the most common vaginal infection among people 15 to 44 years of age. It’s caused by an overgrowth of harmful bacteria, such as Gardnerella vaginalis. A healthy vagina hosts thriving populations of Lactobacillus bacteria species, but when these “good” bacteria are crowded out by certain types of “bad” bacteria, the vaginal ecosystem can be shifted, causing BV.

There is a lot of confusion about BV. Is it a sexually transmitted disease (STD)? What are the symptoms? How can you avoid it?

All good questions. Let’s examine them one by one.

Is BV an STD?

The consensus seems to be that BV isn’t officially an STD, but even reliable sources have somewhat contradictory information. Planned Parenthood doesn’t list BV as an STD on their informational webpages. The Centers for Disease Control and Prevention (CDC) does include BV on their STD website, but also says that “BV is not considered an STD.”

On the other hand, the Office on Women’s Health says that “BV can … be caused by vaginal, oral, or anal sex” and that “you can get BV from male or female partners.” And there’s an entire chapter devoted to BV in the premier medical textbook on STDs, and its authors say that, while sexually inexperienced females can get BV, “the weight of evidence supports sexual transmission” of G. vaginalis, the bacteria species most famously implicated in BV infections.

The same webpage on which the CDC declared BV not to be an STD also says that it can be transferred between female sexual partners. Indeed, women who have sex with women have higher rates of BV. Since vaginal fluid could spread BV, partners can change condoms when a sex toy is passed from one to another, and use barriers like dental dams when engaging in cunnilingus (oral contact with the female genitalia) or rimming (oral contact with the anus).

What about heterosexual transmission? Continue reading

Is Douching Safe?

This vintage douche ad claims that its product is “safe to delicate tissues” and “non-poisonous.”

Douching is the practice of squirting a liquid, called a douche, into the vagina. Many people believe it helps keep the vagina clean and odor-free, and some are under the impression that it helps prevent pregnancy and sexually transmitted diseases. An estimated 25 percent of American women 15 to 44 years old douche regularly. But just because douching is widespread doesn’t mean it’s safe; indeed, there are two possible mechanisms by which douching might be harmful.

First, douching might alter the pH of the vagina, changing its ecosystem. You might not think of a vagina as an “ecosystem,” but the bacteria and other microscopic organisms that live there sure do — and altering their habitat can harm the beneficial microbes that live there, opening the door for disease-causing microbes to take over the territory. Frequent douching can result in the vagina’s normal microbial population having difficulty reestablishing its population.


Douching increases risk for infections and fertility problems, and has no proven medical benefits.


Second, a douche’s upward flow might give pathogens a “free ride” into the depths of the reproductive tract, granting them access to areas that might have been difficult for them to reach otherwise. In this manner, an infection might spread from the lower reproductive tract to the upper reproductive tract. Douching might be an even bigger risk for female adolescents, whose reproductive anatomy is not fully formed, leaving them more vulnerable to pathogens.

While douching is not guaranteed to harm you, there is no evidence that it is beneficial in any way. Establishing causation between douching and the problems that are associated with it is trickier — does douching cause these problems, or do people who douche also tend to engage in other behaviors that increase risk? So far, the best evidence indicates that douching is correlated with a number of diseases and other problems, including sexually transmitted diseases (STDs), bacterial vaginosis, pelvic inflammatory disease, fertility and pregnancy complications, and more. Continue reading

STD Awareness: Three Sexually Transmitted Bugs That Will Fascinate and Intrigue You

From creepy crawly pubic lice, which can be seen with a magnifying glass, to minuscule human papillomaviruses, which can be seen with some of the most expensive microscopes in the world, there are many tiny pathogens that we can acquire through sexual contact. And, despite their diminutive sizes, some of them work in complicated ways, or tell stories about our origins that would blow you away. Let’s learn some amazing facts about three sexually transmitted bugs!

Phthirus pubis, the louse that causes scabies. Image from the Public Health Image Library.

Image: Public Health Image Library

Pubic lice: tiny insects that live in pubic hair

Fans of Charles Darwin might like learning about pubic lice, which offer clues about human evolution. While other apes’ bodies are habitat to only one species of louse, human bodies can host three different types of louse: head lice and the closely related body lice, as well as the distantly related pubic lice.

It is thought that when early humans lost their body hair, human lice followed this receding hairline and migrated to their heads to become head lice. At a later date, the gorilla louse colonized early humans’ pubic regions. Since pubic lice can be transmitted by infested bedding, one idea is that an early human caught pubic lice by sleeping in a burrow that had been recently vacated by a lice-ridden gorilla — no sexual contact required.

By examining the number of differences in the genetic codes of the modern gorilla louse and the human pubic louse, we can place their divergence into two separate species at about 3 million years ago, suggesting that our human ancestors lost their body hair at around that time.

A quite frankly weird fact about pubic lice involves the method their young use to hatch from their eggs — by releasing so much gas that the increase in air pressure causes them to burst from their shell. So there’s that. Continue reading

STD Awareness: Do Sexually Transmitted Diseases Increase HIV Risk?

virion HIVYou might have heard that having an STD like syphilis, herpes, or gonorrhea can make it easier to catch HIV, the virus that causes AIDS. But have you ever wondered if this was true? Maybe it’s just a simple correlation — for example, someone who doesn’t practice safer sex would be more likely to catch HIV along with any other STD. That doesn’t mean that one causes the other, does it?


Common STDs like herpes and trichomoniasis can increase HIV risk.


But it’s not a mere correlation. If you take one person with an STD and one person without an STD and expose them both to HIV through sexual contact, the person with the STD will be at least two to five times more likely to become infected with HIV. Why is that? First, many STDs can make you more susceptible to an HIV infection. Second, the immune response triggered by many sexually transmitted infections can summon the types of immune cells that HIV targets.

Furthermore, if a person with HIV is co-infected with another STD, he or she is more likely to transmit HIV to a partner. In other words, STDs can make a person with HIV more infectious. HIV is more likely to appear in their genital secretions, making it easier to transmit HIV through sexual activity. Continue reading