STD Awareness: The Curious Case of Chancroid

Haemophilus ducreyi arrange themselves in parallel rows, which researchers have called “railroad tracks,” “schools of fish,” and “fingerprints.” Image: Mike Miller, CDC

Earlier this year, I asked a room full of scientists and medical professionals to raise their hands if they’d ever heard of chancroid. Everyone sat there, motionless, confused by the odd syllables I had uttered — shan kroyd. If you’ve never heard of chancroid, you’re not alone.

Chancroid is a sexually transmitted disease (STD) brought to you by Haemophilus ducreyi, a type of bacteria that can pass through microscopic tears in the skin during sexual contact. When one partner is infected, there is a 1 in 3 chance the other will become infected. An infection can cause painful sores and swollen lymph nodes, most often in the genital region. About half of people with chancroid infections will experience “buboes,” or swollen lymph glands that might rupture. Before it could be cured with antibiotics, a persistent infection could cause permanent skin damage.


Humanity can make chancroid the first STD to go extinct.


One reason you probably haven’t heard of chancroid is that, in the developed world at least, it has mostly disappeared. In fact, researchers believe chancroid can be completely wiped off the planet — which would make it the first STD ever to be forced into extinction. How amazing would that be?

Chancroid has been hopping from loin to loin since at least the days of the ancient Greeks, and was common until the 20th century, when rates began to decline. Thanks to antibiotics, U.S. chancroid rates decreased 80-fold between 1947 and 1997, all but vanishing by the late 1950s. It was virtually unheard of until there was another spike in the 1980s, correlating with the crack epidemic. But, since 1987, cases have been steadily declining. Continue reading

STD Awareness: The Surprising Sexual Transmission of Non-STDs

What is a sexually transmitted disease, or STD? If someone catches their partner’s cold during sex, is that cold an STD? According to the Office on Women’s Health, an STD is “an infection passed from one person to another person through sexual contact.” Unless the cold was passed through sexual contact, rather than mouth-to-mouth contact, it would not be considered an STD. Others say that, for an infection to be considered an STD, its sexual transmission must make it significantly more common in the population. So, a disease like the common cold would probably be just as common even if people never had sex.


MRSA, meningitis, and the virus that causes pinkeye can be transmitted sexually.


However, there are some infections, such as hepatitis C or bacterial vaginosis, whose status as official STDs is controversial. While researchers argue with one another over where to draw the line between an STD and a non-STD, let’s take a look at some bacteria and viruses that can be transmitted sexually, even though they’re not officially categorized as “STDs.”

MRSA: Methicillin-Resistant Staphylococcus aureus

MRSA bursting out of a dead blood cell. Image: Frank DeLeo, NIAID

MRSA bursting out of a dead blood cell. Image: Frank DeLeo, NIAID

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 every antibiotic in the penicillin family, as well as others. S. aureus, or “staph” for short, is the same bacteria responsible for TSS, or toxic shock syndrome, which has most infamously been associated with the use of highly absorbent tampons. But mostly, staph is a common cause of skin infections, which could be deadly in the pre-antibiotic era, but these days usually don’t raise too many eyebrows.

Unfortunately, with the emergence of MRSA, which is difficult to treat with the usual drugs, we might once again have to worry about minor skin infections blossoming into life-threatening conditions. Additionally, MRSA has found a way to hop from person to person via sexual contact, and sexually transmitted MRSA has been documented in both heterosexual and MSM (men who have sex with men) populations. Untreated, it can lead to a form of gangrene in which tissue blackens as it dies. 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

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

STD Awareness: Antibiotic-Resistant Syphilis

Treponema pallidum under a microscope. Image: Dr. Edwin P. Ewing, Jr., CDC

The image to your right, with lively yellow splotches against a pale green background, is not a long-lost Jackson Pollack piece, and the dark squiggly lines aren’t strands of paint haphazardly splattered onto a canvas. In fact, those squiggly lines are magnified images of the spiral-shaped bacteria species Treponema pallidum. You might not have heard of T. pallidum, but you’ve probably heard of syphilis, the sexually transmitted disease (STD) that these bacteria cause. While syphilis isn’t as common as other STDs, like chlamydia and HPV, it’s still out there, and occasionally communities experience outbreaks. It’s always best for sexually active people to be screened for STDs and practice safer sex.


The evolution of syphilis strains that are resistant to certain antibiotics underscores the need to use antibiotics properly.


Syphilis can inflict serious long-term damage — in fact, before the introduction of antibiotics, syphilis was the worst STD out there! Known as the Great Pox when it descended upon Europe 500 years ago, it could cause large and painful boils. Eventually, natural selection led to T. pallidum’s evolution into a form with milder symptoms, which benefited the bacteria by enabling its less boil-ridden (and presumably more attractive) human hosts to spread it farther and wider. Nevertheless, the symptoms of syphilis, if present, still include infectious sores, and when the disease goes untreated, it can cause severe, possibly fatal, damage to the nervous system.

Back in the day, there were myriad inadequate “treatments” for syphilis, ranging from straight-up quackery to the use of partially effective but toxic chemicals such as mercury. But a century ago, in 1912, a new arsenic-based chemical called Neosalvarsan was hailed as a “magic bullet.” Unfortunately, this treatment took weeks or even more than a year to administer — and had dangerous side effects. Quack treatments continued to flourish, and it wasn’t until the widespread adoption of penicillin in the 1940s that an effective cure with few side effects was available.

But natural selection endures; in fact, by flooding T. pallidum’s habitat with certain antibiotics, we’ve created an environment that favors the organism’s evolution against us. While not as immediately threatening as antibiotic-resistant gonorrhea, syphilis has been quietly evolving resistance to some of the antibiotics we use to treat it. This underscores the importance of using antibiotics correctly and emphasizing safer-sex practices, such as using latex condoms during vaginal or anal intercourse and during oral contact with a penis. Continue reading

STD Awareness: “What Are the Symptoms of an STD?”

“I was treated for chlamydia, but my girlfriend feels fine, so she doesn’t need to get tested.”

“The only time I don’t use condoms is for oral sex, and everything’s been OK ‘down there,’ so getting tested for sexually transmitted diseases would be pointless.”

It’s important to be able to recognize the symptoms of a sexually transmitted disease (STD). Being savvy about symptoms can push you to get tested right away if you notice that something is amiss. However, being symptom-free can lull you into a false sense of security, especially if you’ve engaged in sexual activities that could have exposed you to an infectious agent. The fact of the matter is that many people with STDs have no symptoms at all. As they say, “The most common symptom of an STD is … no symptom.” Let’s take a look at some common STDs.


The most common symptom of an STD is no symptom.


Bacterial Infections

Bacterial STDs are curable with antibiotics. They include chlamydia, gonorrhea, and syphilis — all of which can be asymptomatic, and all of which can have severe complications when they are not treated in time.

Chlamydia: Around 3 million Americans are infected with chlamydia annually, and the infection is especially common among young people (less than 25 years of age). Chlamydia can infect the penis, vagina, cervix, anus, urethra, eye, or throat. You can be afflicted with a range of symptoms: pain or a burning feeling while urinating; vaginal, cervical, or penile discharge; swelling around the anus, testicles, or vagina; and more.

However, you’re much more likely not to experience any symptoms at all — most people with chlamydia are unaware they have it. Three out of four women with chlamydia have no symptoms, and half of men with chlamydia have no symptoms. Left untreated, chlamydia can become a serious health threat. Long-term complications might lead to fertility problems and arthritis. Continue reading

STD Awareness: Intestinal Parasites

Editor’s Note: If you’re wondering if there is a sexually transmitted disease (STD) that causes maggots, please see our new article, “Is There an STD That Causes Maggots?”

This colorized scanning electron micrograph shows Giardia lamblia reproducing asexually. Image: Stan Erlandsen, CDC’s Public Health Image Library.

This colorized scanning electron micrograph shows Giardia lamblia reproducing asexually. Image: Stan Erlandsen, CDC’s Public Health Image Library

Most sexually transmitted diseases are caused by bacteria or viruses, but some are caused by organisms that are classified as completely different lifeforms. Trichomoniasis, for example, is caused by a protozoan organism; protozoa occupy their own kingdom, separate from plants, animals, and bacteria. Intestinal parasites are often protozoan organisms, but can also include parasitic worms (which are members of the animal kingdom). They are spread through contact with fecal matter — and as such, they can be transmitted sexually as well as nonsexually. Intestinal parasites are usually transmitted by fecal contamination of food or water, and are most common in areas with insufficient sewage treatment and untreated water in the wilderness. Some pathogens, however, have low infectious doses, making their sexual transmission more likely.


What has eight flagella and can live in your intestines?


Oral contact with the anus, also called anilingus or rimming, is the primary means of the sexual transmission of these pathogens. Putting fingers or hands in your mouth after they have had contact with the anus is also risky. Other modes of transmission include oral sex, as genitals can be contaminated with feces, as well as sharing sex toys and other equipment. For these reasons, it is very important to use dental dams or latex gloves during contact with the anus; to clean the anus before engaging in rimming; to clean or use condoms on shared sex toys; and to use condoms or dental dams during oral sex. Continue reading