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About 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.

STD Awareness: The Vaginal Microbiome and Cervical Cancer

Cervical cancer is caused by human papillomavirus (HPV), which has been nicknamed “the common cold of STDs” — because pretty much every sexually active person will get it at some point. Luckily, that scary stat is poised to change as more people receive the HPV vaccination, which protects against nine major strains of the virus.

HPV jumps easily from person to person, spread by pretty much all types of sexual contact. For most people, the infection clears up within 8 to 13 months, but sometimes the infection develops into a chronic condition, which increases risk for certain cancers — including cervical cancer, but also cancers of the anus, genitals, and throat. Unfortunately, it’s hard to predict if your immune system will vanquish your infection, or if you’ll develop a chronic infection.

Members of the lactobacilli family, keeping vaginas healthy across the globe. Image: Josef Reischig

Luckily, the vagina has some tricks up its sleeve to protect itself from HPV, and some of its best weapons are bacteria. Yep — a healthy vagina isn’t germ-free. To the contrary, it needs lactobacilli and other beneficial microbes to maintain a healthy environment. Bacteria from the Lactobacillus genus produce lactic acid and other chemicals, which help keep dangerous bugs away. Vaginal environments in which Lactobacillus gasseri dominate, for example, are more likely to clear HPV infections. L. crispatus helps trap HIV in a thick mucus, reducing infection risk. Other lactobacilli species secrete chemicals that ward off yeast infections. Sometimes, however, good bacteria lose this turf war, and “bad guys” move in.


The population of microbes that live in your vagina are known collectively as the vaginal microbiome.


University of Arizona researchers in Phoenix performed a “census” of the vaginal microbial communities of 100 premenopausal women. They learned that women who have cervical cancer or precancerous abnormalities have drastically different vaginal microbiomes. Healthy vaginas were generally dominated by lactobacilli, but as cervical health declined, their populations declined, and “bad” bacteria took over. One such bad guy, called Sneathia, was linked to HPV infection, precancer, and cervical cancer.

Which Came First?

Finding a new vaginal “bad guy” was exciting, and Sneathia had previously been linked to other gynecological problems, ranging from bacterial vaginosis to pregnancy complications. But the researchers were looking at a snapshot in time — they didn’t know what came first, the Sneathia or the cervical abnormalities. Were lactobacilli protecting the cervix whereas Sneathia were harming it, or did a chronic HPV infection set the stage for Sneathia to move in and thrive? It’s a real “chicken-and-egg” conundrum. Continue reading

Katharine Dexter McCormick: Fierce Feminist and Secret Smuggler

Katharine Dexter McCormick was born into a life of wealth and privilege — and progressive politics. The family home in which she was born in 1875 had once been a stop on the Underground Railroad. Her parents encouraged her education, and she was among the first women to attend the Massachusetts Institute of Technology, and, in 1904, one of its first female graduates, having earned a bachelor’s degree in biology.


Katharine McCormick harnessed stereotypes about wealthy women to hide subversive acts of civil disobedience in plain sight.


Katharine wanted to be a doctor, but in 1904 she married Stanley McCormick, a Princeton-educated man and heir to a vast fortune. Her oath to stay by his side in sickness and in health, until death did them part, was tested just two years into their marriage, when Stanley’s mental health had deteriorated to the point that he was institutionalized. He was diagnosed with what today is called schizophrenia, and his family sent him to their mansion outside Santa Barbara, a “gilded cage” run by an all-male staff of doctors and nurses who provided round-the-clock care.

The all-male staff was necessary, as Stanley had developed violent tendencies that seemed to be directed primarily toward women. Katharine went nearly two decades without any physical contact with her husband — though she could write letters, talk to him on the phone, or crouch in the bushes and watch him through binoculars. Katharine stayed married to him until his death in 1947. The entire time, she was heavily involved in directing his care — despite constant clashes with his family — and remained optimistic for a cure.

But outside of her marriage, Katharine cultivated a rich life, devoting herself to women’s rights and becoming a high-ranking leader in the fight for the right to vote. After women’s suffrage was won, she was eager to turn her attention to the next fight — and was invigorated by the energy of the birth control movement, which, like the suffrage movement before it, drew ire and outrage from both church and state. Continue reading

STD Awareness: Winning One War on Cancer

Cancer starts with the uncontrolled division of cells.

The developed world is in the midst of a huge nosedive in genital warts and cervical “precancer” — all thanks to the human papillomavirus (HPV) vaccine. This simple shot trains the immune system to defend itself against HPV, a virus that causes genital warts and several types of cancer. Most sexually active people will be exposed to it in their lifetimes — it’s even been nicknamed the “common cold” of sexually transmitted infections.

Gardasil 9 protects against seven strains of HPV that collectively cause 90% of cervical cancers and anal cancers, plus the two HPV strains that are jointly responsible for 90% of genital warts. Vaccination also reduces the frequency of “precancers,” which are cellular abnormalities that can be treated before progressing into full-fledged cancer — meaning less time, money, and anxiety spent dealing with follow-up procedures and treatments.


The HPV vaccine is an anti-cancer vaccine.


The vaccine is safe and effective — and when we say “effective,” we mean it could lead to the eradication of HPV, and with it the cancers it causes. A recent analysis of 66 million vaccine recipients published in The Lancet points to plummeting rates of genital warts and precancer. Among teenage girls, there was an 83% drop in HPV-16 and HPV-18 infections (the two strains of HPV that together cause 70% of cervical cancers) — and cervical precancers were cut in half.

The most dramatic gains were made in countries that offered the HPV vaccine to both boys and girls. Additionally, there were even decreases in the HPV strains that aren’t covered by the vaccine — evidence of “cross-protection,” the phenomenon in which the immune system recognizes close relatives of the viruses it has been trained to attack. Even people who did not receive the vaccine were less likely to catch the virus, simply because their risk was reduced if their partners were vaccinated. Continue reading

STD Awareness: Can I Get Gonorrhea from Kissing?

Not all types of kissing feature the exchange of saliva.

Some pretty depressing news hit a couple of months ago, when headlines proclaimed kissing could allow gonorrhea to jump from one person to another.

We already knew gonorrhea could be transmitted during oral sex — a terrible fact, given that most people don’t use condoms or dental dams during oral sex. And we knew that oral gonorrhea is more likely to develop drug resistance, which could be helping to drive the possibly untreatable gonorrhea of the near future.


Mouth-to-mouth kissing could be transmitting gonorrhea right under our noses — literally.


Gonorrhea is most famous as an infection of the cervix or the urethra. But the bacteria that cause gonorrhea can thrive in other warm, moist areas of your body — not just the reproductive tract, but also in the mouth, throat, eyes, and anus. Unprotected oral sex can allow those bacteria to travel in either direction between one person’s genitals and another person’s throat.

But what about mouth-to-mouth kissing, like French kissing? Is that enough to allow these bacteria to hitch a ride from one mouth to another? Previous research, using a mathematical model, estimated that mouth-to-mouth contact might be a significant — and underappreciated — mode of gonorrhea transmission. But that was a mathematical model, a sophisticated equation using what we know about a population’s gonorrhea prevalence and sexual behavior to estimate how frequently the infection is transmitted from one mouth to another. Continue reading

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: Searching for an HIV Vaccine

Ever since the dawn of the AIDS era, researchers have worked nonstop to develop an HIV vaccine. In 1984, Margaret Heckler of the U.S. Department of Health and Human Services famously (over)promised that a vaccine would be ready for testing in two years. But it’s taken much, much longer. This Saturday, May 18, is HIV Vaccine Awareness Day, a celebration of the patients, community members, and scientists who are hard at work bringing this vaccine into existence.


Only one vaccine — still in the experimental stage — has shown any effectiveness against HIV.


Hiding from the Immune System

Vaccines are inspired by our own bodies’ ability to fight disease. Usually, when our immune system encounters a threat, it takes note of the viral “antigens,” which are like facial features — a button nose, say, or dramatically arched eyebrows — that make it instantly recognizable. It creates “antibodies,” weapons that can target those antigens like guided missiles. Often, the immune system can remember the distinguishing facial features so it’s ready to attack if the enemy ever returns — giving us immunity, possibly for life.

Vaccines take advantage of our natural ability to create these immune memories by exposing our immune systems to antigens without actually exposing us to infectious viruses. Think of it as a “wanted” poster that helps the immune system recognize “bad guys” before it actually sees them on the street, enabling it to attack and destroy them before they cause disease. Continue reading

Enjoying the Condom of Today While Waiting for the Condom of the Future

When the “consent condom” was introduced last month, it made a minor media splash. The developers of this new condom, packaged in a box that required four hands to open, sought to place the concept of consent at the center of all sexual interactions.

Almost as soon as it grabbed its first headlines, however, the consent condom attracted criticism from multiple sources. Is consent an ongoing dialogue rather than a one-time agreement? Can’t consent be revoked? Do these condoms marginalize people with disabilities that preclude them from opening the box? Couldn’t a rapist force a victim to help open the box, or enlist the assistance of an accomplice? Could they be used as misleading evidence against claims of sexual assault?


With STD rates skyrocketing, more people need to learn how to get the most from condoms — the most protection, the most comfort, and the most pleasure.


Despite the negative reaction, the fact remains that the consent condom succeeded in one goal: provoking public dialogue about the complexity and primacy of consent. It isn’t likely to be a commercial success: Even if a few are sold as novelties, a condom that comes with built-in obstacles doesn’t seem destined for popularity. After all, if regular condoms were too tricky for the inept baby boomers on Seinfeld to master, a complicated gadget requiring four coordinated hands to spring loose probably isn’t going to be a breeze for millennials.

Continue reading