How Sex Works

by Dr. Sharon Moalem

  Earlier this year, I got to see first-hand the devastation that an untreated HPV infection can cause. A patient was admitted to a New York City hospital because of an abscess in his groin that was a little larger than a tennis ball. Unfortunately for him, the abscess was the least of his problems. He had a pretty advanced form of penile cancer that spread to his groin, causing the abscess. Most of the head of his penis (called the glans) had been overtaken by cauliflower-like warts. Much of his penis had to be removed through an amputation procedure called a penectomy. Unfortunately for this patient, although he was still young, he has a less than 50 percent chance to live another five years.

  AS WE DISCUSSED in Chapter 2, HPV has also been at the center of one of the biggest breakthroughs in cancer treatment we’ve seen. Like most viruses, HPV comes in many different strains—more than one hundred have been identified so far. Last year, the Food and Drug Administration gave its approval to a vaccine that prevents infection from four of the most common strains—HPV types 6, 11, 16, and 18. Two of these, types 16 and 18, are thought to be responsible for around 70 percent of all cervical cancer, whereas types 6 and 11 cause and 90 percent of genital warts. The medical community now recommends vaccination against HPV for all girls starting at eleven or twelve years of age, although the vaccine can be administered to girls as young as nine. So far the FDA has only approved the vaccine for women up to age twenty-six, although some doctors have been giving it off-label to older women. The key to successful protection is vaccination before a girl’s first sexual contact. And sexual contact means exactly that—contact, not intercourse.

  Like many STIs, including herpes, gonorrhea, syphilis, chlamydia, HPV can also be transmitted through oral sex. In fact, oral cancer—cancer of the tongue, mouth, and throat—caused by HPV has climbed sharply over the last three decades, and scientists link the climb to increased oral sex, which means oral contact with a sexual partner’s penis, vulva, vagina, or anus.

  A team of researchers at Johns Hopkins University in Baltimore, Maryland, studied forty-six thousand cases of oral cancer from the last thirty years. They report that oral cancers linked to HPV climbed by more than 30 percent from 1973 to 2004, even as oral cancers unrelated to HPV have dropped since 1982, probably due to a drop in other risk factors like smoking, chewing tobacco and drinking alcohol, according to the researchers. The sharpest rise in oral cancer was among young white males. This makes sense to other experts, like Lesley Walker, the director of cancer information at Cancer Research UK: “What we do know is that the prevalence of HPV is high, particularly among young people,” says Walker, “and this shouldn’t be a surprise given that, since the sexual revolution, people have been having more sexual partners.”

  “We need to start having a discussion about those cancers other than cervical cancer that may be affected in a positive way by the vaccine,” says Dr. Maura Gillison, who heads up the Johns Hopkins research team. She believes there’s a strong argument to be made for vaccinating young boys as well as young girls against HPV.

  Not everyone is so sure. Walker thinks more research is necessary to ensure that it would actually make a significant dent in the incidence of male oral cancer in order to justify the high cost of vaccinating so many boys. Still, there are many who argue it’s a good idea, and not only because of oral cancer. Cervical cancer is so deadly to women that some believe it makes sense to prevent as much HPV infection as possible, and that means vaccinating boys too. Obviously, if a man has been vaccinated against HPV and can’t become infected, then he can’t infect other woman (or men, since there is an association between rectal cancer and HPV), whether or not they’ve been vaccinated.

  THE MOST COMMONLY reported bacterial STI in the United States today is called Chlamydia trachomatis. Somewhere in the neighborhood of 1 million cases of chlamydia are logged every year. It’s especially common in sexually active adolescent girls and African American women between the ages of eighteen and twenty-six. And a recent study suggests that sexually active college freshmen of both sexes may be especially at risk.

  Chlamydia is a particularly sneaky infection because it very often doesn’t cause any symptoms; about half of infected men and 80 percent of infected women are asymptomatic. The microbe itself is hard for our immune system to find and kill because it typically resides inside human cells, whereas our immune system has an easier time dealing with entities outside of our cells. When it does cause symptoms in both men and women, it makes it painful to urinate. For some men, there can be a small discharge or a swelling of the testicles as well. Making matters even trickier, until recently, the best way to diagnose chlamydia in men was by examining scrapings of epithelial cells from the man’s urethra. This involved inserting a Q-Tip–like probe into a man’s urethra through the head of his penis. As you can imagine, this made some men reluctant to be tested. Thankfully, there are newer and much more comfortable ways, such as a urine test, to detect chlamydia today.

  The symptoms of an infection aren’t the most significant threat posed by the disease—it’s the silent damage to fertility that makes chlamydia such a problem. In women, chlamydia can cause tubal factor infertility, scarring the Fallopian tubes or even blocking them entirely, making it difficult or impossible for sperm and eggs to meet. For a long time, doctors and scientists thought chlamydia only posed a threat to female fertility, but new research shows there’s a real risk to men too. Two studies have found a significant link between chlamydia and male infertility.

  In 2004, a team of scientists led by Professor Jan Olofsson of Umeå University Hospital in Sweden published a report in the journal Human Reproduction that found a correlation (remember, this does not mean causation) between fertility trouble and chlamydia infection in men. Olofsson and his team tracked 238 couples getting help for fertility problems from 1997 to 2001. They found that men infected with chlamydia were about one-third less likely to become fathers than men who were not infected.

  In 2007 José Luis Fernández of the Juan Canalejo University Hospital in Corunna, Spain, and his colleagues presented a report to the American Society for Reproductive Medicine that helped explain the connection between chlamydia and male infertility. Fernández and his team found that chlamydia seems to cause severe genetic damage to the sperm of infected men. When they compared the genetic health of sperm in infected and uninfected men, they found that 35 percent of the sperm from infected men had fragmented DNA, compared to only 11 percent in the uninfected men. The good news is that treatment with antibiotics not only cured the men of chlamydia; it helped to restore their sperm to a healthy state.

  Besides infecting the reproductive system, chlamydia loves to get into people’s eyes. Once there it causes conjunctivitis, which in its chronic form becomes trachoma, probably the leading cause of blindness in the world. In some parts of the world, these types of chlamydial infections are actually spread by flies. But the surest way for children to become infected is from their mothers.

  HERPES SIMPLEX IS actually two related DNA-type viruses—herpes simplex virus 1, or HSV-1, and herpes simplex virus 2, or HSV-2. Herpes infections were once segregated by the physical site of infection. The two most common types being oral and genital herpes.

  HSV-1 is commonly thought to be the virus that causes oral herpes and HSV-2 the virus that causes genital herpes, but that’s not totally correct. As a real estate agent might say, it’s location, location, location. Either virus can infect above the waist or below it. In fact, HSV-1 infections of the genitals have been steadily rising, perhaps in part because of increased rates of oral sex.

  Herpes is a neurotrophic virus; it loves to make its home in the nervous system. Interestingly, it’s thought that humans are the only animals “hospitable” enough to give herpes a home.

  In the United States, the number of people with antibodies to HSV-1 is as high as 80 percent. When the immune system encounters an infecting agent like a virus, it produces specific proteins, called antibodies, that help fight the specific infecti
on. Hence, the presence of antibodies indicates past exposure. Prevalence increases with age across the board, but there are differences among socioeconomic groups. By age thirty, for example, half of the people in upper socioeconomic groups have antibodies to HSV-1, compared to 80 percent of people in lower socioeconomic groups. Lower socioeconomic groups tend to bear a higher load of diseases in general, partly, it is thought, because of less access to proper diet and health care.

  A little over 1 million new cases of genital herpes are diagnosed every year, and more than 50 million people—around one in four adults—are thought to be currently infected in the U.S. If that doesn’t seem to add up, it’s because herpes never goes away. Once people are infected with herpes, they are thought to be infected for life, although they don’t always have symptoms and they’re not always contagious.

  Both oral and genital herpes (regardless of the subtype of virus that caused them) manifest symptomatically as lesions or blisters filled with the virus. Oral herpes appears on the lips, tongue, cheeks, and gums. Sores from genital herpes can break out on the penis, the vulva, the anus, and even the inner thighs and buttocks. In healthy people, the sores usually resolve and heal within a few weeks. At this point the virus migrates back into nearby nerve tissue, where it resides without causing symptoms. Herpes cycles between two stages: the latent stage, or remission, and the symptomatic stage, known as active disease. This period of latency is one of the many evolutionary strategies that some microbes employ to escape detection by our immune systems and wait for opportunities to infect others.

  During phases of active disease, herpes is highly contagious, and contact with infected sores should absolutely be avoided. One of the tricky things about genital herpes, though, is that it can also be contagious even when the person is asymptomatic. The virus can still shed infectious copies of itself, even without causing symptoms. Some people, probably because of genetic background or strong immune responses (possibly a combination of both) can be infected with herpes and never actively express any symptoms, although, as just mentioned, they can still be contagious. Others have multiple recurrences per year. People infected with either subtype of herpes, and their partners, should use condoms and dental dams (a piece of latex you place over the vulva or anus) to prevent transmitting the virus. We don’t know exactly what causes recurrences, but stress, exposure to sunlight, having another (different) infection, and even menstruation have all been identified as potentiating factors. It’s almost as if the virus waits for the most opportune time when the immune system is somewhat compromised to mount an attack.

  Herpes doesn’t infect just the oral or genital regions; it comes in other varieties too. Herpes whitlow is a very painful infection of the fingers or toes that is most often contracted by health-care workers exposed to the virus, especially by dental workers who encounter oral herpes. It is characterized by the emergence of small, blisterlike sores that merge as they swell and cloud. The sores typically last two to three weeks. Herpes can also infect the eye; it’s then called ocular herpes or herpes keratitis. There’s even a version called herpes gladiatorum, wrestler’s herpes, or mat herpes, which affects people in contact sports. When scrapes, cuts, or mat burns on the skin come into contact with the herpes virus, an individual can become infected and suffer sores at the site of infection.

  And herpes simplex encephalitis, or HSE, is an infection of the brain and nervous system. Exactly how herpes travels through the nervous system to gain access to the brain isn’t fully understood, but the effects and danger posed by HSE are well known. Untreated, HSE is fatal in more than two-thirds of cases; even treated, it kills about one in five, and it can leave those infected with some form of brain damage.

  One of the very rare effects of herpes encephalitis is at once disturbing and intriguing. Damage from herpes (or other trauma) to a part of the brain called the amygdala, which is thought to be responsible for emotional learning, can produce a rare, yet sometimes reversible, neurological disorder called Klüver-Bucy syndrome.

  People with Klüver-Bucy syndrome routinely explore objects with their mouths (which is a great way for the virus to spread), much like an infant or toddler. And they often become hypersexual, displaying very inappropriate sexual behavior. About a third of HSE infections are in children under the age of eighteen. When infection results in Klüver-Bucy syndrome, the symptoms of hypersexuality can be troubling to observe.

  I believe the virus’s attack on the amygdala is no evolutionary accident. As I wrote about at length in Survival of the Sickest, there is clear evidence throughout nature of pathogens affecting the behavior of their hosts in a way that facilitates their transmission. In the rare case of Klüver-Bucy, the hypersexuality that can result may be quite extreme.

  New York psychiatrist Laurence Tancredi explains that the behavior patterns we consider aberrant may sometimes have biological drivers. “In children, [Klüver-Bucy syndrome] may be manifested by intermittent thrusting of the pelvis, holding of one’s genitals, or rubbing the genitals in a masturbatory movement on the bed,” writes Tancredi in his book Hardwired Behavior. What better way for a sexually transmitted infection to improve its chances of infecting new hosts than to push its host toward promiscuity by triggering hypersexuality?

  Klüver-Bucy syndrome is exceptionally rare, and, thankfully, these behaviors seem to subside on their own over time. What is interesting and still unclear is whether the virus that causes herpes can cause subtle behavior changes without causing full-blown encephalitis.

  The truth is, in most people with healthy immune systems, herpes can be terribly unpleasant, but it’s very rarely life-threatening. But it’s very important to be aware if you’re infected, especially if you’re pregnant. Herpes can be transmitted to newborns during delivery, which is thought to happen as frequently as once in every 2,500 live births in the United States. In newborns, a herpes infection is very dangerous. Death from neonatal herpes can be as high as 60 percent of those infected. If a woman has a primary infection of genital herpes—that is, she is symptomatic or asymptomatic but still shedding virus at the time of her initial infection—there is a 50 percent chance that her new baby will contract herpes while he or she is being delivered, if the delivery is vaginal. The risk can be reduced by a cesarean delivery, which is why it is so important to tell your doctor if you’re pregnant and think you might have herpes. If you’re having sex with a pregnant woman and think you might have herpes, tell your partner. The key thing here is to remember that symptoms don’t matter—if you’ve ever had herpes, you always will have herpes and need to use that information to protect yourself and others, especially when it comes to the future health of newborns.

  There’s no real cure for herpes so far, although there are a few antiviral medications on the market that seem to shorten the length of outbreaks of active disease. If you’re one of those unlucky people who have multiple recurrences per year, you should know that there are also antiviral regimens that can help reduce recurrences.

  There may be other options too. A few studies have shown that increasing the ratio of lysine to arginine, both amino acids that you consume (either through the diet or with supplements), may help to reduce the severity and length of outbreaks. Lysine, in higher relative concentrations to arginine is found in certain foods such as red meats and dairy products; higher levels of arginine is found in wheat, many kinds of nuts, and fruits. The easiest way to increase the ratio of lysine to arginine may be to take lysine supplements, but you should talk to your doctor before doing so. Some animal studies have shown that lysine may increase your cholesterol and triglycerides (high levels of which, like cholesterol, have been shown to contribute to arteriosclerosis, the hardening of the arteries that can cause heart disease).

  Even more promising, there is hope of a herpes vaccine on the research horizon. Studies have shown that an experimental vaccine provided about 73 percent protection in women who had never been infected before. That’s certainly not perfect—and it doesn’t w
ork at all in men—but it’s a start.

  GONORRHEA, CAUSED BY a bacterium called Neisseria gonorrhoeae, is one STI that has actually been declining over the last twenty years, at least in the United States. But for anyone who does get infected, it’s a serious concern. The highest rates of new infections are in young women between the ages of fifteen and nineteen.

  Gonorrhea is another STI that can often remain hidden as its symptoms can be hard to spot or may not manifest at all. In men, the acute infection tends to become symptomatic two to seven days after infection. Symptoms can include pain during urination and discharge of a puslike substance sometimes called gleet. Less than half of women experience symptoms; when they do, there’s often discharge. Even with discharge, these symptoms are often missed or confused with yeast infections. And, like other stealthy STIs, untreated gonorrhea can lead to some serious complications, including pelvic inflammatory disease in some 10 to 20 percent of cases, and also cause infertility in women. Gonorrhea can also lead to septic arthritis, which occurs when bacteria migrate to joints and cause painful swelling and damage. Gonorrhea can also be spread through oral sex, infecting the throat, called pharyngeal gonorrhea, and anal sex, called rectal gonorrhea.

  Like other bacterial infections, gonorrhea is treated with antibiotics. Since co-infection with chlamydia is so common, antibiotics are usually given to treat both at the same time. And, like other bacteria commonly treated with antibiotics, gonorrhea has evolved antibiotic-resistant strains. The common antibiotic tetracycline is now essentially ineffective against gonorrhea, and ciprofloxacin-resistant strains are now common as well.

  The slang name for gonorrhea is “the clap.” There are a few theories about the origin of the term. The first, and most unpleasant to imagine, is that someone would “clap” the penis on both sides to clear the urethra of pus. Its origin may stem from the obsolete French word clapoir, which means “bubo,” a swollen lymph node as one might experience from infection with gonorrhea (or the bubonic plague). It may also be related to another old French word, clapier, which means brothel. Or maybe it was just a combination of the two; people called it the clap because they had a clapoir associated with too many visits to the clapier.