Sex can be so fabulous that sometimes members of the microscopic kingdoms—like bacteria and viruses—come along for the ride. As we’ve pointed out elsewhere, this makes them just like other diseases that pass from human to human, though when you get the flu from your lover you don’t usually call it a “sexually transmitted infection.” Many people are especially upset about STIs, but this may be associated with a long-standing social shame about them; most people learn this reaction with all the other attitudes about sex that they absorb well before adulthood.
Another issue is that to talk to people about STIs, you have to talk about sex, and the whole discussion can become politicized or fraught. It doesn’t have to be this way, and we’d just like to remind you that we would have way fewer STIs if we were able, in our families, sex education classes, relationships, and media, to discuss these conditions and their prevention in a calm and matter-of-fact way. We don’t say this to minimize STIs—it’s way better not to get any. Some of them can have serious and even life-threatening consequences. In our pregnancy chapter, we remind you how dangerous some of these conditions can be for those who are pregnant. But prevention and timely treatment are both supported by awareness. If you think you have an STI, don’t panic—go to the doctor. And tell any sexual partners so that they can do the same. It is quite common for partners to have an infection too, with no symptoms, and if they’re not tested or treated, they can give the infection right back to you even if you get treatment right away.
People of any sexual orientation can catch STIs, though penis-vagina and penis-anus intercourse may be the most risky activities for transmission of most of these bugs. In the detailed information below, when we say “genital contact,” we also mean penis/anus sex, because virtually all STIs that can be passed during vaginal intercourse are transmissible through anal intercourse as well. In some cases, the mechanics of transmission mean it’s more likely for one gender or the other to get a particular infection, but no sexually active person should be assumed to be immune. And in case you were waiting for scary symptoms to show up before your doctor visit, the most common symptom of an STI is no symptoms at all. So if you’re sexually active, inform your doc so you can get the kind of tests and advice you need. Complete your course of antibiotics or other treatment even if you begin to feel better and your symptoms go away. Some people are quite susceptible to yeast infections when they take antibiotics, and many choose to eat live-culture yogurt or other probiotics to support the “good” bacteria that help keep Candidiasis (yeast) in check.
Here is some basic information about many STIs and conditions—some common, others fairly rare, and a few quite serious. Scientific and medical information is always subject to new insight, so make this the start, and not the end point, of your awareness of STIs.
What is it? While bacterial vaginosis (BV) is not a sexually transmitted infection per se, it is likely that it can be sexually transmitted, and it increases the risk of contracting another STI. That’s why we include it here. BV is caused by an overgrowth of certain bacteria in the vagina that upset the vaginal flora—the natural balance of microorganisms that live in the healthy vagina. It’s an extremely common vaginal infection.
How does one contract it? It’s not always clear how you get BV. It may be more likely if you have a new sex partner or multiple sex partners, which implicates coming into contact with new bacteria and changing the balance in the vagina. Women may be able to pass BV to other women. Douching is also thought to be a risk factor.
What does it do? It increases your likelihood of getting other STIs, including HIV and other infections that may increase the risk of PID (pelvic inflammatory disease).
What are some of its symptoms? You may have no symptoms, or vaginal itching, greyish-white or yellow discharge, and an “off” or fishy smell.
How do you protect from it? Condom use may help.
What are the treatments? Antibiotics, in some cases given in pill form, and in other cases as a vaginal cream.
What is it? A bacterial infection. It is less common in the US and Canada than in other parts of the world; some consider it a “tropical” STI.
How does one contract it? By genital or oral/genital contact with an infected person.
What does it do? It causes genital ulcerations and sores that may be quite painful.
What are some of its symptoms? The sore/s are preceded by a tender raised bump on the external body, or inside the vagina or rectum; painful sex and urination in women; infection can spread to other parts of the body through breaks in the skin; more commonly seen in men; more outbreaks in those who have another STI, and in drug users; and it can affect the lymph glands in the groin and cause them to become swollen and painful.
How do you protect from it? Condoms can help reduce risk.
What are the treatments? Antibiotics.
What is it? Most commonly-reported bacterial STI in the US. One can be re-infected after being cured of a previous case.
How does one contract it? By genital or oral/genital contact with an infected person.
What does it do? It can cause irreversible damage in women, including infertility. It can cause PID; increases chances of transmitting HIV.
What are some of its symptoms? It can cause vaginal discharge and/or bleeding, penile discharge and/or swollen or painful testicles, pain with urination, lower abdominal pain, fever, and—if exposed through anal sex—rectal pain or discharge.
How do you protect from it? Condom use. It can be passed whether or not partner ejaculates. Abstain from unprotected sex until antibiotics have all been taken; any sexually active woman who has multiple partners, a new partner, doesn’t use barriers, or who hasn’t been checked for it recently ought to be tested annually.
What are the treatments? Antibiotics.
What is it? A curable bacterial disease; one can be re-infected.
How does one contract it? By genital or oral/genital contact with an infected person.
What does it do? It can cause heart problems, blindness and arthritis. Can cause PID and other damage to reproductive organs, possible infertility; increases chances of transmitting HIV.
What are some of its symptoms? It can cause thick yellow or grey vaginal discharge, vaginal bleeding, penile discharge and/or swollen or painful testicles, pain with urination and greater urinary frequency, lower abdominal pain, fever, and—if exposed through anal sex—rectal pain or discharge.
How do you protect from it? Condom use. Can be passed whether or not partner ejaculates.
What are the treatments? Antibiotics. Resistant strains are developing, so following doctor’s instructions is very important.
What is it? A bacterial infection. It is rare in the US and Canada; some consider it a “tropical” STI. It is sometimes also called Donovanosis.
How does one contract it? By genital/anal or (much more rarely) oral/genital contact with an infected person.
What does it do? It will continue to spread and affect healthy tissues, leaving lesions called granulomas. It makes other kinds of infections, including STIs, more likely on the affected tissue.
What are some of its symptoms? A painless, beefy-red genital ulcer may lead to more severe lesions; the bacterium, if untreated, will continue to eat away at the tissues.
How do you protect from it? Condom use will help if the infection is on areas of the genitals that the condom protects.
What are the treatments? Antibiotics.
What is it? A viral liver disease.
How does one contract it? By genital or oral/genital contact with an infected person. Also spread via infected blood from needles or other sources of exposure.
What does it do? It may lead to an increased chance of liver disease or cancer.
What are some of its symptoms? Fever, fatigue, loss of appetite; body itching; yellowed eyes and/or skin; dark urine, light-colored stool.
How do you protect from it? The Centers for Disease control suggest that everyone being evaluated/treated for an STI should receive a Hepatitis B vaccine, and men who have sex with men and intravenous drug users should get a Hepatitis A vaccination as well; incubation period is six weeks to six months; all sex partners, injection drug partners, and household members of infected persons should be vaccinated; HIV infection can impair the response to vaccination; because of Hepatitis B’s effect on the liver, alcohol should be avoided in Hep B-positive persons and a doctor should be consulted before taking any new medications, including over-the-counter and herbal remedies. Hepatitis A and C are also considered sexually transmissible in some cases (Hepatitis A especially via rimming and Hepatitis C especially in HIV-positive persons).
What are the treatments? Hepatitis B immunoglobulin and longer-term antiviral therapy are possible treatments. Later-stage hepatitis B can involve, in an extreme case, a liver transplant. There is a vaccine for hepatitis B; at-risk individuals should ask about it.
What is it? Viral disease with no cure that may cause no symptoms or be symptomatic. Most people who have herpes virus likely do not know they are infected; virus can be transmitted from skin that looks normal, not exclusively when lesions/rash are present; some people have “prodromal” symptoms before outbreaks recur.
How does one contract it? By genital or other physical, skin-to-skin contact with an infected person, including oral sex.
What does it do? Systemically affects the body and may be asymptomatic or result in regular or occasional outbreaks.
What are some of its symptom? Blisters or sores at the site of infection are the most noticeable symptom; they may be painful, itchy, and include tingling or shooting pains; can increase the risk of HIV transmission and contracting HIV—it’s being studied whether treating the herpes will have an effect on this transmissibility. Flu-like symptoms can be associated with it, and illness or stress appears to make outbreaks more likely.
How do you protect from it? Depending on the location of the herpes outbreaks, condoms may not protect against transmission if lesions are in a place not covered by the condom. People with recurrent outbreaks may be able to pass the virus at any time if they are not taking suppressive medication, but they must definitely become aware of the “prodrome” stage, before the outbreak is visible but when the lesion site has begun to feel more sensitive, itchy, and tingly—they are shedding virus and contagious at this time.
What are the treatments? Suppressive antiviral medication can be taken daily or at the first sign of a recurring outbreak’s prodrome stage.
What is it? An incurable viral disease that attacks immune system cells, which may give rise to a range of diseases.
How does one contract it? By genital contact with an infected person or via contact with infected blood. Having other STIs increase chances of transmitting and getting HIV, and treating STIs will have some protective effect on this, lessening the risk somewhat.
What does it do? HIV affects CD4 cells (or T-cells) in the immune system, making an infected person unable to fight off disease; AIDS (Acquired Immunodeficiency Syndrome) is diagnosed when various opportunistic infections are present (or when T-cell count falls under two hundred).
What are some of its symptoms? When one contracts HIV they may become ill with flu-like symptoms, including fever, fatigue, and/or swollen lymph glands. Symptoms of HIV’s opportunistic infections include persistent cough, certain body rashes, white spots in the mouth, a yeast infection that won’t go away, and unexplained weight loss and fatigue.
How do you protect from it? Condom use and refraining from coming in contact with inflected blood. PreP (pre-exposure prophylaxis) is a medication that is used to prevent getting HIV; discuss this with your doctor.
What are the treatments? In many cases it can be controlled by antiretroviral medications. Anti-retroviral drug therapy can also lower, though not eliminate, the risk of transmitting HIV during the period of clinical latency, the asymptomatic period before any opportunistic infection manifests.
What is it? A viral disease. It is the most common STI, with around one hundred strains known. It is sometimes called genital (or anal) warts, but many strains of HPV do not result in warts at all.
How does one contract it? By genital or oral/genital contact with an infected person.
What does it do? Some HPV strains cause cancer in some people; warts and cancer both result from changes that the virus has caused in cells—normal cells become abnormal in one way or another; it’s possible to have more than one strain at the same time; most people infected don’t know they have it; it can persist in the body, though some people seem to get over it; those with weak immune systems, including HIV, are probably more likely to have persistent or symptomatic HPV.
What are some of its symptoms? Some strains cause warts: painless growths on or in the anal/genital regions.
How do you protect from it? Condom use.
What are the treatments? The virus can’t be treated, but the problems it causes—from warts to cancer—can be treated appropriately. A vaccine now exists that can prevent the most problematic strains, and young people ages eleven and older are encouraged to be vaccinated. Should susceptible adults be vaccinated? Some docs think it couldn’t hurt.
What is it? These are very small parasites, not microbes. They are sometimes known as “crabs.”
How does one contract it? By genital contact with an infected person; more rarely, from infested linens or clothes. Lice is not just an STI; kids can get lice from each other at school.
What does it do? They live attached to human pubic hairs and feed on blood. They can attach to other hair as well, though when they do they aren’t considered an STI.
What are some of its symptoms? Itching and rash. Can infect other areas with hair, not just the pubic area, including eyelashes and brows; feeling run down or mildly feverish; inflamed skin can occur; the bugs can be seen through a magnifying glass.
How do you protect from it? Avoid sex with a person with lice and contacting infested clothing. Decontaminate bedding, vacuum upholstery.
What are the treatments? Over-the counter or prescription medications can kill the lice and their eggs. Follow instructions carefully.
What is it? A bacterial infection caused by a strain of the Chlamydia bacterium—not the same one that causes the more common Chlamydia infections discussed above. It is less common in the US and Canada than in other parts of the world; some consider it a “tropical” STI. It primarily affects the lymph nodes. More HIV-positive people get it than those without HIV.
How does one contract it? By genital/anal or (more rarely) oral/genital contact with an infected person. It enters through breaks in the skin or via the mucosa.
What does it do? LGV can become a chronic infection of the lymphatic system and cause significant physical changes including swelling and inflammation, rectal scarring, and systemic infection.
What are some of its symptoms? It begins with a painless genital ulcer and progresses to swollen and painful lymph nodes in the groin or, if contracted anally, to rectal symptoms including inflammation, pain, and discharge. Fever and malaise will accompany these symptoms.
How do you protect from it? Condom use.
What are the treatments? Antibiotics; the lymph nodes may need to be drained if abscesses have formed. Partners should be treated too.
What is it? A viral infection. It is less common in the US and Canada than in other parts of the world; some consider it a “tropical” infection. It is often, but not always, sexually transmitted; kids actually are most susceptible, especially in daycare and other group situations.
How does one contract it? By skin, genital, or anal contact with an infected person; by contact with an item that carries the virus, such as a towel or clothing.
What does it do? It results in an outbreak of dome-shaped skin lesions. These may go away on their own, but often it takes a long time. The infection is contagious as long as the lesions are present; once they’re gone, the virus is gone too, and does not go dormant as herpes does.
What are some of its symptoms? The skin lesions are molluscum’s primary symptom. These may itch or become infected and may spread.
How do you protect from it? Condom use, if the lesions are on the penis or an area of the genitals that may contact a penis; handwashing; avoiding infected items and surfaces.
What are the treatments? Molluscum lesions are treated much like warts and may be burned off chemically or via laser or cryotherapy, or scraped off in a process called curettage.
What is it? This is not an STI per se, but rather the outcome of untreated STIs. Progressive infection is most often caused by the gonorrhea and/or chlamydia organisms, but 20% of cases have no certain or identifiable cause.
How does one contract it? It results from untreated or inadequately-treated STIs like gonorrhea, chlamydia, and bacterial vaginosis, which may or may not be sexually transmitted.
What does it do? It infects the uterus, ovaries, and/or fallopian tubes, causing scarring, chronic pain, and sometimes infertility. It is a significant cause of ectopic pregnancy, in which the fetus begins to grow outside the uterus.
What are some of its symptom? Symptoms can include abnormal vaginal discharge and/or bleeding, pain during intercourse and/or urination, abnormal periods (irregular, longer or more painful than usual, constant spotting), fever/chills/nausea/vomiting in serious cases; symptoms can be confused with other, even more serious infections.
How do you protect from it? Avoid bacterial vaginal infections that may lead to it. It’s very important to get treated/checked right away when symptoms begin; women who douche may be at higher risk; male sex partners should be checked for bacterial STIs.
What are the treatments? The underlying pathogen is treated with antibacterial medications and, if pelvic abscesses have formed, with surgery.
What is it? These are very small mites, not microbes.
How does one contract it? By genital or other physical, skin-to-skin contact with an infected person. Like lice, these can be transmitted in other than sexual ways. Very contagious, even through holding hands. Also from infested linens or clothes.
What does it do? Scabies burrow under the skin.
What are some of its symptoms? Intense itching, often worse at night. Red rash, scaly or crusty skin can accompany; a hard-to-see zigzag blister or lesion may be the first thing to appear; usually begins in the body’s folds and crevices.
How do you protect from it? Avoid sex with a person with scabies and contacting infested clothing. Decontaminate bedding, vacuum upholstery; follow treatment instructions carefully.
What are the treatments? Prescription medicines called scabicides will kill the mites.
What is it? A bacterial infection that can damage the body in three distinct stages. Easy to cure in early stages; many US cases are now men who have sex with men, and it disproportionately affects Black and Hispanic communities; puts one at higher risk of contracting HIV; second stage can also include mucous membrane sores; HIV-positive people can get a range of different effects; pregnant women should be tested, and those at risk for, or in high-syphilis areas, should be tested more than once during pregnancy and if positive, treated with penicillin; re-infection can occur.
How does one contract it? By genital or oral/genital contact with an infected person.
What does it do? The infection moves from its point of entry on the body, where it will be marked by a distinctive sore called a chancre, and becomes a systemic disease which can cause severe health problems years later.
What are some of its symptoms? Early-stage symptoms are the chancre, a raised, painless sore/s that will go away on its own, followed by a stage that is marked by a rash and/or mucous membrane sores plus flu-like symptoms; can pass from a pregnant woman to her baby; late-stage syphilis can appear many years later and include organ damage, paralysis, blindness, and dementia.
How do you protect from it? Condom use.
What are the treatments? Antibiotics.
What is it? A genital-tract infection caused by a protozoan. It’s the most common curable STI.
How does one contract it? By genital or oral/genital contact with an infected person.
What does it do? Can cause prostate infection; can increase chances of getting HIV; more common in women, older women more likely to have been infected; having it can make vaginal sex feel unpleasant; can be re-infected, so all sex partners should be treated.
What are some of its symptoms? Vaginal or penile discharge, itching, burning or pain with urination. Often no symptoms: 70% of those infected have no symptoms, and symptom-free people can still pass it to others.
How do you protect from it? Condom use.
What are the treatments? Antibiotics.
What is it? This is not an STI per se, but rather, like PID, may be (but is not always) the outcome of other untreated STIs. It is a bacterial infection that occurs when bacteria invade the urinary tract: the urethra, bladder, kidneys and/or ureters. Women are especially likely to contract a UTI because their urethras are shorter; the bacteria don’t have as far to go to cause trouble. Also known as cystitis or bladder infection.
How does one contract it? In various ways, including via intercourse, which allows bacteria to be pushed into the urethra. These may be the natural bacteria from the anal tract, STI bacteria, or other microorganisms that shouldn’t be in the urinary tract. Holding off on urination is also a risk factor. It may be more common when women are pregnant or in menopause.
What does it do? A UTI results in painful urination and possible kidney infection. The latter is a serious condition.
What are some of its symptoms? A UTI can cause pain or burning with urination and causes urinary urgency—a feeling that you need to urinate right away and can’t hold it—and frequent urination, though you may produce little urine each time. Back pain, chills, nausea, and vomiting may occur if the bacteria reaches the kidneys.
How do you protect from it? Maintain good personal hygiene and wipe from front to back when you use the toilet; at least some UTI doctors say that it’s caused by bacteria in fecal matter 90% of the time and recommend using antiseptic wipes on the vulva after bowel movements. Urinate after intercourse or other insertive sex. Drink lots of water. Using a diaphragm for contraception might increase risk, since this puts extra pressure on the urethra.
What are the treatments? Antibiotics. Some find that acidifying the urine will help—cranberry juice might do the trick, or Vitamin C; it’s also important to drink lots of water to help flush out the bacteria.
What is it? Vaginal inflammation or infection. This is not an STI per se, but rather it may be—but is not always—the outcome of other untreated STIs, including chlamydia, trichomoniasis, and gonorrhea, or can develop from yeast infection or bacterial vaginosis. You can have more than one of these at a time, which may complicate diagnosis and treatment.
How does one contract it? By genital contact with an infected person; other methods depend on which pathogen causes it.
What does it do? Can cause unpleasant vaginal sensations and may be linked to PID and an increased chance of getting other STIs.
What are some of its symptoms? Vaginal discharge, itching, burning with urination, pain or discomfort during sex, especially insertive sex.
How do you protect from it? Condom use will help if a sex partner has an STI, but some vaginitis is not a result of sexual activity or STI infection.
What are the treatments? It depends on the pathogen that has caused the infection. Often, the treatment will involve a course of antibiotics orally or via a vaginal cream.