Facts, Symptoms, and Stages of Sexually Transmitted Infections

Information About Syphilis, Gonorrhea, Chlamydia & Trichomoniasis

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Sexually transmitted infections (STIs, also referred to as sexually transmitted diseases, or STDs) are among the most common causes of illness in the world. In some populations, one STI, syphilis, is at epidemic proportions.

Also, having a sexually transmitted infection, including syphilis, increases your risk of acquiring human immunodeficiency virus (HIV). In the case of syphilis, the open sores caused by this sexually transmitted infection are an ideal portal for HIV to enter the body.

This article will give an overview of four sexually transmitted infections, including their causes, symptoms, and treatments.

Vial and STD form
Rodolfo Parulan Jr. / Getty Images


Syphilis was first identified in the 16th century. In industrialized countries, syphilis declined during the latter half of the nineteenth century. However, in these same countries, there was a sharp rise in incidence of this STI after World War I.

But once again, following World War II the incidence fell rapidly, coinciding with the availability of improved diagnostic tests and antibiotics. In some industrialized countries syphilis began to rise again in the 1960s and has been increasing steadily since.

Controlling Syphilis

Syphilis is the classic example of an STI that can be successfully controlled by public health measures, including:

  • A simple, highly sensitive diagnostic test is available and allows for early diagnosis.
  • Highly effective antibiotics are available to treat an acute and chronic infection.
  • If syphilis is left untreated, it can cause nerve damage, arterial wall damage, mental disorientation, and eventually death.
  • Resistance to the antibiotics has not developed, meaning they will be effective for most people.

How Do People Contract Syphilis?

Syphilis is caused by a bacterium, specifically, a motile (able to move) spirochete (corkscrew-shaped bacterium) known as Treponema pallidum. The spirochete is passed from person to person through oral, anal, and vaginal sex.

Syphilis causes open sores, primarily on the penis, anus, and vagina. Contact with those sores during oral, vaginal, or anal sex allows for the transfer of the spirochete sexually from one person to another.

In addition to being sexually transmitted, syphilis can be passed from a pregnant person to the unborn baby. The spirochete that causes syphilis can cross the barrier between fetus and mother (the placenta), infecting the fetus.

Syphilis infection of an unborn fetus can result in spontaneous abortion, stillbirth, or death of the fetus while in the mother's womb. For those babies who make it to delivery and survive, birth defects are common.

What Are the Symptoms of Syphilis?

Syphilis has been called an "imitator," and its symptoms are often confused with the symptoms of other conditions and diseases. People with syphilis can go years without symptoms at all. In fact, in the early stages of the disease, if there are syphilis sores, they may go unnoticed. These two characteristics of syphilis mean most infections occur between people who are unaware of their syphilis infection.

The 3 Stages of Syphilis Infection

Primary stage: Typically, during this stage, a single sore erupts on the genitals, vagina, or anus. Usually, this occurs about 10–90 days after infection. The round painless sore typically appears at the point where syphilis entered the body. This sore will last for three to six weeks and heals without treatment. However, treatment is suggested because, without it, syphilis can enter the secondary stage.

Secondary stage: With or without treatment, the symptoms of secondary syphilis will heal. But as is the case in the primary stage, without treatment the infection can progress to the late stage. The secondary stage of syphilis is characterized by:

  • Mucous membrane lesions
  • A red to reddish-brown rash on the palms of the hands and soles of the feet that does not itch
  • Fever
  • Swollen lymph nodes
  • Sore throat
  • Hair loss
  • Weight loss
  • Muscle aches
  • Fatigue

Late stage: This stage is also known as the "hidden stage," starting when the symptoms of the secondary stage have resolved. It's this stage in which untreated syphilis can cause damage to internal organs, the central nervous system, and to bones and joints. In some cases, death can occur. For this reason, treatment of syphilis is important regardless of what stage of the infection a person is in.

How Is Syphilis Treated?

In its early stages, syphilis is easily treated with a single injection of penicillin or a similar antibiotic if a penicillin allergy exists. As the stages of penicillin progress, the treatments are for a longer period of time and are more invasive (e.g., intravenous vs. intramuscular injection).

Having syphilis once and being successfully treated does not protect the person from future infections. For this reason, safer sex precautions need to continue, and regular testing is a must.


Another of the four most common STIs is gonorrhea. But like the others, a little bit of protection can prevent gonorrhea altogether. And like other STIs, the presence of any STI including gonorrhea can increase the risk of HIV infection.

Gonorrhea is a common adult disease, though a significant proportion of those with infection (up to 80% of women and 10% of men) are asymptomatic, meaning they do not have symptoms. Therefore, they are neither aware of the need for treatment nor of the risk of transmitting the disease to others. It's this lack of awareness that contributes to the number of gonorrhea cases each year.

How Does Gonorrhea Infection Occur?

Gonorrhea is an STI caused by the bacterium Neisseria gonorrhoeae. This bacterium loves to grow in warm, moist areas, including the vagina, anus, urinary tract, mouth, throat, and eyes. Therefore, any unprotected sexual contact with these areas has the potential to cause infection.

Infection can occur during unprotected anal, vaginal, or oral sex. Ejaculation of semen is not required for infection to occur. Also, gonorrhea can be spread from an infected mother to her baby during delivery.

What Are the Symptoms of Gonorrhea?

Many men have no symptoms at all. If they do have symptoms, they usually appear within a week of infection and include:

  • Burning with urination
  • A white, green, or yellow discharge from the penis
  • Painful or swollen testicles

Women frequently have only minor symptoms or have no symptoms at all. Because of this, detection of infection depends mainly on vaginal culture. If women have symptoms, they include:

  • Pain or burning with urination
  • Vaginal discharge
  • Vaginal bleeding between periods

Both men and women can get a rectal gonorrhea infection. Symptoms include:

  • Rectal discharge
  • Anal itching or pain
  • Anal bleeding
  • Painful bowel movements

A gonorrhea infection in the throat rarely causes symptoms but if it does, it's usually a sore throat.

How Is Gonorrhea Treated?

There are several antibiotics that are successful in treating gonorrhea. However, gonorrhea strains that are resistant to antibiotics are becoming more common and make it much more difficult to treat the STI. Often, a person with gonorrhea can be infected with another STI known as chlamydia. If the person has both infections, both need to be treated. The  person will take antibiotics to treat both.

If gonorrhea is not treated completely, it can cause other serious and permanent illnesses. These other illnesses include:

  • Infection of the uterus, ovaries, or fallopian tubes (pelvic inflammatory disease) in women
  • Increase the risk of ectopic pregnancies
  • Testicular infections (epididymitis)
  • Blood and joint infections

Preventing Gonorrhea

As with any STI, using latex condoms can decrease the risk of getting infected with gonorrhea. While a person is being treated for gonorrhea, they must avoid sexual contact.

When a person is diagnosed with gonorrhea, they must inform their sexual partners, who should also be tested and treated for gonorrhea.


Chlamydia is the most frequently reported STI in the world, even though the infection is substantially underreported. Because the symptoms of chlamydia are mild or absent, people who have chlamydia often are unaware of the infection.

Chlamydia, like gonorrhea, is a common adult disease that has asymptomatic (without symptoms) rates in women similar to those for gonorrhea, but higher rates of asymptomatic infection than gonorrhea in men. It is caused by the bacterium called Chlamydia trachomatis.

As with gonorrhea, chlamydia can cause such things as pelvic inflammatory disease and infertility. Diagnosis of chlamydia is widely available in the western world. However, the test for chlamydia is costly and not generally available in developing countries. This means that around the world, many chlamydia infections go undetected and untreated.

How Does Chlamydia Infection Occur?

As the term "sexually transmitted infection" suggests, chlamydia is spread from person-to-person during unprotected anal, vaginal, or oral sex. In addition, chlamydia can be passed from the mother to her newborn baby during vaginal childbirth. While any sexually active person is at risk for infection, some people have a higher risk than others, including:

  • Teenage girls have a higher risk because their cervix is not fully matured, and the protective characteristics of a mature cervix are absent.
  • Because chlamydia can be spread during oral and anal sex as well as vaginal sex, men who have sex with men have an increased risk of infection.

What Are the Symptoms of Chlamydia?

About 75% of women and 50% of men who have chlamydia have no symptoms. But in the rest, symptoms do appear about one to three weeks after infection.

In women, these symptoms include:

  • Vaginal discharge
  • Burning or pain during urination
  • Abdominal and/or low back pain
  • Nausea
  • Fever
  • Pain with intercourse
  • Vaginal bleeding between periods

Symptoms in men include:

  • Burning or pain during urination
  • Penile discharge
  • Burning and itching around the opening at the tip of the penis

If left untreated, chlamydia can cause permanent damage to the reproductive system. However, the damage that the untreated chlamydia causes may go unnoticed because often there are no symptoms. For this reason, treatment of chlamydia is recommended with or without symptoms.

How Is Chlamydia Treated?

Fortunately, treatment of chlamydia is easy and effective. Treatment can consist of a single dose of an antibiotic or a week's worth of antibiotics twice daily. During treatment, sexual activity should not occur. Partners of the person with chlamydia should be tested for chlamydia and treated if infected.

Women and teenage girls should be retested a few months after treatment. Because of the risk of reinfection from an untreated partner and the potential harm chlamydia can do to the reproductive system it is important to make sure the chlamydia has been treated completely and that reinfection has not occurred.


The common sexually transmitted infection trichomoniasis affects both men and women, but symptoms are more common in women. The disease is caused by a one-cell parasite called Trichomonas vaginalis.

Trichomoniasis causes symptoms in approximately 50% of infected women. In men, infection is usually urethral (urinary tract) and lasts only a short time. However, men easily transmit the parasite to women during the short period when they are infected.

How Does Trichomoniasis Infection Occur?

Trichomoniasis is spread from person to person by way of unprotected sexual contact. The vagina is the most common site of infection in women and the urethra (urinary tract) is the most common in men. Women can get infected by men or women by direct sexual contact. Men are most commonly infected by women.

What Are the Symptoms of Trichomoniasis?

If symptoms do occur, they usually appear within four weeks of exposure. Symptoms in women include:

  • Genital inflammation
  • Foul-smelling, yellow-green vaginal discharge
  • Pain with intercourse and/or urination
  • Vaginal irritation and itching
  • Abdominal pain (uncommon but occurs at times)
  • Premature or low-birth-weight babies (a baby weighing less than 5 pounds)

Most men have few or no symptoms at all. If they do have symptoms, they are usually mild and don't last very long. They include:

  • A sensation of irritation "inside" of the penis
  • Penile discharge
  • Burning after urination and/or ejaculation ("cumming")

Genital inflammation can increase the risk of HIV infection in women. Also, trichomoniasis infection in HIV-positive women increases the risk of passing HIV to male sexual partners.

How Is Trichomoniasis Treated?

Women are easily treated with a single dose of an antibiotic called Flagyl (metronidazole). In men, their infection will usually go away without treatment. However, because men are often unaware of their infection, they can reinfect their female partners over and over again.

Therefore, treatment of both partners is recommended when one partner has been diagnosed. This way, the parasite can be cured in both partners and the cycle of reinfection can be stopped.

How Can Trichomoniasis Be Prevented?

Ways to prevent yourself from getting the infection and passing it on include:

  • People should use latex condoms with each and every sexual contact.
  • Sexual activity should stop, a diagnosis should be made, and treatment of the person and all sexual partners should be given if any symptoms of infection exist.
  • Sexual activity should stop until treatment is completed and all symptoms have resolved.
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By Mark Cichocki, RN
Mark Cichocki, RN, is an HIV/AIDS nurse educator at the University of Michigan Health System for more than 20 years.