Chlamydia is one of the most common sexually transmitted diseases (STDs) worldwide and in the United States. It can infect both men and women, though it is more common in young women.

This comprehensive post discusses

  • What causes chlamydia in men and women?
  • What are the symptoms and complications in both sexes?
  • How it is diagnosed?
  • How chlamydia and its complications are treated?

Chlamydia is a sexually transmitted infection (STI) or disease (STD). You mostly get it through any sexual act with a person who is already infected with this disease.

According to the Centers for Disease Control and Prevention (CDC), women with chlamydia infection increase their risk of catching HIV five times if exposed to a partner with HIV. Condoms if used correctly offer good protection against it.

Why is chlamydia so common and dangerous?

What makes chlamydia dangerous is the fact that it exhibits no symptoms in a significant number of cases and therefore, is unknowingly passed to a healthy person.

75% of the women and 50% of the men infected with uncomplicated chlamydia do not have any symptoms. They, therefore, do not know they have this disease and unknowingly keep on passing it to their sexual partners. This is what makes chlamydia so widespread. It is the most common sexually transmitted disease worldwide.

About one million individuals are infected with this STD in the United States. However, chlamydia is easily treated and cured.

If left undiagnosed and untreated, it can damage the reproductive system in women, which can lead to infertility (inability to get pregnant) or to ectopic pregnancies (pregnancy outside the uterus).

What causes chlamydia?

Chlamydia is caused by the bacteria Chlamydia trachomatis. This is one of the four strains of the Chlamydia bacillus and has evolved over the years to form new strains with the exchange of DNA between the four strains of the genus Chlamydia. It also causes infection of the eyes and is the most common cause of blindness worldwide.

What doesn’t cause chlamydia?

Not all interacting situations that involve an exchange of body fluids or close contact intimacy cause chlamydia. You cannot  get chlamydia from:

  • Kissing
  • Sharing food or drinks
  • Hugging
  • Holding hands
  • Using a common toilet after an infected person has used it
  • Inhaling droplets released by an infected person from coughing or sneezing

Transmission and risk factors

Chlamydia is transmitted or spread by sexual acts with an infected person. This act may be vaginal, oral, or anal. It is also transmitted from an infected mother to her newborn during normal vaginal delivery.

You are less likely to get chlamydia from oral sex because the bacteria that cause chlamydia have an affinity to target the genital area rather than the throat.

You are at an increased risk of catching chlamydia if you fall into any of the following groups.

  • The age group is below 24 years. This is the most consistent risk factor with the highest prevalence in women between ages 16-19 years and in men between 20-24 years
  • Active sex life with multiple partners,
  • You have unprotected sex meaning not using condoms during sex,
  • Men having sex with men (MSM)
  • History or presence of another existing  sexually transmitted disease
  • Economically weaker status

Why young women are more susceptible to chlamydia infection?

Possible causes for young women being more susceptible include:

  • Possible partial immunity to this infection in older women
  • Younger women tend to be riskier in their sexual behavior such as indulging in anal intercourse
  • Biological factors, such as cervical ectopy, are physiological conditions seen in many younger women. This is a condition where the lining of the inside of the cervical canal extends outwards onto the surface of the cervix thereby increasing the chances of catching the chlamydia infection.

What is the risk of chlamydia infection from one unprotected sexual encounter?

Among the bacterial STDs, chlamydia is the most easily transmissible disease. The possible rate of transmission from one sexual encounter per sex act with a chlamydia-positive individual is approximately 4.5 %. However, this rate is slightly higher for receptive sex.

The quantum of risk varies in men and women.
  • In men, the risk of getting chlamydia from one sexual encounter is 20%
  • In women, the risk is 40%

Chlamydia symptoms

Chlamydia is the most common bacterial sexually transmitted infection (STD). This is one STD, that can fool you into believing that you are not infected when in fact you are.

This is because in most cases, this STD exhibits no symptoms. 75% of the women and 50% of the men infected with uncomplicated chlamydia do not have any symptoms. This is why this chlamydia is referred to as “the silent infection”.

This is what makes it spread very fast and transmitted innocently because though the person is infected, he does not know it, does not take treatment to cure it, and goes on passing the infection to others.

When symptoms do occur, they do so within one to three weeks after exposure and getting infected. This is called the incubation period of chlamydia.

Symptoms in men

Chlamydia symptoms in men are mostly due to urethritis (infection of the urethra). They include:

  • Discharge from the penis can be clear or cloudy. It is less cloudy and less in quantity when compared to the gonorrhea discharge.
  • Burning urination
  • Burning and itching around the urethral opening on the penis
  • Swelling and pain around the testicles
  • Low-grade fever
  • Swelling around the anus due to receptive anal sex

In some men, the symptoms can be mild so as to go unnoticed. The symptoms may even disappear after two or three days.

If this is ignored and left untreated, this can lead to complications such as orchitis (infection of testicles) and sterility. These mild symptoms in men usually appear in the morning. Men should therefore be on the lookout for such symptoms that can be missed.

Symptoms in women due to vaginal infection include

  • Low-grade fever
  • Abnormal vaginal discharge
  • Yellowish discharge from the cervix that has a strong odor
  • Burning urination
  • Painful menstruation with more bleeding
  • Irregular bleeding in between periods
  • Sex is painful and causes bleeding
  • Burning around the vagina
  • Increased frequency of urine
  • Lower abdominal pain

If left untreated in women, chlamydia causes complications such as pelvic inflammatory disease (PID) in 40% of the cases. PID is an infection of the pelvic organs such as the ovaries, fallopian tubes, and uterus.

Symptoms of rectal infection due to anal sex

  • Rectal pain
  • Anal discharge
  • Swelling around the anus
  • Bleeding from the anus

Symptoms of throat infection of the throat due to oral sex

  • Soreness of throat
  • Pain while swallowing
  • Cough
  • Fever

Chlamydia Statistics Worldwide And U.S.

Worldwide stats:

  • Stats of 2010 show that it affects 215 million people globally – a little more than 3% of the population. 1200 people died of Chlamydia in that year against 1500 deaths in 1990.
  • The prevalence is highest in the sexually active population under 24 years of age
  • It is more common in women (3.8%) than in men (2.5%)

Death statistics worldwide

  • About 1,000 deaths from chlamydia in Africa in 2002 (The World Health Report, WHO, 2004)
  • About 8,000 deaths from Chlamydia in South East Asia in 2002 (The World Health Report, WHO, 2004)
  • About 1,000 deaths from Chlamydia in Eastern Mediterranean in 2002 (The World Health Report, WHO, 2004)

United States stats

  • Incidence: There are approximately 2.8 million new cases of chlamydia every year.
  • Epididymitis is seen in about 250,000 men in the US every year and occurs as a complication of chlamydia.
  • Similarly, pelvic inflammatory disease, another complication is seen in about 250,000 to 500,000 women every year.
  • Approximately one in ten adolescent girls is infected with chlamydia (The National Women’s Health Information Center, CDC)
  • Estimated 1 in 20 women of reproductive age in the US (The National Women’s Health Information Center, CDC) infected with chlamydia
  • 50% likelihood of infection by the time women reach the age of 30 years (The National Women’s Health Information Center, CDC)
  • Prevalence: 2 million people currently infected in America (Tracking The Hidden Epidemics, CDC, 2002)

Stats for U.K.

In the UK, Chlamydia is the most common sexually transmitted infection with 161,672 diagnoses in 2020.

Chlamydia complications in men, women, and newborn

The effects of chlamydia complications can be dangerous in men and women, more so in women, if this sexually transmitted disease is left untreated. The consequences can be short-term and long-term.

Chlamydia can be cured completely with the right treatment. Once cured, you can catch this sexually transmitted disease again if you get reinfected. You then have to take treatment again.

Chlamydia is very common and dangerous – dangerous because 75% of women and 50% of men do not get any symptoms. They are infected but do not know it.

They unwillingly pass on the infection to others.  They do not get treated and as a result, this can cause complications, some of which can be treated while others are irreversible.

Complications common in both men and women

  • Acquiring other sexually transmitted infections. Having chlamydia increases your risk of acquiring other sexually transmitted diseases like HIV (AIDS virus) and gonorrhea.
  • Reactive arthritis. Reactive arthritis, another complication of untreated chlamydia, can affect both men and women though it is seen more in men. It causes inflammation of the joints. Formerly it used to be referred to as Reiter’s syndrome and can comprise a triad of symptoms in some individuals. Besides joint pain, these individuals also develop urethritis (inflammation of the urethra) and conjunctivitis (inflammation of the eyes). These symptoms of Reiter’s syndrome can resolve in two to three months’ time but can recur. Usually, non-steroidal anti-inflammatory painkillers like Ibuprofen give relief, but severe cases of joint pain will need more active orthopedic treatment.

Complications in women

  • Pelvic inflammatory disease (PID). Pelvic inflammatory disease (PID) is a serious infection of the pelvic reproductive organs of a woman. These organs are the ovaries, the fallopian tubes (salpingitis), the uterus (endometritis), and the cervix (cervicitis). PID occurs as a complication of untreated chlamydia infection due to its bacteria invading these organs by traveling up the vagina into the reproductive tract. About 2% to 5% of women who have chlamydia develop PID. The onset of PID in infected and untreated women can be sudden, resulting in high fever and pelvic pain or the PID can develop slowly over a period of months or even years. Such slowly developing PIDs can be without any symptoms. They are called silent PIDs. In both cases, damage occurs to the reproductive organs. PID can cause severe damage to these organs, which can result in complications such as miscarriages, ectopic pregnancies, and even infertility. PID can at times be asymptomatic and when symptoms are present, they include fever and chronic lower abdominal pain. If treated early, treatment with antibiotics can give relief, and the risk of these complications is reduced. Severe cases may require hospitalization to administer intravenous antibiotics.
  • Swelling of Bartholin’s glands (Bartholinitis). These are the glands situated on both sides of the vaginal opening. They produce lubricating mucus to facilitate sexual intercourse. Chlamydia infection causes these glands to become infected leading to their blockage. These glands then become swollen and form a cyst, which if infected can result in an abscess. This requires treatment with antibiotics or even surgical drainage (a minor surgical procedure).

Complications in men

  • Urethritis. Urethritis is an infection of the urethral canal. This is the small canal that runs on the underside of the penis to facilitate the passing of urine from the bladder to the outside. Urethritis has other causes too but chlamydia is the most common.
  • Epididymitis. The epididymis is a tightly coiled thread-like tube present in each testicle. It carries the sperm from the testes to the vas deferens and forms an important part of the male reproductive system. Untreated, chlamydia can cause infection of the epididymis. This can give rise to fever, pain, swelling, and tenderness over the scrotum. If left unattended, this can develop into an abscess. At times, the testicles may also get infected. This is called epididymo-orchitis.
  • Prostatitis. The prostate, another important organ of the male reproductive system, makes the fluid part of the semen. It is situated beneath the urinary bladder. Chlamydia can cause prostatitis (infection0, which can result in:
    • swelling of the prostate,
    • burning pain while passing urine,
    • painful sex
    • increased frequency of urine
    • fever with chills may or may not be present.
  • Sterility is another effect of chlamydia complication that can arise as a result of long-standing epididymitis and/or prostatitis. However, if treated early, this complication is reversible.

Complications in pregnancy and newborn

Chlamydia complications in pregnancy include preterm labor, miscarriage, ectopic pregnancy, and chronic pelvic pain due to damage to the pelvic organs. The pelvis organs get scarred and fibrosed due to chronic infection.

In a pregnant woman who has chlamydia that has not been treated, the newborn delivered naturally through the vaginal canal gets exposed to the infection and it can develop complications such as eye infection (conjunctivitis), ear infection (otitis media), infection of the nose and throat and lung infection (pneumonia).

If these complications are not promptly treated, they can become serious. After delivery, the uterus of the woman gets infected causing late postpartum endometritis (infection of the inner lining of the uterus).

Chlamydia diagnosis

Testing to diagnose chlamydia trachomatis assumes great significance due to the fact that the majority of people who suffer from it do not develop symptoms. Testing for chlamydia infection then is the only way to find out if you are infected.

50% of men and 75% of women who get infected do not have any symptoms. After a doubtful sexual encounter, one must therefore be tested even if you do not have any symptoms.

There is no reliable blood test to detect chlamydia infection. Chlamydia tests are carried out on samples of body fluid or urine.

The body fluid sample in women is obtained with a swab from the endocervix (cervical canal) or the vagina, oral fluid from the oral cavity in case of oral sex, and a swab from the anal canal in case of anal sex.

In men, the body fluid sample is obtained from inside the urethral opening and similarly from the oral cavity and the anal canal.

The laboratory tests to diagnose chlamydia include:

1. Nucleic acid amplification tests (NAAT)

NAATs are fairly accurate tests performed on the fluid sample and are based on the amplification of the DNA that is found in Chlamydia trachomatis. These tests include polymerase chain reactions (PCRs) and transcription-mediated amplification (TMA). These are molecular tests that detect and make copies of the DNA of the chlamydia bacteria. They can also be performed on a urine sample.

2. Nucleic acid hybridization test

This is also called the DNA probe test, or molecular probe test. This is molecular probe testing which detects the DNA of the Chlamydia trachomatis. This test can differentiate the gonococci from the chlamydia bacteria and is faster than the culture test. This test is quite accurate but not as sensitive as NAAT.

3. Enzyme-linked immunosorbent assay (ELISA, EIA)

This test is performed on the fluid or material obtained from the patient. It detects the antibodies that are produced by the immune system to fight the chlamydia infection. This test is not as accurate as the culture test or the molecular probe test.

4. Chlamydia culture and sensitivity

A culture is done of the fluid material collected. Proper testing techniques are necessary for accuracy. This test is advised if you have taken treatment and the symptoms persist. This test can also tell to which antibiotics the chlamydia bacteria are resistant. Treatment can then be changed to an antibiotic to which the bacteria are sensitive.

Currently, the standard for diagnosis of chlamydia trachomatis infection is culture, though according to research, in adults, NAAT studies are superior.

In cases of children subjected to abuse, researchers advise that urine NAATs offer a clear advantage over culture in terms of sensitivity and reduce the trauma and discomfort of swab removal in the patient.

How the swab is taken of the fluid sample for chlamydia testing?

  • From the penis in men: First, the penis is gently squeezed from its base to its end to move the secretions forward. A thin swab is then inserted approximately one centimeter and kept in place for about 30 seconds to allow it to absorb the secretions. It is then removed and sent for testing.
  • From the endocervix in women: The outer part of the cervix (ectocervix)  is first cleaned with a large swab. A thin swab is then inserted into the cervix for about 30 seconds allowing it to absorb the secretions. It is then sent for testing.
  • From the mouth: The patient is first asked to swallow or spit off any saliva that may be in the mouth. Oral fluid (not saliva) is then taken by gently but firmly moving the swab over the gums.

Chlamydia window period: When should you test for Chlamydia?

This is the period that corresponds to the time taken for the tests to show positive results after the person has gotten infected. In the case of chlamydia, you should wait for two weeks after the doubtful sexual encounter to test for the infection. In other words, the window period for chlamydia is two weeks.

At what periods is screening for chlamydia advised?

  • Screening should be done once a year in sexually active women under the age of 24 years and older women who have a high-risk sexual lifestyle.
  • During the first and last trimesters in all pregnant women
  • Women who have any pelvic infection (PID)
  • All men and women who frequently change partners should be screened frequently, either on a quarterly or half-yearly basis.
  • Men who have sex with men (MSM) should also be tested frequently.

Antibiotic treatment to cure chlamydia trachomatis infection

Once diagnosed, the chlamydia infection is easily treated and cured with antibiotics and they form the mainstay of its treatment. Co-infection with HIV does not change the therapy to cure chlamydia.

Chlamydia treatment with antibiotics can be given as a single dose or a seven-day course. The antibiotics differ. The person who is infected should not indulge in any form of sexual activity for seven days after having taken the single-dose therapy or completed the seven-day course. He or she can still pass on the infection during this period.

Once you have found that you are infected, you are morally bound to inform your partner/s to test for the chlamydia infection and be treated if necessary.

Once cured of the chlamydia infection, you can still get the infection again if you have sex with a partner who is infected. In other words, once cured does not mean you are immune to further chlamydia infection.

The Centers for Disease Control (CDC) recommends the following treatment options for treating chlamydia trachomatis:

The most commonly used antibiotics are:

  • Azithromycin 1 gm orally in a single dose
  • Doxycycline 100 mg orally twice a day for 7 days

Alternative Regimens for Non-Pregnant Adults

  • Erythromycin base 500 mg orally four times a day for 7 days
  • Erythromycin ethylsuccinate800 mg orally four times a day for 7 days
  • Ofloxacin 300 mg orally twice a day for 7 days
  • Levofloxacin 500 mg orally once daily for 7 days

Treatment of chlamydia in pregnancy

In pregnant women, Doxycycline, Ofloxacin, and Levofloxacin are not recommended because of their toxic effects on the fetus.  Azithromycin or erythromycin then become the antibiotics of choice to treat chlamydia in pregnant women.

After having successfully taken the treatment, men and women should be tested again after three months after having completed the treatment for the initial infection to confirm a complete cure.

Treatment of women with pelvic inflammatory disease (PID)

PID is a common complication of untreated chlamydia in women. PID requires hospitalization for the use of intravenous antibiotics. In very severe cases of PID, surgical intervention along with antibiotics may be necessary to repair the organ involved or even for its removal.

Treatment of infants

Infants who have acquired the chlamydia infection at birth from their mothers are treated with antibiotics. They have the risk of getting conjunctivitis and/or pneumonia. To avoid this, maintain eye hygiene as advised by your doctor and prevent the infant from touching its eyes with its hands. Azithromycin is given orally and antibiotic eye ointments are used.