Chlamydia

Definition:

A sexually-transmitted disease caused by microorganisms that live as parasites within a cell. These microorganisms have properties in common with both viruses and bacteria, and cause infection in humans.

Causes, incidence, and risk factors:

Chlamydia infection is caused by the organism Chlamydia trachomatis. It is thought to be the most common sexually-transmitted disease in the United States with an estimated 3,000,000 to 4,000,000 cases per year. (In comparison; 2,000,000 cases of gonorrhea, reported and unreported, are thought to occur in the United States annually). The incidence is higher among lower socioeconomic groups and among teenagers.

Chlamydia is significantly important because of the consequences of untreated infection. The majority of genital chlamydia infections are without symptoms (asymptomatic) until complications appear.

Chlamydia (male):
In men, chlamydia produces symptoms similar to gonorrhea, and can also cause epididymitis and orchitis.

Chlamydia (female):
Infection with chlamydia frequently leads to pelvic inflammatory disease (PID) which can cause scarring of the Fallopian tubes and sterility. An estimated 20% of women who develop PID will become infertile. Tubal scarring also increases the likelihood of an ectopic pregnancy (tubal pregnancy). If a women is infected with chlamydia while pregnant the infection can cause premature labor and delivery. In addition the infant has a greater than 1 in 3 chance of developing chlamydial conjunctivitis (eye infection) and a 15% chance of developing chlamydial pneumonia (30,000 cases are reported in the U.S. each year).

A majority of chlamydial infections do not cause symptoms; but when symptoms are present, they are similar to those of gonorrhea. In men, this may include burning with urination, discharge from the end of the penis (urethral discharge), tenderness or pain in the testicles and lower abdomen and fever and chills (when epididymitis develops). Women may also have urinary burning, increased frequency, and a mild urethral discharge. Infection of the female reproductive tract can include the Bartholin ducts, vagina, cervix, endometrium, and fallopian tubes (salpingitis and PID).

Chlamydia can also cause rectal infections and is a cause of proctitis in both males and females.

There are three strains of chlamydia that are responsible for another sexually-transmitted disease, called lymphogranuloma venereum. This disease is seen more commonly in underdeveloped countries but has world-wide distribution. In the United States it is seen more commonly in homosexual men and is a cause of proctitis and colitis (inflammation of the lower intestine).

Chlamydia infection is often found in conjunction with gonorrhea. People who are diagnosed with gonorrhea should also be evaluated for chlamydia infection.