Chlamydial
Infection
Chlamydial ("kla-mid-ee-uhl")
infection
is the most common bacterial sexually transmitted disease (STD)
in the United States today. The U.S. Centers for Disease Control
and Prevention estimates that more than 4 million new cases
occur each year. The highest rates of chlamydial infection are
in 15- to 19-year-old adolescents regardless of demographics
or location. Pelvic inflammatory disease (PID), a serious complication
of chlamydial infection, has emerged as a major cause of infertility
among women of childbearing age. Chlamydial infection is caused
by a bacterium, Chlamydia trachomatis, and can be transmitted
during vaginal, oral, or anal sexual contact with an infected
partner. A pregnant woman may pass the infection to her newborn
during delivery, with subsequent neonatal eye infection or pneumonia.
The annual cost of chlamydial infection is estimated to exceed
$2 billion.
Symptoms
Most chlamydial
infections are silent, causing no symptoms. However, men and
women with C. trachomatis may experience abnormal genital
discharge or pain during urination. These early symptoms may
be mild. If symptoms occur, they usually appear within one
to three weeks after exposure. Two of every three infected
women and one or two of every four infected men have no symptoms
whatsoever. As a result, often the disease may not be diagnosed
and treated until complications develop.
Doctors
estimate that, in women, one-third of the chlamydial infections
result in PID. Often these infections are not diagnosed until
PID or other complications develop. In men, rarely, chlamydial
infections may lead to pain or swelling in the scrotal area,
which is a sign of epididymitis, an inflammation of a part
of the male reproductive system located near the testicles.
Left untreated, this condition, like PID in women, can cause
infertility.
C.
trachomatis can cause proctitis (inflamed rectum) and
conjunctivitis (inflammation of the lining of the eye). The
bacteria also have been found in the throat as a result of
oral sexual contact with an infected partner. In tropical
climates, a particular strain of C. trachomatis causes
an STD called lymphogranuloma venereum (LGV), which is characterized
by prominent swelling and inflammation of the lymph nodes
in the groin. Complications may follow if LGV is not treated;
this infection is very rare in the United States.
Diagnosis
Chlamydial
infection can be confused with gonorrhea because the symptoms
of both diseases are similar; in some populations they occur
together. The most reliable way to diagnose chlamydial infection
is for a clinician to send a sample of secretions from the
patient’s genital area to a laboratory that will look for
the organism using one of a wide variety of quick and inexpensive
laboratory tests. Although attempting to grow the organism
in specialized tissue culture in the laboratory is one of
the most definitive tests, it is expensive and technically
difficult to do, and test results are not available for three
or more days.
Scientists
have developed several rapid tests for diagnosing chlamydial
infection that use sophisticated techniques and a dye to detect
bacterial proteins. Although these tests are slightly less
accurate, they are less expensive, more rapid, and can be
performed during a routine checkup. These tests use a process
called DNA amplification to detect the genes of the organisms
in genital secretions. Recently, the U.S. Food and Drug Administration
approved this process for detection of C. trachomatis in
urine. This is a major step in diagnosing chlamydial infection
because it does not require an invasive sample; it can be
used in settings where performing a pelvic examination is
not convenient or not feasible, e.g., in college health units
and at health fairs. Results from the urine test are available
within 24 hours.
Treatment
Doctors
usually prescribe antibiotics such as a one-day course of
azithromycin or a seven-day course of doxycycline to treat
chlamydial infection. Other antibiotics such as erythromycin
or ofloxacin also are effective. Pregnant women can be treated
with azithromycin or erythromycin. Amoxicillin is also a safe
alternative for treating pregnant women. Penicillin, which
is often used for treating some other STDs, is not effective
against chlamydial infections. New medications are being developed
that should greatly simplify treatment and help control the
spread of C. trachomatis in the population.
A person
with chlamydial infection should be sure to take all of the
prescribed medication, even after symptoms disappear. If the
symptoms do not disappear within one to two weeks after finishing
the medicine, the patient should make a follow-up visit to
the doctor or clinic. All sex partners of a person with chlamydial
infection should be tested and treated to prevent reinfection
and further spread of the disease.
Pelvic
Inflammatory Disease
Each year
up to 1 million women in the United States develop PID, a
serious infection of the reproductive organs. As many as half
of all cases of PID may be due to chlamydial infection, and
many of these occur without symptoms. PID can result in scarring
of the fallopian tubes, which can block the tubes and prevent
fertilization from taking place. An estimated 100,000 women
each year become infertile as a result of PID.
In other
cases, scarring may interfere with the passage of the fertilized
egg down into the uterus. When this happens, the egg may implant
in the fallopian tube. This is called ectopic or tubal pregnancy.
This is life-threatening for the mother and results in the
loss of the fetus. PID is the most common cause of pregnancy-related
death among poor teenagers in the inner cites and rural areas
of the United States. The annual cost estimates exceed $7
billion.
Effects
of Chlamydial Infection in Newborns
A baby
who is exposed to C. trachomatis in the birth canal
during delivery may develop conjunctivitis (eye infection)
or pneumonia. Symptoms of conjunctivitis, which include discharge
and swollen eyelids, usually develop within the first 10 days
of life. Symptoms of pneumonia, including a progressively
worsening cough and congestion, most often develop within
three to six weeks of birth. Both conditions can be treated
successfully with antibiotics. Because of these risks to the
newborn, many doctors recommend routine testing of all pregnant
women for chlamydial infection.
Prevention
Because
chlamydial infection often occurs without symptoms, people
who are infected may unknowingly infect their sex partners.
Many doctors recommend that all persons who have more than
one sex partner, especially women under 25 years of age, be
tested for chlamydial infection regularly, even in the absence
of symptoms. Using condoms or diaphragms during sexual intercourse
may help reduce the transmission of chlamydia.
Research
NIAID
researchers are working on two strategies to prevent infection:
topical microbicides and a vaccine. Scientists also are looking
for better ways to treat people with chlamydial infection.
In addition, developing simple, inexpensive tests to diagnose
chlamydial infection remains one of the most urgent research
priorities.
Scientists
also are studying the basic process of how C. trachomatis
causes disease in the body and why some people suffer
more severe complications than others. These studies may lead
to insights about how to recognize women at risk for PID and
PID-related infertility or other complications of chlamydial
infection.
For More Information
American Social
Health Association
P.O. Box 13827
Research Triangle Park, NC 27709-9940
800/230-6039
National Institutes
of Health
June 1998
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