Author: Dr H. Hunter Handsfield Clinical Professor of Medicine University of Washington
2008-10-28
2008-10-28
CHLAMYDIA : The Most Common Bacterial STD
Chlamydia trachomatis inclusion bodies. Source: Public Health Image Library (CDC) |
Genital infection with chlamydia—scientific name Chlamydia trachomatis—is the most common bacterial sexually transmitted disease (STD) in industrialized countries and probably worldwide. Three to 4 million cases are estimated to occur in the United States each year and the World Health Organization estimates at least 90 million annual cases worldwide. The primary anatomic sites of infection are the urethra in men and the uterine cervix and urethra in women. Infections of the rectum, acquired through receptive anal intercourse, also are common, especially among men who have sex with men (MSM). As for most STDs, chlamydia presents the greatest health threat in women, primarily through infection that ascends from the cervix to involve the uterus and Fallopian tubes, resulting in pelvic inflammatory disease (PID). Chlamydial PID in turn often results in scarring or blockage of the tubes, making chlamydia one of the most common causes of female infertility and ectopic (tubal) pregnancy. Chlamydia also can lead to serious health consequences in infants born to infected mothers. Most infections initially are asymptomatic or cause outwardly trivial symptoms, which paradoxically increases the frequency and severity of long-term consequences by delaying diagnosis and treatment. As for all STDs associated with genital inflammation, chlamydia enhances susceptibility of infected persons to acquiring human immunodeficiency virus (HIV), contributing to the worldwide AIDS pandemic.
Lymphogranuloma
venereum (LGV) is a rare STD caused by particular strains of chlamydia
bacteria. LGV has made a recent comeback among MSM in industrialized
countries, but remains rare overall. Some strains of C. trachomatis
cause the blinding eye disease trachoma; as reflected in the scientific
name of the organism, trachoma was actually the first chlamydial
disease identified. The strains that cause trachoma are not sexually
transmitted, but are passed from person to person by flies, contaminated
clothing, or bedclothes, or by nonsexual person-to-person contact.
Historically, trachoma was one of the most common causes of blindness
worldwide and it remains an important public health problem in some
developing countries. Other related organisms, not transmitted
sexually, are C. pneumoniae, an occasional cause of respiratory infection, and C. psittaci, an infection of birds that sometimes causes pneumonia in humans.
This
Knol addresses sexually transmitted chlamydia in adults. The
information on frequency, risk factors, and populations at risk
emphasize the United States and is largely applicable to Western Europe,
Australia and New Zealand. However, routine diagnostic testing and
other prevention strategies have not been widely implemented in most
other countries, so that reliable epidemiologic data are scarce. Thus,
in most of the world the incidence, prevalence, and frequency of
complications is likely to be substantially higher than in the United
States, with the likely exception of some predominantly Islamic
countries. The information on symptoms, complications, treatment, and
prevention principles applies to all geographic areas.
HOW COMMON IS CHLAMYDIA AND WHO IS AT RISK?
Frequency
In
the United States and many industrialized countries, chlamydia cases
are routinely reported to health authorities, such as state or local
health departments. The US Centers for Disease Control and Prevention
(CDC) summarizes the annual data. Reported data, however, are
incomplete; many cases are not diagnosed at all and others are not
reported or counted. Therefore extrapolation and often creative
interpretation, as well as special research efforts, are needed to
estimate the actual infection rates. The incidence of chlamydia
(or any other disease) is the number of cases occurring over a
particular time, such as infections per year). The prevalence of
a condition is the number of cases that exist at any particular moment,
such as the percent of the population carrying the infection. Measures
of both incidence and prevalence are used to estimate the frequency of
chlamydia and other STDs.
This
graph shows the incidence of reported chlamydia in the United States
from 1987 to 2006. Slightly over 1 million cases were reported in 2006,
corresponding to 348 per 100,000 members of the population. After
adjusting for infections that go undiagnosed and for infections not
reported to health authorities, about 4 million new infections are
estimated to occur annually in the United States. The higher rate in
females compared with males in Figure 1 is more apparent than real,
because the data show reported infections, not actual case rates. More
women than men have regular chlamydia testing, so that more cases are
diagnosed; the actual incidence is about the same in both sexes. The
upward sloping curves in the figure are related more to increased
testing over time, and the rising frequency with which cases are
reported, than to actually rising rates of infection. http://www.cdc.gov/std/stats/trends2006.htm
The
bar graph illustrates the dramatic association of chlamydia with
younger age, especially in women and girls. For every 100,000 15- to
19-year-old girls in the United States, 2,863 (almost 3%) became
infected with chlamydia in 2006. Since only about 60% of teen girls are
sexually active, the adjusted rate approximates 4,500 per 100,000.
That is, almost 5% of sexually active teen girls nationwide acquire
chlamydia every year. Even this dramatic figure underestimates the rate
in some population groups. The rates vary widely between geographic
areas and by socioeconomic status and race/ethnicity; among minority
populations in some parts of the country, up to 30% of teens acquire
chlamydia each year. The rates undoubtedly are substantially higher in
most countries of Eastern Europe, Africa, and Asia.
The
overall frequency of chlamydia in the US has risen modestly in the past
decade, compared to apparent declines in the 1990s; a similar trend has
been observed in Sweden. There is controversy about the reasons, but
most experts attribute the changes to increased testing, use of
increasingly accurate diagnostic tests, and a true rise in incidence.
One theory suggests that improved case detection is having an unintended
side effect: because of earlier diagnosis and treatment of many
infections, people may develop less complete immunity to reinfection, so
that they remain more susceptible to repeat infection, possibly
resulting in a vicious circle of increased case rates as a paradoxical
consequence of improved prevention. Nationwide, in 1999-2002, at any
point in time 2% of all men and women were carrying chlamydia, including
4.6% of teen girls and 3.2% of 20-29 year old men. Among patients at
especially high risk, such as those obtaining health care at health
department STD clinics, typically 5-20% of patients are infected. Among
people with gonorrhea, 10% to 30% also have chlamydia. However, the
reverse is not true: among persons with chlamydia, fewer than 1% are
also infected with gonorrhea.
Transmission
Except
for the strains that cause trachoma, chlamydia is transmitted almost
exclusively by penile-vaginal or penile-anal sex. Despite common
beliefs to the contrary, chlamydia uncommonly infects the mouth or
throat, and unlike gonorrhea, transmission from an oral partner to the
genitals through fellatio or cunnilingus is rare, if it occurs at all.
Chlamydia is common among MSM, in whom it is transmitted predominantly
by penile-anal intercourse. Rectum to rectum transmission, through
fingers, sex toys, and shared douching equipment, probably accounts for
most LGV infections in MSM.
WHAT ARE THE SYMPTOMS AND SIGNS OF CHLAMYDIAL INFECTION?
The
hallmarks of chlamydial infection are symptoms that result directly
from infection of the urethra in men, the cervix and sometimes the
urethra in women, and the rectum of either men or women.
Urethral Infection in Men
Up
to half of men who acquire infection of the urethra remain
asymptomatic. When symptoms occur, they usually start 7-21 days after
exposure, although sometimes the infection shows up several weeks after
acquisition. Among men with symptoms, the most common clinical diagnosis is nongonococcal urethritis (NGU). The
main manifestations of NGU are abnormal discharge from the penis,
typically cloudy or white in color.
Sometimes there dysuria, i.e., discomfort in the penis when urinating,
which may range in severity from a minor sensation of itchiness in the
urethra to, rarely, severe pain.
The
name itself distinguishes NGU from gonorrhea, or gonococcal
urethritis. (The term nonspecific urethritis, or NSU, is used in some
countries for the same condition.) However, chlamydia accounts for only
20% to 40% of NGU cases. Some of the remainder are caused by the
sexually transmitted bacteria Mycoplasma genitalium and others might
result from specific strains of Ureaplasma urealyticum. Four percent to
5% of cases are due to herpes simplex virus, adenovirus, or Trichomonas
vaginalis. No known cause can be found for at least 30% to 40% of NGU
cases, although epidemiologic data support the notion that almost all
cases are sexually acquired. Most likely, as yet undiscovered bacteria
often are responsible. A few cases may be due to immunological causes
rather than infection per se. One theory is that prior infection with
chlamydia, gonorrhea or other organisms sometimes might stimulate an
aberrant immune response that causes symptoms in the absence of
continuing infection per se.
Genital Infection in Women
Up
to 80% of infected women remain asymptomatic, and when symptoms occur
they are mild and nonspecific; that is, infected women may notice
nothing different than normal day-to-day variations in the amount of
vaginal discharge and other minor genital discomfort. Women who notice
chlamydia symptoms typically experience increased vaginal discharge and
sometimes urinary urgency or discomfort on urination, sometimes
mimicking the symptoms of non-sexually transmitted urinary tract
infection. Spotty vaginal bleeding between menstrual periods, sometimes
triggered by sex, also is common, and some infected women experience
heavier than normal bleeding when they menstruate. Pain in the lower
abdomen indicates the development of PID, the main complication.
Examination
by an experienced clinician may reveal cervicitis, i.e., inflammatory
signs of the uterine cervix, such as increased redness or abnormal
discharge of mucus or pus from the cervical opening, sometimes
characterized as mucopurulent cervicitis (MPC), illustrated in the first
photo to the right. Gentle swabbing of the cervical opening may induce
bleeding (second photo). As with NGU in men, many infections other
than chlamydia cause MPC in women. Most cases of MPC are not associated
with known sexually transmitted organisms and, as for NGU, half the
time no infection at all can be identified as the cause.
Other Manifestations of Uncomplicated Chlamydial Infection
Most
infections of the rectum are asymptomatic, but some infected persons
notice discharge of mucus or pus from the anus, pain, itching of the
anus, and sometimes rectal bleeding. A few people with genital
chlamydia also have conjunctivitis, resulting in irritation, itching,
and other signs similar to “pink-eye”. Such cases probably result
primarily from auto-inoculation, i.e., self-infection after
contamination of the fingers with genital secretions.
Natural Course of Untreated Infection
Without
treatment, chlamydial infections can persist in the genital tract for
several months, sometimes a year or more, especially in women. The
longest proved case persisted 4 years, but rare infections might persist
even longer. Therefore, detection of chlamydia in a person who has not
been an apparent risk for STD—for example, a monogamous person or
someone who has not recently been sexually active—does not necessarily
mean a partner has been unfaithful or that the patient has not been
truthful about recent sexual activity. Nevertheless, the large majority
of infections apparently are cleared by the immune system within
several months, so that new infection usually indicates recent sexual
exposure to an infected partner.
Complications
Pelvic Inflammatory Disease. The main complication of chlamydia is PID, the result of lower genital tract chlamydia that migrates to the uterus and fallopian tubes. PID typically causes lower abdominal pain, sometimes with fever, and often abnormal vaginal bleeding, including both bleeding between periods and abnormally heavy menstruation. Severe cases can include abscesses of the Fallopian tubes or elsewhere in the lower abdomen, sometimes requiring surgery, including hysterectomy, for cure. Symptomatic PID is estimated to occur in 10% to 15% of women with chlamydia. PID is especially common with repeat chlamydial infection. Asymptomatic PID also is common, and chlamydia can be detected in the uterus of most infected women, usually without obvious illness, and many women who are infertile or who have an ectopic (tubal) pregnancy because chlamydia scarred their Fallopian tubes have no recollection of abdominal pain or other PID symptoms. Chlamydia is responsible for a large proportion, perhaps a majority, of tubal infertility and ectopic pregnancy cases in industrialized countries.
Epididymitis.
The most common chlamydia complication in men is acute epididymitis,
infection of the sperm collecting ducts and testicle; it is the male
counterpart of PID. Epididymitis results in painful enlargement of the
testicle, usually on one side only, often accompanied by fever and signs
of NGU, described above. Marked swelling and tenderness are the rule,
and epididymitis rarely explains mild forms of testicular pain or
discomfort. The photograph illustrates a typical case; the enlargement
of the right testicle is apparent.
Reactive Arthritis. Reactive arthritis is a relatively uncommon complication characterized by pain and swelling of certain joints, eye inflammation, a unique skin rash, and NGU in men or cervicitis in women. The NGU or cervicitis can be confusing to both patient and physician, since they can occur either from the initial chlamydial infection or as an immunologic reaction, part of the reactive arthritis syndrome itself. Reactive arthritis results from an abnormal immune response in susceptible individuals, triggered by any of several infections of the genital or gastrointestinal tract. Among sexually active young persons, chlamydia is the most common inciting infection.
Infection of the Newborn. The most common manifestation of transmission to the newborn from an infected mother is conjunctivitis (eye infection), often called ophthalmia neonatorum. Exposed infants also can develop chlamydial pneumonia or an asthma-like chronic bronchitis, with chronic cough persisting through several weeks or months of age. The occurrence of neonatal chlamydia represents a failure of prevention, since all pregnant women should be tested and, if infected, treated before delivery.
Lymphogranuloma Venereum. LGV has two forms. The “classical” version, occurring in both men and women, causes swelling and inflammation of the lymph nodes in the groin, sometimes progressing to rupture of the nodes and drainage of pus. Today, the most common version is infection of the rectum (proctitis) in MSM, often with severe pain, bleeding, and constipation. Modern LGV in MSM appears not to be transmitted by penile anal intercourse, and even with the modern resurgence of LGV, few MSM have been diagnosed with genital infection or with inflamed lymph nodes in the groin. These facts are consistent with rectum to rectum transmission, discussed above. Even with the recent resurgence in MSM, LGV remains rare.
HOW IS CHLAMYDIA DIAGNOSED?
Chlamydia
can be suspected by the trained clinician, based on symptoms and
physical examination. However, the findings are identical to those
caused by other genital, rectal, and abdominal infections. Further, the
physical examination often is entirely normal in patients with or
without symptoms. Therefore, laboratory testing is necessary for
definitive diagnosis.
Identification of Chlamydia trachomatis
The
main diagnostic method is to identify chlamydia at the site of
infection, usually after collecting a specimen on a swab or by testing
voided urine. Historically, cell culture was the preferred method,
i.e., to inoculate a specimen into cells that support the growth of
chlamydia bacteria, then identify chlamydia growing in the infected
cells. However, cell culture is cumbersome, time consuming, and
expensive; while still useful as a research tool, it is not a practical
method for widespread use. In the 1980s a brief period passed in which
tests were developed that used chemical methods to identify components
of the organism, or its DNA, in swab specimens. These tests were more
efficient than culture, but they were plagued by both false positive and
false negative test results.
The
past 15 years has seen the development of the current gold standard
assays, the nucleic acid amplification tests (NAAT). With NAAT, minute
quantities of DNA can be identified in clinical specimens. By designing
the test to identify a particular organism’s DNA, NAATs are both highly
sensitive, i.e., capable of detecting almost all chlamydial infections,
and highly specific, i.e., avoiding false positive results. The most
common and best known NAAT methodology is the polymerase chain reaction
(PCR), which is now used in a wide range of diagnostic tests for many
infectious diseases. Other NAAT methods include the ligase chain
reaction (LCR), the DNA strand displacement assay (SDA), and
transcription mediated analysis (TMA). One or more commercial tests to
detect chlamydia has been developed with each of these technologies. In
the United States, the predominant, currently available tests are based
on TMA (Aptima®, GenProbe), PCR (Amplicor®, Roche), or SDA (Probe-Tec®,
Becton Dickinson).
One
of the main advantages of NAAT compared with culture and other
diagnostic tests for chlamydia is that NAATs are accurate when used to
test voided urine or self-collected vaginal swabs. Therefore,
widespread screening of sexually active persons by NAAT can be carried
out without cumbersome pelvic examinations in women or painful passage
of swabs into men’s urethras. These characteristics make testing more
practical in clinics and physicians’ offices, and also allow performance
of screening tests in non-medical settings, such as schools, places of
employment, and even through the mail. In the future, NAAT kits may be
available for self-testing at home, as is now routine for pregnancy
testing. Recent research shows that the NAATs also give reliable
results when used to test rectal specimens, making the tests useful in
diagnosing chlamydia in MSM. Their performance for testing pharyngeal
(throat) specimens remains in question, but this is not an important
limitation; throat infection is uncommon and testing for it is rarely if
ever necessary. Today NAATs account for almost all testing for
chlamydia, as well as most testing for gonorrhea, in the United States
and other industrialized countries.
Blood Tests
Serology,
i.e., testing of blood for antibody produced by the immune system in
response to infection, has an important role in the diagnosis of many
infectious diseases. However, blood tests have little role in
diagnosing most chlamydial infections. Serological tests have been used
in research, and sometimes they are useful in diagnosing the underlying
cause of female infertility, by identifying women with Fallopian tube
obstruction due to chlamydia. Serology also is used to diagnose LGV
when NAAT testing of genital or rectal specimens does not reveal the LGV
strains of C. trachomatis, particularly in patients with chronic, longstanding infection.
HOW IS CHLAMYDIA TREATED?
Authorities
such as CDC and WHO recommend routine treatment when chlamydia is
suspected, without awaiting diagnostic confirmation. For example,
treatment against chlamydia is routine for the sex partners of infected
persons and for patients with MPC, NGU, proctitis, PID, or epididymitis,
before NAAT results are known. Similarly, because 10% to 30% of
persons with gonorrhea are co-infected, treatment of gonorrhea routinely
is accompanied by drugs active against chlamydia. Table 1 lists the
regimens recommended by CDC. http://www.cdc.gov/std/treatment/2006/toc.htm
Table 1. Treatment of Uncomplicated Chlamydial Infections in Nonpregnant Adults
Recommended Regimens
Azithromycin* 1.0 gram in a single oral dose
OR
Doxycycline+ 100 milligrams orally twice daily for 7 days
Alternative Regimens
Levofloxacin# 500 milligrams orally once daily for 7 days
OR
Ofloxacin@ 300 milligrams orally twice daily for 7 days
OR
Erythromycin+ 500 mg orally 4 times daily for 7 days
Recommended Regimens
Azithromycin* 1.0 gram in a single oral dose
OR
Doxycycline+ 100 milligrams orally twice daily for 7 days
Alternative Regimens
Levofloxacin# 500 milligrams orally once daily for 7 days
OR
Ofloxacin@ 300 milligrams orally twice daily for 7 days
OR
Erythromycin+ 500 mg orally 4 times daily for 7 days
* Zithromax® (Pfizer)
+ Many brands and generics
# Levaquin® (Ortho-McNeil)
@ Floxin (Ortho-McNeil)
+ Many brands and generics
# Levaquin® (Ortho-McNeil)
@ Floxin (Ortho-McNeil)
Antibiotics
Routine Treatment. The two primary drug classes used for treatment of chlamydia are the macrolide antibiotics and the tetracyclines. The former group includes azithromycin (Zithromax®), clarithromycin (Biaxin®), erythromycin (many generic brands), and others.
The tetracyclines include doxycycline (Vibramycin® and generics),
minocycline (Minocin® and generics), and tetracycline itself. In most
industrialized countries, the primary treatments recommended by CDC,
WHO, and various health departments are either a single oral dose of
azithromycin, 1.0 gram, or doxycycline, usually in a dose of 100
milligrams (0.1 gram) by mouth, twice daily for 7 days. Either regimen
is at least 95% effective (often 99% effective) in curing uncomplicated
chlamydia.
Alternative Drugs.
Levofloxacin (Levaquin®) or other drugs of the fluoroquinolone class
sometimes are used when azithromycin or doxycycline cannot be given, or
when treatment must be started and the exact cause of the patient’s
condition is not known, as when chlamydia and urinary tract infection
both are possible explanations for the patient’s infection. However,
not all fluoroquinolones are useful against chlamydia. For example,
ciprofloxacin (Cipro®) is not effective. The tetracyclines should not
be used in pregnant women; erythromycin or amoxicillin are recommended
as alternatives to treat pregnant women if azithromycin is not available
or not tolerated. PID and epididymitis are treated with combinations
of drugs, designed to eradicate gonorrhea and various other bacteria
that can cause or contribute to the infection.
Treatment of Sex Partners
The Importance of Partner Treatment.
The sex partners of persons with chlamydia require treatment to protect
their own health and that of other sex partners who might be at risk.
All STDs are selectively transmitted by infected persons without
symptoms. Many persons with genital discharge or other symptoms
recognize the health implications, stop having sex, and seek care. By
contrast, those without symptoms have no awareness of the risk and
continue sexual activity. Therefore, the person responsible for a
particular patient’s chlamydia is not likely to have symptoms that lead
him or her to seek health care. This principle underlies a central
tenet of STD prevention: infected patients and their health care
providers must take active steps to inform partners and assure
treatment. With few exceptions, local or state health departments in
the United States, as well as their counterparts in other countries,
lack the resources to assist in notifying the partners of persons with
chlamydia or gonorrhea. Therefore, assuring treatment of partners is
the responsibility of the infected person and the health care provider.
Ideally,
the partners should be professionally examined and counseled before
being treated. However, many patients are unable or unwilling to
contact the partners who they believe infected them. Other partners
cannot be located or contacted, and still others do not seek care
despite being informed, often because they do not believe they are
infected, especially if they have no STD symptoms. Accordingly, it is
likely that through these routine approaches, only about half of all
partners of persons with chlamydia or gonorrhea receive timely
treatment. The remainder help to sustain the chlamydia epidemic, and
they often re-infect the original patient.
Expedited Partner Treatment.
The concept of expedited partner treatment (EPT) has evolved in recent
years to address the difficulty of assuring that partners receive
treatment. Under EPT—also known as patient-delivered partner therapy,
or PDPT—infected patients are given extra drug or a prescription to be
taken to their sex partners, without requiring partners to visit a
provider’s office or clinic. Other mechanisms also can be employed,
such as direct retrieval of medication by the partner from the
provider’s office (without examination) or from a pharmacy. Three
randomized, controlled clinical trials among persons with chlamydia or
gonorrhea have demonstrated that EPT results in substantially more
partners receiving treatment in comparison with historically routine
partner management, i.e., notifying partners to attend for personal
evaluation. Most important, all three trials showed that reinfection of
the initially infected person was less frequent with EPT than with
routine management.
Even
before the research trials were conducted, EPT had been used frequently
by health care providers in the United States and elsewhere, as a
pragmatic accommodation to assure partner treatment and to protect their
patients from reinfection. CDC and other authorities now recommend EPT
as a routine option to assure treatment of the partners of heterosexual
men and women with chlamydia or gonorrhea. http://www.cdc.gov/std/ept/
Health authorities have hesitated to recommend routine use of EPT among
MSM, who tend to have higher rates of other STDs, especially
undiagnosed HIV infection, along with their gonorrhea or chlamydial
infections. However, EPT remains an option when other methods to assure
partner treatment are not likely to be successful.
Follow-up Testing
Test of Cure.
The recommended treatments are sufficiently reliable that routine
retesting to assure cure generally is not necessary. However, test of
cure is recommended in pregnant women, both because the risk of
treatment failure is elevated and because the consequences of
inadequately treated infection may be severe. Tests of cure also are
recommended for infected persons who might be unable to comply with the
complete course of treatment or if atypical antibiotic regimens are
used. Tests of cure should be done 3 weeks or more after completion of
treatment. Earlier testing risks false positive results, because NAATs
can detect chlamydial DNA up to 2-3 weeks after the organism has been
killed, resulting in false positive test results.
Rescreening.
Although routine test of cure is generally not recommended for persons
treated for chlamydia or gonorrhea, CDC and other health agencies now
recommend “rescreening” in its place. Rescreening means delayed
retesting of infected persons, i.e. a few months after treatment. Among
men and women with either chlamydia or gonorrhea, 10% to 20% are found
to be infected again when tested 3-6 months later. Most cases result
from reinfection, either from an untreated partner or by sex with other
partners. However, some cases represent persistent infection, despite
normally effective antibiotic treatment; in these cases, rescreening
serves the same role as earlier test of cure. Rescreening 3 months
after treatment is advised for all patients with chlamydia or gonorrhea,
regardless of the patients’ certainty that their partners were treated,
whether or not condoms were used for sex following treatment, and
whether or not their current sex partners are believed to be at risk.
HOW IS CHLAMYDIA PREVENTED AND CONTROLLED?
Prevention
and control of STD can be viewed from the perspective of the individual
at risk, who prefers to avoid infection (or, if infected, to prevent
complications); and from the perspective of health care providers and
prevention agencies, such as health departments. These strategies have
considerable overlap. For example, health care providers are advised to
routinely test patients at risk for chlamydia, but sexually active
persons can request testing when the provider does not take the
initiative. Similarly, providers should promote condom use, but only
persons at risk can choose to use them.
Public Health Prevention Strategies
The
mainstay of chlamydia prevention is laboratory-based screening, i.e.,
routine testing of persons at risk. Because most infections are
asymptomatic, case finding cannot rely on attendance by persons in
health care providers’ offices or clinics. Owing to the high frequency
of chlamydia in all sexually active populations, screening
recommendations are not even based on indicators of STD risk, such as
number of sex partners or new sexual partnerships. Rather, CDC and
other health agencies recommend routine testing by NAAT for all women
age 25 and under who are sexually active (including monogamous women)
whenever they seek health care for any reason. Laboratory screening of
men theoretically would contribute to control, but widespread male
screening is difficult because outwardly healthy young men do not
frequently visit health care providers. However, screening tests for
men are useful when those at risk can be readily accessed, such as men
who are incarcerated, military recruits, and sometimes in schools.
In
addition to diagnostic screening tests, important public health
chlamydia prevention strategies include promulgation and use of
recommended treatment regimens, assuring treatment of infected persons’
sex partners, counseling and education programs, professional education
of health care providers in clinical management and prevention, and
surveillance through required reporting of infections to local and state
health departments, which in turn permits the efficient targeting of
prevention resources where needed.
Personal Prevention
Consistent
use of condoms for vaginal or anal intercourse outside committed,
mutually monogamous relationships is a core prevention strategy for all
STDs and HIV infection. Chlamydia is no exception. No sexually
transmitted pathogen passes through an intact condom, and properly used
condoms—i.e., placement prior to genital penetration, with prompt
removal after sex, before erection is lost—are almost 100% effective.
(Apparent failures in preventing chlamydia are due mostly to improper
use or condom rupture, not to actual failures of intact condoms.)
Specific sexual practices also influence the risk of STD. Unprotected
vaginal and anal sex risks transmission from either partner to the
other. Chlamydia is rarely if ever transmitted in either direction by
cunnilingus or fellatio, even though these practices confer modest risk
for gonorrhea, herpes, and syphilis. In general, however, unprotected
oral-genital sex carries substantially lower risk for transmission of
STDs, including HIV, than unprotected vaginal or anal intercourse.
Selecting
sex partners at low risk is important as well in preventing chlamydia
and other STDs. Potential partners at especially high risk are
commercial sex workers, persons believed to have multiple partners
combined with inconsistent condom use, and users of illicit drugs.
Intuitively, having fewer sex partners enhances sexual safety while
increased partner numbers increases the risk of chlamydia and all STDs.
However, partner number per se is less a risk factor than how and where
partners are selected and whether or not condoms are consistently
used. Sexually active persons outside mutually monogamous
relationships, especially teens and young adults, periodically should
seek routine screening tests for chlamydia and other common STDs,
especially gonorrhea, syphilis, HIV, and sometimes genital herpes. The
frequency of recommended screening depends on risk. Annual testing
makes sense for most sexually active young persons, but some—such as MSM
with multiple partners, sexually active teens, and commercial sex
workers—should be tested as often as 2-4 times per year. Finally, all
sexually active persons should be aware of the common symptoms of STD
and promptly seek care when such health problems appear, either in
themselves or their sex partners.
SUGGESTED READING
1. Stamm WE. Chlamydia trachomatis Infections of the Adult. Chapter 32 in Holmes KK, et al (ed). Sexually Transmitted Diseases, 4th edition. New York, McGraw-Hill, 2008:575-93. The main chapter in the premier STD textbook, by one of the world's top experts in chlamydial infections.
2.
Handsfield HH. Color Atlas and Synopsis of Sexually Transmitted
Diseases, 2nd edition. Chapter 2, Chlamydial Infections. New York,
McGraw-Hill, 2001:12-19. A
succinct overview with extensive clinical photographs illustrating
symptoms, intended for health professionals but easily understood by
educated readers.
3. Datta SD, et al. Gonorrhea and chlamydia in the United States among Persons 14 to 39 Years of Age, 1999 to 2002. Annals of Internal Medicine 2007;147:89-96. The report of the most comprehensive national survey of these STDs in the US.
4. CDC. Sexually Transmitted Disease Surveillance, 2006. Atlanta, GA, November 2007. http://www.cdc.gov/std/stats/trends2006.htm Annually updated statistics on reported STD in the US.
5. CDC. Sexually Transmitted Diseases Treatment Guidelines, 2006. Morbidity and Mortality Weekly Report 2006;55:RR-11. http://www.cdc.gov/std/treatment/2006/toc.htm CDC's treatment recommendations, supplemented by extensive summaries of key information about all STDs.
6. CDC. Expedited Partner Therapy in the Management of Sexually Transmitted Diseases, 2006. http://www.cdc.gov/std/ept/ CDC's
summary of outcomes of research studies and recommendations use of
streamlined approaches to assure that partners of persons with gonorrhea
or chlamydia receive treatment.
7. Brunham RC, et al. The unexpected impact of a Chlamydia trachomatis control program on susceptibility to reinfection. Journal of Infectious Diseases 2005;192:1836-44. A
thoughtful analysis of why chlamydia rates might be rising despite
intensive prevention, suggesting that earlier treatment reduces
immunity, leaving persons susceptible to reinfection.
8.
Golden MR, et al. Impact of expedited sex partner treatment on
recurrent or persistent gonorrhea or chlamydial infection: a randomized
controlled trial. New England Journal of Medicine 2005;352:676-85. The most comprehensive of three research studies documenting the effectiveness of streamlined treatment of sex partners.
9. Handsfield HH. Nongonococcal urethritis: a few answers but mostly questions (editorial). Journal of Infectious Diseases 2006;193:333-5. A succinct summary of the causes of NGU and the remaining uncertainties about the syndrome.
10. Scholes D, et al. Prevention of pelvic inflammatory disease by screening for cervical chlamydial infection. New England Journal of Medicine 1996;334:1362–1366. The primary research study documenting that routine testing prevents the most important complication of chlamydia.
11.
Marrazzo JM, et al. Impact of patient characteristics on performance
of nucleic acid amplification tests and DNA probe for detection of Chlamydia trachomatis in women with genital infections. Journal of Clinical Microbiology 2005;4:577-84. The science behind the modern tests for chlamydia.