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Chlamydia, or more specifically a chlamydia infection, is a sexually transmitted infection caused by the bacterium Chlamydia trachomatis.<ref name=CDCStats2015/> Most people who are infected have no symptoms.<ref name=CDCFact2016/> When symptoms do appear, they may occur only several weeks after infection;<ref name=CDCFact2016/> the incubation period between exposure and being able to infect others is thought to be on the order of two to six weeks.<ref>Template:Cite book</ref> Symptoms in women may include vaginal discharge or burning with urination.<ref name=CDCFact2016/> Symptoms in men may include discharge from the penis, burning with urination, or pain and swelling of one or both testicles.<ref name=CDCFact2016/> The infection can spread to the upper genital tract in women, causing pelvic inflammatory disease, which may result in future infertility or ectopic pregnancy.<ref name="CDC2015">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Chlamydia infections can occur in other areas besides the genitals, including the anus, eyes, throat, and lymph nodes. Repeated chlamydia infections of the eyes that go without treatment can result in trachoma, a common cause of blindness in the developing world.<ref name="CDC2009Eye">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Chlamydia can be spread during vaginal, anal, oral, or manual sex and can be passed from an infected mother to her baby during childbirth.<ref name="CDCFact2016">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite book</ref> The eye infections may also be spread by personal contact, flies, and contaminated towels in areas with poor sanitation.<ref name=CDC2009Eye/> Infection by the bacterium Chlamydia trachomatis only occurs in humans.<ref>Template:Cite book</ref> Diagnosis is often by screening, which is recommended yearly in sexually active women under the age of 25, others at higher risk, and at the first prenatal visit.<ref name=CDCFact2016/><ref name=CDC2015/> Testing can be done on the urine or a swab of the cervix, vagina, or urethra.<ref name=CDC2015/> Rectal or mouth swabs are required to diagnose infections in those areas.<ref name=CDC2015/>
Prevention is by not having sex, the use of condoms, or having sex with only one other person, who is not infected.<ref name=CDCFact2016/> Chlamydia can be cured by antibiotics, with typically either azithromycin or doxycycline being used.<ref name=CDC2015/> Erythromycin or azithromycin is recommended in babies and during pregnancy.<ref name=CDC2015/> Sexual partners should also be treated, and infected people should be advised not to have sex for seven days and until symptom free.<ref name=CDC2015/> Gonorrhea, syphilis, and HIV should be tested for in those who have been infected.<ref name=CDC2015/> Following treatment, people should be tested again after three months.<ref name=CDC2015/>
Chlamydia is one of the most common sexually transmitted infections, affecting about 4.2% of women and 2.7% of men worldwide.<ref name="New2015">Template:Cite journal</ref><ref name="WHO2015Fact">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In 2015, about 61 million new cases occurred globally.<ref name="GBD2015Pre">Template:Cite journal</ref> In the United States, about 1.4 million cases were reported in 2014.<ref name="CDCStats2015">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Infections are most common among those between the ages of 15 and 25 and are more common in women than men.<ref name=CDC2015/><ref name=CDCStats2015/> In 2015, infections resulted in about 200 deaths.<ref name="GBD2015De">Template:Cite journal</ref> The word chlamydia is from the Greek {{#invoke:Lang|lang}}, meaning 'cloak'.<ref>Template:Cite book</ref><ref>Template:Cite journal</ref> Template:TOC limit
Signs and symptomsEdit
Genital diseaseEdit
WomenEdit
Chlamydial infection of the cervix (neck of the womb) is a sexually transmitted infection which has no symptoms for around 70% of women infected. The infection can be passed through vaginal, anal, oral, or manual sex. Of those who have an asymptomatic infection that is not detected by their doctor, approximately half will develop pelvic inflammatory disease (PID), a generic term for infection of the uterus, fallopian tubes, and/or ovaries. PID can cause scarring inside the reproductive organs, which can later cause serious complications, including chronic pelvic pain, difficulty becoming pregnant, ectopic (tubal) pregnancy, and other dangerous complications of pregnancy.<ref name="pmid28835360"/>
Chlamydia is known as the "silent epidemic", as at least 70% of genital C. trachomatis infections in women (and 50% in men) are asymptomatic at the time of diagnosis,<ref name="NHS Chlamydia page">NHS Chlamydia page Template:Webarchive</ref> and can linger for months or years before being discovered. Signs and symptoms may include abnormal vaginal bleeding or discharge, abdominal pain, painful sexual intercourse, fever, painful urination or the urge to urinate more often than usual (urinary urgency).<ref name="pmid28835360">Template:Cite journal</ref>
For sexually active women who are not pregnant, screening is recommended in those under 25 and others at risk of infection.<ref name="AmFamPhys">Template:Cite journal</ref> Risk factors include a history of chlamydial or other sexually transmitted infection, new or multiple sexual partners, and inconsistent condom use.<ref name="USPSTF">Template:Cite journal</ref> Guidelines recommend all women attending for emergency contraceptive are offered chlamydia testing, with studies showing up to 9% of women aged under 25 years had chlamydia.<ref>Template:Cite journal</ref>
MenEdit
In men, those with a chlamydial infection show symptoms of infectious inflammation of the urethra in about 50% of cases.<ref name="NHS Chlamydia page"/> Symptoms that may occur include: a painful or burning sensation when urinating, an unusual discharge from the penis, testicular pain or swelling, or fever. If left untreated, chlamydia in men can spread to the testicles causing epididymitis, which in rare cases can lead to sterility if not treated.<ref name="NHS Chlamydia page"/> Chlamydia is also a potential cause of prostatic inflammation in men, although the exact relevance in prostatitis is difficult to ascertain due to possible contamination from urethritis.<ref name="urology">Template:Cite journal</ref>
Eye diseaseEdit
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Trachoma is a chronic conjunctivitis caused by Chlamydia trachomatis.<ref name=":0">Template:Cite book</ref> It was once the leading cause of blindness worldwide, but its role diminished from 15% of blindness cases by trachoma in 1995 to 3.6% in 2002.<ref name="WHO1995">Template:Cite journal</ref><ref name="WHO2002">Template:Cite journal</ref> The infection can be spread from eye to eye by fingers, shared towels or cloths, coughing and sneezing and eye-seeking flies.<ref name="LancetTrachoma">Template:Cite journal</ref> Symptoms include mucopurulent ocular discharge, irritation, redness, and lid swelling.<ref name=":0" /> Newborns can also develop chlamydia eye infection through childbirth (see below). Using the SAFE strategy (acronym for surgery for in-growing or in-turned lashes, antibiotics, facial cleanliness, and environmental improvements), the World Health Organization aimed (unsuccessfully) for the global elimination of trachoma by 2020 (GET 2020 initiative).<ref name="GET2020">World Health Organization. Trachoma Template:Webarchive. Accessed March 17, 2008.</ref><ref name="LancetSAFE">Template:Cite journal</ref> The updated World Health Assembly neglected tropical diseases road map (2021–2030) sets 2030 as the new timeline for global elimination.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
JointsEdit
Chlamydia may also cause reactive arthritis—the triad of arthritis, conjunctivitis and urethral inflammation—especially in young men. About 15,000 men develop reactive arthritis due to chlamydia infection each year in the U.S., and about 5,000 are permanently affected by it. It can occur in both sexes, though is more common in men.Template:Citation needed
InfantsEdit
As many as half of all infants born to mothers with chlamydia will be born with the disease. Chlamydia can affect infants by causing spontaneous abortion; premature birth; conjunctivitis, which may lead to blindness; and pneumonia.<ref name="CDC">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Conjunctivitis due to chlamydia typically occurs one week after birth (compared with chemical causes (within hours) or gonorrhea (2–5 days)).<ref>Template:Citation</ref>
Other conditionsEdit
A different serovar of Chlamydia trachomatis is also the cause of lymphogranuloma venereum, an infection of the lymph nodes and lymphatics. It usually presents with genital ulceration and swollen lymph nodes in the groin, but it may also manifest as rectal inflammation, fever or swollen lymph nodes in other regions of the body.<ref name="proctitis">Template:Cite journal</ref>
TransmissionEdit
Chlamydia can be transmitted during vaginal, anal, oral, or manual sex or direct contact with infected tissue such as conjunctiva. Chlamydia can also be passed from an infected mother to her baby during vaginal childbirth.<ref name=CDC/> It is assumed that the probability of becoming infected is proportionate to the number of bacteria one is exposed to.<ref>Template:Cite journal</ref>
PathophysiologyEdit
Chlamydia bacteria have the ability to establish long-term associations with host cells. When an infected host cell is starved for various nutrients such as amino acids (for example, tryptophan),<ref name="pmid17724071">Template:Cite journal</ref> iron, or vitamins, this has a negative consequence for chlamydia bacteria since the organism is dependent on the host cell for these nutrients. Long-term cohort studies indicate that approximately 50% of those infected clear within a year, 80% within two years, and 90% within three years.<ref name="Fairley2007">Template:Cite journal</ref>
The starved chlamydia bacteria can enter a persistent growth state where they stop cell division and become morphologically aberrant by increasing in size.<ref name="pmid16338585">Template:Cite journal</ref> Persistent organisms remain viable as they are capable of returning to a normal growth state once conditions in the host cell improve.<ref>Template:Cite book</ref>
There is debate as to whether persistence has relevance: some believe that persistent chlamydia bacteria are the cause of chronic chlamydial diseases. Some antibiotics such as β-lactams have been found to induce a persistent-like growth state.<ref name="bayramova2018insight">Template:Cite journal</ref><ref name="klockner2016deconstructing">Template:Cite book</ref>
DiagnosisEdit
The diagnosis of genital chlamydial infections evolved rapidly from the 1990s through 2006. Nucleic acid amplification tests (NAAT), such as polymerase chain reaction (PCR), transcription mediated amplification (TMA), and the DNA strand displacement amplification (SDA) now are the mainstays. NAAT for chlamydia may be performed on swab specimens sampled from the cervix (women) or urethra (men), on self-collected vaginal swabs, or on voided urine.<ref>Template:Cite journal</ref> NAAT has been estimated to have a sensitivity of approximately 90% and a specificity of approximately 99%, regardless of sampling from a cervical swab or by urine specimen.<ref name="Haugland2010">Template:Cite journal</ref> In women seeking treatment in a sexually transmitted infection clinic where a urine test is negative, a subsequent cervical swab has been estimated to be positive in approximately 2% of the time.<ref name=Haugland2010/>
At present, the NAATs have regulatory approval only for testing urogenital specimens, although rapidly evolving research indicates that they may give reliable results on rectal specimens.
Because of improved test accuracy, ease of specimen management, convenience in specimen management, and ease of screening sexually active men and women, the NAATs have largely replaced culture, the historic gold standard for chlamydia diagnosis, and the non-amplified probe tests. The latter test is relatively insensitive, successfully detecting only 60–80% of infections in asymptomatic women, and often giving falsely-positive results. Culture remains useful in selected circumstances and is currently the only assay approved for testing non-genital specimens. Other methods also exist including: ligase chain reaction (LCR), direct fluorescent antibody resting, enzyme immunoassay, and cell culture.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
The swab sample for chlamydial infections does not show difference whether the sample was collected in home or in clinic in terms of numbers of patient treated. The implications in cured patients, reinfection, partner management, and safety are unknown.<ref>Template:Cite journal</ref>
Rapid point-of-care tests are, as of 2020, not thought to be effective for diagnosing chlamydia in men of reproductive age and non-pregnant women because of high false-negative rates.<ref>Template:Cite journal</ref>
PreventionEdit
Prevention is by not having sex, the use of condoms, or having sex with only one other person, who is not infected.<ref name=CDCFact2016/>
ScreeningEdit
For sexually active women who are not pregnant, screening is recommended in those under 25 and others at risk of infection.<ref name="AmFamPhys"/> Risk factors include a history of chlamydial or other sexually transmitted infection, new or multiple sexual partners, and inconsistent condom use.<ref name="USPSTF"/> For pregnant women, guidelines vary: screening women with age or other risk factors is recommended by the U.S. Preventive Services Task Force (USPSTF) (which recommends screening women under 25) and the American Academy of Family Physicians (which recommends screening women aged 25 or younger). The American College of Obstetricians and Gynecologists recommends screening all at risk, while the Centers for Disease Control and Prevention recommend universal screening of pregnant women.<ref name="AmFamPhys"/> The USPSTF acknowledges that in some communities there may be other risk factors for infection, such as ethnicity.<ref name="AmFamPhys"/> Evidence-based recommendations for screening initiation, intervals and termination are currently not possible.<ref name="AmFamPhys"/> For men, the USPSTF concludes evidence is currently insufficient to determine if regular screening of men for chlamydia is beneficial.<ref name="USPSTF"/> They recommend regular screening of men who are at increased risk for HIV or syphilis infection.<ref name="USPSTF"/> A Cochrane review found that the effects of screening are uncertain in terms of chlamydia transmission but that screening probably reduces the risk of pelvic inflammatory disease in women.<ref>Template:Cite journal</ref>
In the United Kingdom the National Health Service (NHS) aims to:
- Prevent and control chlamydia infection through early detection and treatment of asymptomatic infection;
- Reduce onward transmission to sexual partners;
- Prevent the consequences of untreated infection;
- Test at least 25 percent of the sexually active under 25 population annually.<ref>{{#invoke:citation/CS1|citation
|CitationClass=web }}</ref>
- Retest after treatment.<ref name="DesaiWoodhall2015">Template:Cite journal</ref>
TreatmentEdit
C. trachomatis infection can be effectively cured with antibiotics. Guidelines recommend azithromycin, doxycycline, erythromycin, levofloxacin or ofloxacin.<ref>Template:Cite book</ref> In men, doxycycline (100 mg twice a day for 7 days) is probably more effective than azithromycin (1 g single dose) but evidence for the relative effectiveness of antibiotics in women is very uncertain.<ref>Template:Cite journal</ref> Agents recommended during pregnancy include erythromycin or amoxicillin.<ref name="CDC2015" /><ref name="urlDiagnosis and Treatment of Chlamydia trachomatis Infection - April 15, 2006 - American Family Physician">Template:Cite journal</ref>
An option for treating sexual partners of those with chlamydia or gonorrhea includes patient-delivered partner therapy (PDT or PDPT), which is the practice of treating the sex partners of index cases by providing prescriptions or medications to the patient to take to his/her partner without the health care provider first examining the partner.<ref name="EPTFinalReport2006">Expedited Partner Therapy in the Management of Sexually Transmitted Diseases (2 February 2006) Template:Webarchive U.S. Department of Health and Human Services Public Health Service. Centers for Disease Control and Prevention National Center for HIV, STD, and TB Prevention</ref>
Following treatment people should be tested again after three months to check for reinfection.<ref name=CDC2015/> Test of cure may be false-positive due to the limitations of NAAT in a bacterial (rather than a viral) context, since targeted genetic material may persist in the absence of viable organisms.<ref name="toc">Template:Cite journal</ref>
EpidemiologyEdit
Globally, as of 2015, sexually transmitted chlamydia affects approximately 61 million people.<ref name=GBD2015Pre/> It is more common in women (3.8%) than men (2.5%).<ref name="LancetEpi2012">Template:Cite journal</ref> In 2015 it resulted in about 200 deaths.<ref name=GBD2015De/>
In the United States about 1.6 million cases were reported in 2016.<ref name=CDC2016Stat/> The CDC estimates that if one includes unreported cases there are about 2.9 million each year.<ref name="CDC2016Stat">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> It affects around 2% of young people.<ref>Template:Cite journal</ref> Chlamydial infection is the most common bacterial sexually transmitted infection in the UK.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Chlamydia causes more than 250,000 cases of epididymitis in the U.S. each year. Chlamydia causes 250,000 to 500,000 cases of PID every year in the United States. Women infected with chlamydia are up to five times more likely to become infected with HIV, if exposed.<ref name=CDC/>
See alsoEdit
ReferencesEdit
External linksEdit
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