Chlamydia is the most frequently reported notifiable disease in the United States, with the CDC recording 1.65 million cases in 2022. Caused by the obligate intracellular bacterium Chlamydia trachomatis, the infection is largely silent — roughly 70% of cervical infections in women and 50% of male urethral infections produce no symptoms — which is why women under 25 are screened annually regardless of symptoms.
Chlamydia infection (ICD-10: A56) is a sexually transmitted bacterial infection caused by Chlamydia trachomatis serovars D through K, which selectively infect columnar epithelium of the urogenital tract, rectum, pharynx, and conjunctiva. The organism is an obligate intracellular pathogen with a unique biphasic lifecycle: the elementary body (infectious form) enters epithelial cells, transforms into the metabolically active reticulate body that divides within an inclusion, and re-differentiates into elementary bodies that are released to infect adjacent cells. This intracellular biology explains the slow tempo of symptoms (1-3 weeks after exposure), the prolonged carriage, and the need for antibiotics that achieve intracellular concentrations. Clinical presentations include urethritis, cervicitis, proctitis, pharyngitis, conjunctivitis, lymphogranuloma venereum (LGV — caused by serovars L1-L3), neonatal conjunctivitis and pneumonia, and the post-infectious reactive arthritis syndrome.
The key symptoms of Chlamydia Infection are: Most infections cause no symptoms — 70% of cervical infections in women and 50% of male urethral infections are silent, persisting for months without notice., Mild, often clear or whitish urethral discharge in symptomatic men, appearing 1-3 weeks after exposure and easily mistaken for a minor irritation., Dysuria (burning on urination) in men and women, typically less intense than the dysuria of gonorrhea or urinary tract infection., Increased vaginal discharge in women, sometimes mucopurulent, often noticed alongside intermenstrual bleeding or post-coital bleeding., Lower abdominal or pelvic pain in women — a warning sign of ascension to pelvic inflammatory disease and reason for urgent evaluation., Dyspareunia (painful intercourse) and cervical motion tenderness on bimanual exam, both features of cervicitis or early PID., Rectal pain, mucus discharge, tenesmus, or bleeding in symptomatic rectal chlamydia, though most rectal infections are asymptomatic..
Diagnosis relies on nucleic acid amplification testing (NAAT), which has displaced culture and antigen detection due to sensitivity exceeding 95% and specificity exceeding 99% across all anatomic sites. Specimen choice depends on patient and site: first-catch urine in men, vaginal or endocervical swab in women, and self- or clinician-collected pharyngeal and rectal swabs in MSM and in any patient with relevant exposure. CDC recommends extragenital (pharyngeal and rectal) testing in MSM and in any patient who reports oral or anal sex. Self-collected swabs are accurate and acceptable to most patients. Culture is now reserved for medicolegal cases (sexual assault evaluation), suspected antimicrobial treatment failure, and research; routine clinical management uses NAAT. Lymphogranuloma venereum requires identification of L1-L3 serovars through PCR genotyping or specific LGV-typing assays, available through state public health labs. Every chlamydia diagnosis should trigger bundled testing for gonorrhea, syphilis, HIV, and hepatitis B and C at the same visit, since 10-30% of patients have a second concurrent STI. CDC recommends annual screening of all sexually active women under 25, women over 25 with risk factors, MSM at all anatomic sites every 3-6 months, and pregnant individuals at the first prenatal visit. Repeat NAAT 3 months after treatment is recommended for all patients to detect reinfection, the dominant cause of "recurrent" chlamydia. Test of cure is not routinely needed for urogenital chlamydia treated with doxycycline but is recommended in pregnancy, persistent symptoms, suspected non-adherence, and after alternative regimens. Public health reporting is mandatory in all US states.
With doxycycline 7-day therapy, the prognosis for uncomplicated urogenital, rectal, and pharyngeal chlamydia is excellent — microbiologic cure in 95-100% of cases. Single-dose azithromycin cures 95% of urogenital infections but only 80-85% of rectal infections, which is why doxycycline is now first-line. Pelvic inflammatory disease responds clinically in over 90% of cases with appropriate antibiotic therapy, but tubal scarring still develops in roughly 12% of women after a single PID episode, 25% after two episodes, and 50% after three. The corresponding rises in ectopic pregnancy (6-7 fold) and tubal-factor infertility are the dominant long-term consequences. Reactive arthritis, when it develops, peaks 1-3 weeks after the acute infection, is more common in HLA-B27 carriers, and resolves over 3-6 months in most cases; a minority become chronic. LGV strictures and fistulas are largely preventable with prompt 21-day doxycycline. Reinfection is the dominant cause of recurrence — 15-25% within 12 months in high-risk populations — and reflects ongoing exposure rather than antibiotic failure. The decisive prognostic factor at the population level is screening uptake: the more sexually active young women receive annual screening, the lower the PID and infertility burden.
Infectious disease consultation is warranted in suspected LGV, severe or treatment-refractory pelvic inflammatory disease, complicated neonatal disease, pregnancy with macrolide or amoxicillin intolerance, and recurrent infection despite adequate treatment. Most uncomplicated cases are managed by primary care and sexual health clinics according to CDC algorithms.
Find specialists →Urethral and vaginal symptoms typically resolve within 5-10 days of starting doxycycline. Sexual activity should be avoided for 7 days after completing the regimen and until partners are treated. PID pain and fever resolve over 3-7 days with appropriate antibiotics. LGV inguinal lymphadenopathy responds over 2-4 weeks of doxycycline; bubo resolution may take 2-3 months. Retest at 3 months for reinfection; test of cure is not routinely needed for doxycycline-treated urogenital cases but is recommended in pregnancy and after alternative regimens.
No specific restrictions for uncomplicated chlamydia. With pelvic inflammatory disease, rest until pain and fever resolve, then gradually return to normal activity. With reactive arthritis, avoid weight-bearing exercise on affected joints until inflammation settles.
Choose a clinician familiar with the CDC 2021 STI Treatment Guidelines, with access to NAAT testing at all relevant anatomic sites (urine, vaginal, pharyngeal, rectal), who prescribes doxycycline-first (with appropriate exceptions), and who integrates bundled STI screening at every visit. Sexual health clinics typically offer rapid testing, partner notification support, and expedited partner therapy where legal.
Medically reviewed by AIHealz Medical Editorial Board · May 13, 2026
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