This bacterial organism colonizes multiple mucosal surfaces, including the urethra, vaginal canal, cervix, rectum, and pharyngeal tissue [1]. Ocular manifestations originate from recurrent conjunctival colonization typically initiated during early childhood [2]. Microbiological investigations indicate potential interactions with resident cervical and vaginal microbial communities, though meta-analytical data on diversity shifts remain inconsistent [3].
Disease overview
BacterialChlamydia trachomatis infection
沙眼衣原体感染
Evidence-backed informationEN 5/7 applicable sections · ZH 5/7 applicable sectionsUpdated Sep 3, 2026
Chlamydia trachomatis infection constitutes a substantial global health burden, recognized as the most frequently identified bacterial sexually transmitted infection worldwide [1]. The pathogen also causes trachoma, which remains the foremost infectious etiology of blindness internationally [2]. Clinical presentation is frequently silent, with asymptomatic carriage exceeding eighty percent of cases [1].
Read the full clinical and epidemiological profile6
The majority of infected individuals exhibit no overt symptoms [1]. Genital involvement in females may progress to upper tract inflammation, elevating susceptibility to ectopic gestation, tubal factor infertility, and persistent pelvic discomfort [1]. Male presentations frequently encompass epididymal inflammation and rectal mucosal disease [1]. Ocular disease evolves from acute conjunctival inflammation to progressive scarring and eyelash malposition [2].
Global health monitoring consistently ranks this pathogen as the most frequently reported bacterial sexually transmitted infection across varied demographic groups [1]. Sustained diagnostic reporting reflects its continuous circulation within general populations, highlighting its enduring prevalence [1].
Primary dissemination occurs through direct sexual contact involving genital, anal, or oral mucosal exchange [1]. Ocular strain propagation is closely tied to environmental conditions and hygiene access within densely populated or resource-limited settlements [2]. Variations in healthcare delivery models and institutional competencies further shape how transmission networks are identified and interrupted [4].
Public health frameworks emphasize clinical management protocols and targeted screening initiatives to curb community spread [1]. Eradication campaigns for ocular disease utilize a multifaceted approach combining surgical correction, population-wide antimicrobial therapy, facial hygiene promotion, and infrastructure upgrades [2]. Operational challenges regarding diagnostic assay availability and laboratory service distribution require coordinated mitigation to sustain preventive efforts [4].
- 1Hocking JS et al. Update on the Epidemiology, Screening, and Management of Chlamydia trachomatis Infection. Infect Dis Clin North Am. 2023 Jun. PMID: 37005162. doi: 10.1016/j.idc.2023.02.007.PubMed: https://pubmed.ncbi.nlm.nih.gov/37005162/
- 2Habtamu E et al. Trachoma. Lancet. 2025 May 24. PMID: 40412861. doi: 10.1016/S0140-6736(25)00551-3.PubMed: https://pubmed.ncbi.nlm.nih.gov/40412861/
- 3Di Pietro M et al. Cervicovaginal Microbiota Composition in Chlamydia trachomatis Infection: A Systematic Review and Meta-Analysis. Int J Mol Sci. 2022 Aug 23. PMID: 36076948. doi: 10.3390/ijms23179554.PubMed: https://pubmed.ncbi.nlm.nih.gov/36076948/
- 4Del Romero J et al. Sexually transmitted infections in Spain: Current status. Rev Esp Quimioter. 2023 Oct. PMID: 37335757. doi: 10.37201/req/038.2023.PubMed: https://pubmed.ncbi.nlm.nih.gov/37335757/
- 5Passos LG et al. The Correlation between Chlamydia Trachomatis and Female Infertility: A Systematic Review. Rev Bras Ginecol Obstet. 2022 Jun. PMID: 35576969. doi: 10.1055/s-0042-1748023.PubMed: https://pubmed.ncbi.nlm.nih.gov/35576969/
Coverage
Reporting countries and regions
AustraliaAU
AustriaAT
BelgiumBE
BulgariaBG
CanadaCA
CroatiaHR
CyprusCY
DenmarkDK
EstoniaEE
FinlandFI
FranceFR
GreeceGR
HungaryHU
IcelandIS
IrelandIE
ItalyIT
LatviaLV
LiechtensteinLI
LithuaniaLT
LuxembourgLU
MaltaMT
NetherlandsNL
NorwayNO
PolandPL
PortugalPT
RomaniaRO
SlovakiaSK
SloveniaSI
SpainES
SwedenSE
SwitzerlandCH
United KingdomGB
United StatesUS
Trends by reporting country
Monthly patterns over time
Research Radar
Recent related research
Differences between males and females in infectious diseases notifications in the EU/EEA, 2012 to 2021
Eurosurveillance
Literature links are provided for discovery and do not alter or validate the surveillance series above.
Data access
Page dataset index with source links and update metadata.
Official sourcesAuthority, cadence, notes47
Austria AGES Radar for Infectious Diseases
Austria
AGES Radar monthly national source. Internal ingestion retains native categories; public release is disabled pending licence review.
Australia NINDSS
Australia
Australian national notifiable diseases surveillance dashboard.
Australia NINDSS — Australian Capital Territory
Australian Capital Territory, Australia
Australian NINDSS monthly state/territory notifications for Australian Capital Territory, kept separate from the Australia national aggregate.
Australia NINDSS — New South Wales
New South Wales, Australia
Australian NINDSS monthly state/territory notifications for New South Wales, kept separate from the Australia national aggregate.
Australia NINDSS — Northern Territory
Northern Territory, Australia
Australian NINDSS monthly state/territory notifications for Northern Territory, kept separate from the Australia national aggregate.
Australia NINDSS — Queensland
Queensland, Australia
Australian NINDSS monthly state/territory notifications for Queensland, kept separate from the Australia national aggregate.
Australia NINDSS — South Australia
South Australia, Australia
Australian NINDSS monthly state/territory notifications for South Australia, kept separate from the Australia national aggregate.
Australia NINDSS — Tasmania
Tasmania, Australia
Australian NINDSS monthly state/territory notifications for Tasmania, kept separate from the Australia national aggregate.
Australia NINDSS — Victoria
Victoria, Australia
Australian NINDSS monthly state/territory notifications for Victoria, kept separate from the Australia national aggregate.
Australia NINDSS — Western Australia
Western Australia, Australia
Australian NINDSS monthly state/territory notifications for Western Australia, kept separate from the Australia national aggregate.
ECDC Surveillance Atlas — Belgium Annual Baseline
Belgium
Belgium annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Bulgaria Annual Baseline
Bulgaria
Bulgaria annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Canada PHAC CNDSS Annual
Canada
Canada is the national jurisdiction; subdivision feeds are registered separately.
Public Health Ontario IDTO Monthly
Ontario, Canada
Ontario-level current-year preliminary monthly case counts from Public Health Ontario's IDTO report.
Switzerland FOPH IDD
Switzerland
Switzerland FOPH/BAG IDD mandatory reporting API normalized to national case rows. Monthly series may use the dashboard CHFL aggregate where CH-only monthly series are not exposed.
ECDC Surveillance Atlas — Cyprus Annual Baseline
Cyprus
Cyprus annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Denmark Annual Baseline
Denmark
Denmark annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Estonia Annual Baseline
Estonia
Estonia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Spain Annual Baseline
Spain
Spain annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Finland THL Infectious Diseases Register
Finland
Finland THL Infectious Diseases Register national monthly case counts. The current month is ingested as provisional and the latest three months are refreshed for source revisions.
ECDC Surveillance Atlas — France Annual Baseline
France
France annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — United Kingdom Annual Baseline
United Kingdom
United Kingdom annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Greece Annual Baseline
Greece
Greece annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Croatia Annual Baseline
Croatia
Croatia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Hungary Annual Baseline
Hungary
Hungary annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Ireland HPSC Notifiable Diseases Hub
Ireland
Ireland HPSC national weekly notifiable-disease totals from the official ArcGIS FeatureServer. Internal ingestion is enabled; public release remains disabled pending written redistribution permission.
Iceland Directorate of Health Annual Dashboard
Iceland
National annual case notifications by disease. Published values can be revised retrospectively and remain annual period totals.
Iceland Directorate of Health STI Dashboard
Iceland
Monthly STI diagnosis facts from laboratory and registry surveillance; the official dashboard is published on a quarterly schedule.
Iceland Directorate of Health Respiratory Dashboard
Iceland
ISO-week respiratory diagnosis counts. Hospitalizations, samples, and vaccination indicators are separate measures and are not counted as diagnoses.
Iceland Directorate of Health Historical Registry
Iceland
Historical official registry tables for 1997–2021, with annual totals and disease-specific monthly notification facts retained at source grain.
Iceland Directorate of Health Legacy ICD Monthly
Iceland
Historical Saga EHR ICD encounter counts for 1997–2020. This clinical measure is non-comparable with registry notifications and is kept separate.
ECDC Surveillance Atlas — Italy Annual Baseline
Italy
Italy annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Liechtenstein Annual Baseline
Liechtenstein
Liechtenstein annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Lithuania Annual Baseline
Lithuania
Lithuania annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Luxembourg Annual Baseline
Luxembourg
Luxembourg annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Latvia Annual Baseline
Latvia
Latvia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Malta Annual Baseline
Malta
Malta annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Netherlands Annual Baseline
Netherlands
Netherlands annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Norway FHI MSIS Statistics Bank
Norway
Norway FHI MSIS national monthly notifications from the official Allvis frontend API; adapter contract checks guard the unversioned endpoint.
ECDC Surveillance Atlas — Poland Annual Baseline
Poland
Poland annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Portugal Annual Baseline
Portugal
Portugal annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Romania Annual Baseline
Romania
Romania annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
Sweden Public Health Agency SmiNet
Sweden
Sweden SmiNet national monthly reported cases from the official Public Health Agency statistics pages; public release is enabled with closed-month publication and revisable recent-month refreshes.
ECDC Surveillance Atlas — Slovenia Annual Baseline
Slovenia
Slovenia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
ECDC Surveillance Atlas — Slovakia Annual Baseline
Slovakia
Slovakia annual Member-State reported case counts from the ECDC Surveillance Atlas. Missing topic/year cells remain unknown and published zeroes are preserved. Data provided by ECDC based on data reported by EU/EEA Member States.
US CDC NNDSS
United States
CDC National Notifiable Diseases Surveillance System provisional data.
US CDC NHSS HIV
United States
CDC NNDSS weekly data plus NHSS annual national HIV diagnoses