Conditions · Ophthalmology and ENT
Trachoma !
A chlamydial eye infection spread in poor, crowded places; repeated bouts scar the eyelid until the lashes scratch the cornea and cause blindness.
Updated 2026-11-01
Structures involved
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Microorganisms that cause it
Why it happens
- Chronic inflammation: causes, cells and features
- Fibrosis in organs: TGF-β and the myofibroblast
- Conjunctiva, eyelid glands and lacrimal gland
What it is
A chronic keratoconjunctivitis caused by repeated infection with Chlamydia trachomatis (ocular serovars A to C). It is the leading infectious cause of blindness in the world and a neglected tropical disease targeted for elimination.
Who gets it
Concentrated in poor rural communities with little water and sanitation. In the Americas it is still endemic in remote areas of Brazil, Colombia, Guatemala and Peru; in Colombia the known focus is among Indigenous communities of the Amazon (Vaupés and neighbouring departments). Mexico was the first country in the region to eliminate it as a public health problem.
Causes
- Chlamydia trachomatis serovars A, B, Ba and C
- Spread by eye and nose discharge on hands, cloths and bedding
- Eye-seeking flies that land on dirty faces
- Young children are the main reservoir; transmission happens within families
Risk factors
- Poor access to water and sanitation
- Crowded households
- Dirty faces in children
- Flies breeding in open faeces
- Women, who look after children and get more re-infections, are more often blinded
Pathophysiology
Repeated chlamydial infections of the upper tarsal conjunctiva cause follicles and intense inflammation in childhood. Over years, healing produces scars that shorten the inner lid, turning it inward (entropion) so the lashes rub the cornea (trichiasis). Constant abrasion leads to corneal ulcers and opacity, usually in adults aged 30 to 40.
Classification
- WHO simplified grading: TF, follicular inflammation
- TI, intense inflammation
- TS, conjunctival scarring
- TT, trichiasis
- CO, corneal opacity
Symptoms and signs
- Red, irritated eyes with discharge in children
- Follicles on the inner upper eyelid
- Gritty feeling, light sensitivity and tearing
- In adults: lashes turning in and rubbing the eye, with pain
- Gradual loss of vision from corneal clouding
Diagnosis
- Clinical
- Clinical, by everting the upper eyelid and grading with the WHO simplified system, usually in community surveys; the prevalence of TF in children aged 1 to 9 guides mass treatment.
- Tests
- Nucleic acid amplification tests for C. trachomatis in surveillance and research; not needed for individual care.
- Imaging
- Not used.
Differential diagnosis
- Viral or allergic follicular conjunctivitis
- Adult inclusion conjunctivitis (genital serovars D to K)
- Neonatal conjunctivitis
- Other causes of entropion and trichiasis
Goal of treatment
Clear infection in the community to stop transmission, correct trichiasis to prevent blindness, and change the hygiene and environmental conditions that keep trachoma going (the WHO SAFE strategy).
Treatment
- Surgical
- S, surgery: eyelid surgery (tarsal rotation) for trachomatous trichiasis; epilation of lashes as a temporary measure.
- Medical
- A, antibiotics: mass administration of oral azithromycin to whole communities where active trachoma is common; topical tetracycline is an alternative in some groups.
- Lifestyle
- F, facial cleanliness: daily face washing of children to reduce spread.
- Lifestyle
- E, environmental improvement: safe water, latrines and fly control.
- Follow-up
- Community surveys of active trachoma and trichiasis to decide when mass treatment can stop and to confirm elimination.
Complications
- Entropion and trichiasis
- Corneal ulcer and scarring
- Irreversible visual impairment and blindness
- Dry eye and secondary bacterial infection
- Loss of work and independence
Prognosis
Active disease responds well to antibiotics, but re-infection is common without hygiene and water improvements. Once corneal opacity develops, vision loss is permanent; timely lid surgery prevents further damage.
Prevention
- Face washing and hand hygiene
- Access to clean water and latrines
- Mass azithromycin in endemic communities
Test yourself
Think of the answer, then tap the question to see it.
Which organism and serovars cause trachoma?
Chlamydia trachomatis, ocular serovars A to C.
What does the acronym SAFE stand for in trachoma control?
Surgery for trichiasis, Antibiotics (mass azithromycin), Facial cleanliness and Environmental improvement.
How does trachoma cause blindness?
Repeated infections scar the upper lid, which turns inward so lashes scratch the cornea, causing ulcers and opacity.
Where is trachoma endemic in Colombia?
In remote Indigenous communities of the Amazon, especially Vaupés.
Related conditions
- Conjunctivitis
- Chlamydia infection
- Keratitis and corneal ulcer
- Corneal abrasion and ocular foreign body
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Trachoma (World Health Organization, 2025); Trachoma - PAHO/WHO | Pan American Health Organization (Pan American Health Organization, 2026).
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