Trachoma

What trachoma is

Trachoma is caused by particular strains (serovars A, B, Ba and C) of Chlamydia trachomatis, the same species that causes the sexually transmitted infection chlamydia. The eye strains spread differently and cause a long-term scarring disease.

A single infection behaves like a mild conjunctivitis and clears. The problem is repeated infection over many years. Each episode inflames the conjunctiva lining the upper eyelid. Over time, the inflammation turns into scar tissue, which contracts and pulls the lid edge inward. The eyelashes then rub against the eyeball with every blink.

The World Health Organization estimates that trachoma is responsible for the visual impairment or blindness of around 2 million people, and that more than 100 million people live in areas where it is endemic. Women are affected by blinding trachoma up to several times more often than men, largely because they care for infected children.

How trachoma spreads

• Eye and nose discharge passed on fingers, shared towels, clothes and bedding
• Eye-seeking flies (especially Musca sorbens) that land on children's faces
• Crowded living conditions, shortages of water for washing, and open defecation, which provides breeding sites for flies

Young children in endemic communities are the main reservoir of infection.

Symptoms

Active infection

• red, irritated eyes
• itching and mild pain
• discharge of mucus or pus
• swollen eyelids
• light sensitivity

Many children have few symptoms despite active infection.

Late disease

• a constant feeling of grit or a foreign body in the eye
• eyelashes visibly turning in (trichiasis) and the eyelid edge rolling inward (entropion)
• severe pain with blinking
• cloudy or white areas on the cornea
• gradual, painful loss of vision

Stages of trachoma

Field workers and doctors use the WHO simplified grading system, examining the inside of the upper eyelid with a magnifying loupe:

How it is diagnosed

Trachoma is diagnosed clinically by flipping the upper eyelid and grading what is seen. Laboratory tests such as PCR for Chlamydia are used in surveys to monitor elimination programs, rather than for individual diagnosis. Outside endemic areas, a doctor will consider trachoma in someone with chronic follicular conjunctivitis and a history of living in an affected region.

Conditions that look similar

• Adult inclusion conjunctivitis: caused by the sexually transmitted strains of Chlamydia, usually in young adults, without progressive scarring
• Viral conjunctivitis and allergic conjunctivitis
• Trichiasis from other causes, such as burns or autoimmune scarring diseases

Treatment

Antibiotics

• Azithromycin as a single oral dose is the standard treatment for active trachoma, and is the drug used for mass distribution in endemic communities.
• Tetracycline eye ointment, applied for several weeks, is an alternative, including for young infants.

In endemic districts, whole communities are treated once a year for at least 3 years, because treating individuals alone allows rapid reinfection.

Surgery for trichiasis

Eyelid surgery rotates the lid margin outward so lashes no longer touch the eye. The most widely used procedures are the bilamellar tarsal rotation and posterior lamellar tarsal rotation. Surgery is quick, done under local anesthetic, and can be performed by trained non-physicians in community settings. It stops further corneal damage, although lost vision from scarring does not return. Inturned lashes can recur in a proportion of patients, so follow-up is needed.

Pulling out lashes (epilation) gives temporary relief when surgery is not immediately available.

Corneal damage

A corneal ulcer needs prompt antibiotic treatment. Severe corneal scarring may be helped by a corneal transplant, though results are poorer in trachoma than in other conditions and access is limited.

The SAFE strategy

The WHO and its partners aim to eliminate trachoma as a public health problem using SAFE:

• Surgery for trichiasis
• Antibiotics to clear infection
• Facial cleanliness, especially washing children's faces
• Environmental improvement: access to clean water and latrines

Many countries have been validated by WHO as having eliminated trachoma as a public health problem, including Morocco, Oman, Ghana, Nepal, Gambia, Malawi and others in recent years.

Prevention for travelers and families

Trachoma is very unlikely to affect short-term travelers. In endemic areas, washing faces and hands, not sharing towels, and controlling flies reduce risk. Newborns can catch the sexually transmitted strains of Chlamydia from the mother at birth, causing a different eye infection; this is prevented by prenatal screening and treatment.

Frequently asked questions

What causes trachoma?

Trachoma is caused by eye strains of the bacterium Chlamydia trachomatis. It spreads through contact with eye and nose discharge from infected people, via hands, towels and clothing, and through flies that feed on the eyes and faces of children. Poor access to water and sanitation drives transmission.

How does trachoma cause blindness?

Years of repeated infection scar the inner surface of the upper eyelid. The scars pull the eyelid edge inward so the eyelashes scrape the cornea with every blink. This damages and clouds the cornea, causing painful and permanent loss of vision.

Is trachoma contagious?

Yes. Active trachoma spreads easily between people, especially young children living closely together, through eye and nose secretions, shared cloths and flies. Late scarring stages are not contagious. Antibiotics quickly reduce infectiousness.

Can trachoma be cured?

Active infection is cured with a single dose of azithromycin or a course of tetracycline eye ointment. Eyelid scarring cannot be reversed, but surgery to turn the lashes outward prevents further damage to the eye. Vision already lost to corneal scarring usually does not return.

Is trachoma the same as chlamydia?

They are caused by the same species of bacteria, Chlamydia trachomatis, but by different strains. Trachoma strains infect the eyes and spread through close everyday contact and flies. The sexually transmitted strains cause genital chlamydia and, occasionally, eye infections in adults and newborns.