Trachoma

Synonyms

3

Overview

Trachoma (also called granular conjunctivitis, Egyptian ophthalmia, and blinding trachoma), is an infectious disease caused by the bacterium Chlamydia trachomatis. The infection causes a roughening of the inner surface of the eyelids. This roughening can lead to pain in the eyes, breakdown of the outer surface or cornea of the eyes, and possibly blindness. Untreated, repeated trachoma infections can result in a form of permanent blindness when the eyelids turn inward.

The bacteria that cause the disease can be spread by both direct and indirect contact with an affected person's eyes or nose. Indirect contact includes through clothing or flies that have come into contact with an affected person's eyes or nose. Children spread the disease more often than adults. Poor sanitation, crowded living conditions, and not enough clean water and toilets also increase spread.

Efforts to prevent the disease include improving access to clean water and decreasing the number of people infected by treatment with antibiotics. This may include treating, all at once, whole groups of people in whom the disease is known to be common. Washing by itself is not enough to prevent disease but may be useful with other measures. Treatment options include oral azithromycin and topical tetracycline. Azithromycin is preferred because it can be used as a single oral dose. After scarring of the eyelid has occurred, surgery may be required to correct the position of the eyelashes and prevent blindness.

Globally, about 80 million people have an active infection. In some areas infections may be present in as many as 60–90% of children and it more commonly affects women than men likely due to their closer contact with children. The disease is the cause of a poor ability to see in 2.2 million people of which 1.2 million are completely blind. It commonly occurs in 53 countries of Africa, Asia, Central and South America with about 230 million people at risk. It results in 8 billion USD of economic losses a year. It belongs to a group of diseases known as neglected tropical diseases.

Symptoms

The bacterium has an incubation period of 5 to 12 days, after which the affected individual experiences symptoms of conjunctivitis, or irritation similar to "pink eye." Blinding endemic trachoma results from multiple episodes of reinfection that maintains the intense inflammation in the conjunctiva. Without reinfection, the inflammation will gradually subside.

The conjunctival inflammation is called “active trachoma” and usually is seen in children, especially pre-school children. It is characterized by white lumps in the undersurface of the upper eyelid (conjunctival follicles or lymphoid germinal centres) and by non-specific inflammation and thickening often associated with papillae. Follicles may also appear at the junction of the cornea and the sclera (limbal follicles). Active trachoma will often be irritating and have a watery discharge. Bacterial secondary infection may occur and cause a purulent discharge.

The later structural changes of trachoma are referred to as “cicatricial trachoma”. These include scarring in the eyelid (tarsal conjunctiva) that leads to distortion of the eyelid with buckling of the lid (tarsus) so the lashes rub on the eye (trichiasis). These lashes will lead to corneal opacities and scarring and then to blindness. Linear scar present in the Sulcus subtarsalis is called Arlt's line (named after Carl Ferdinand von Arlt). In addition, blood vessels and scar tissue can invade the upper cornea (pannus). Resolved limbal follicles may leave small gaps in pannus (Herbert’s Pits).

Most commonly children with active trachoma will not present with any symptoms as the low grade irritation and ocular discharge is just accepted as normal. However, further symptoms may include:

  • Eye discharge
  • Swollen eyelids
  • Trichiasis (turned-in eyelashes)
  • Swelling of lymph nodes in front of the ears
  • Sensitivity to bright lights
  • Increased heart rate
  • Further ear, nose and throat complications.

The major complication or the most important one is corneal ulcer occurring due to rubbing by concentrations, or trichiasis with superimposed bacterial infection.

Causes

Trachoma is caused by Chlamydia trachomatis, serotypes (serovars) A, B, and C. It is spread by direct contact with eye, nose, and throat secretions from affected individuals, or contact with fomites (inanimate objects that carry infectious agents), such as towels and/or washcloths, that have had similar contact with these secretions. Flies can also be a route of mechanical transmission. Untreated, repeated trachoma infections result in entropion—a painful form of permanent blindness when the eyelids turn inward, causing the eyelashes to scratch the cornea. Children are the most susceptible to infection due to their tendency to easily get dirty, but the blinding effects or more severe symptoms are often not felt until adulthood.

Blinding endemic trachoma occurs in areas with poor personal and family hygiene. Many factors are indirectly linked to the presence of trachoma including lack of water, absence of latrines or toilets, poverty in general, flies, close proximity to cattle, crowding, and so forth. However, the final common pathway seems to be the presence of dirty faces in children that facilitates the frequent exchange of infected ocular discharge from one child's face to another. Most transmission of trachoma occurs within the family.

Prevention

Although trachoma was eliminated from much of the developed world in the 20th century, this disease persists in many parts of the developing world, particularly in communities without adequate access to water and sanitation.

Environmental measures

Environmental improvement: Modifications in water use, fly control, latrine use, health education, and proximity to domesticated animals have all been proposed to reduce transmission of C. trachomatis. These changes pose numerous challenges for implementation. It seems likely that these environmental changes ultimately impact on the transmission of ocular infection by means of lack of facial cleanliness. Particular attention is required for environmental factors that limit clean faces.

A systematic review examining the effectiveness of environmental sanitary measures on the prevalence of active trachoma in endemic areas showed that usage of insecticide spray resulted in significant reductions of trachoma and fly density in some studies. Health education also resulted in reductions of active trachoma when implemented. Improved water supply did not result in a reduction of trachoma incidence.

Antibiotics

Antibiotic therapy: WHO Guidelines recommend that a region should receive community-based, mass antibiotic treatment when the prevalence of active trachoma among one- to nine-year-old children is greater than 10 percent. Subsequent annual treatment should be administered for three years, at which time the prevalence should be reassessed. Annual treatment should continue until the prevalence drops below five percent. At lower prevalences, antibiotic treatment should be family-based.

Diagnosis

McCallan's classification

McCallan in 1908 divided the clinical course of trachoma into 4 stages:

Stage 1 (Incipient trachoma)

  • Hyperaemia of palpebral conjunctiva
  • Immature follicle

Stage 2 (Established trachoma)

  • Appearance of mature follicle & papillae
  • Progressive corneal pannus

Stage 3 (Cicatrising trachoma)

  • Scarring of palpebral conjunctiva
  • Scars are easily visible as white bands

Stage 4 (Healed trachoma)

  • Disease is cured or is not markable
  • Sequelae to cicatrisation cause symptoms

WHO classification

The World Health Organization recommends a simplified grading system for trachoma. The Simplified WHO Grading System is summarized below:

  • Trachomatous inflammation, follicular (TF)—Five or more follicles of >0.5 mm on the upper tarsal conjunctiva
  • Trachomatous inflammation, intense (TI)—Papillary hypertrophy and inflammatory thickening of the upper tarsal conjunctiva obscuring more than half the deep tarsal vessels
  • Trachomatous scarring (TS)—Presence of scarring in tarsal conjunctiva.
  • Trachomatous trichiasis (TT)—At least one ingrown eyelash touching the globe, or evidence of epilation (eyelash removal)
  • Corneal opacity (CO)—Corneal opacity blurring part of the pupil margin


Prognosis

If not treated properly with oral antibiotics, the symptoms may escalate and cause blindness, which is the result of ulceration and consequent scarring of the cornea. Surgery may also be necessary to fix eyelid deformities.

Without intervention, trachoma keeps families shackled within a cycle of poverty, as the disease and its long-term effects are passed from one generation to the next.

Treatment

Antibiotics

Antibiotic selection: Azithromycin (single oral dose of 20 mg/kg) or topical tetracycline (one percent eye ointment twice a day for six weeks). Azithromycin is preferred because it is used as a single oral dose. Although it is expensive, it is generally used as part of the international donation program organized by Pfizer through the International Trachoma Initiative. Azithromycin can be used in children from the age of six months and in pregnancy. As a community-based antibiotic treatment, some evidence suggests that oral azithromycin was more effective than topical tetracycline; however, there was no consistent evidence that supported oral or topical antibiotics as being more effective. Antibiotic treatment reduces the risk of active trachoma in individuals infected with chlamydia trachomatis.

Surgery

Surgery: For individuals with trichiasis, a bilamellar tarsal rotation procedure is warranted to direct the lashes away from the globe. Evidence suggests that usage of a lid clamp and absorbable sutures would result in reduced lid contour abnormalities and granuloma formulation post-surgery. Early intervention is beneficial as the rate of recurrence is higher in more advanced disease.

Lifestyle measures

Facial cleanliness: Children with grossly visible nasal discharge, ocular discharge, or flies on their faces are at least twice as likely to have active trachoma as children with clean faces. Intensive community-based health education programs to promote face-washing can significantly reduce the prevalence of active trachoma, especially intense trachoma (TI). If somebody is already infected washing one’s face is strongly encouraged, especially a child, in order to prevent re-infection. Some evidence exists that washing the face combined with topical tetracycline might be more effective in reducing severe trachoma compared to topical tetracycline alone. The same trial found no statistically significant benefit of eye washing alone or in combination with tetracycline eye drops in reducing follicular trachoma amongst children.

National governments in collaboration with numerous non-profit organizations implement trachoma control programs using the WHO-recommended SAFE strategy, which includes:

  • Surgery to correct advanced stages of the disease;
  • Antibiotics to treat active infection, using azithromycin
  • Facial cleanliness to reduce disease transmission;
  • Environmental change to increase access to clean water and improved sanitation.