Trachoma

Trachoma is an infectious disease caused by bacterium Chlamydia trachomatis.

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Entropion and trichiasis secondary to trachoma

The bacteria that cause the disease can be spread by both direct and indirect contact with an affected person's eyes or nose.

Trachoma is a bacterial eye infection caused by the bacterium Chlamydia trachomatis. It is spread through contact with infected eye and nose secretions, often through direct personal contact, shared towels or cloths, as well as eye-seeking flies.

Repeated infection can develop into a condition known as trichiasis, in which scarring and inward turning of the eyelid causes the eyelashes to scrape against the cornea of the eye. If left untreated, this painful condition can result in permanent blindness.

According to the World Health Organization (WHO), more than 190 million people in 41 countries are at risk for trachoma. Trachoma is responsible for the visual impairment of an estimated 1.9 million people worldwide, half a million of whom are irreversibly blind. Trachoma is commonly found in areas with limited access to adequate water, sanitation and basic hygiene.

• Trachoma can result in loss of vision, blindness, loss of social status and stigmatization and can place a tremendous economic burden on individuals, families and communities.
• Research suggests children have higher rates of trachoma infection than other age groups. In endemic areas, prevalence rates can be as high as 60 percent to 90 percent among school-aged children.
• Women are blinded two to three times more often than men, likely due to their close contact with infected children and their resulting greater frequency of infection episodes.
• An estimated 7.3 million require surgery for trachomatous trichiasis.
• Blindness from unoperated trachomatous trichiasis strikes adults in their prime years (30–40 years of age), hindering their ability to care for themselves and their families.

Chlamydia trachomatis

The disease’s long-term effects can have an impact on multiple generations of families. Globally, trachoma causes between an estimated US$ 3—6 billion loss in productivity per year.

The World Health Organization has targeted trachoma for elimination by 2020 through an innovative, multi-faceted public health strategy known as S.A.F.E.:

• Surgery to correct the advanced, blinding stage of the disease (trichiasis),
• Antibiotics to treat active infection,
• Facial cleanliness and,
• Environmental improvements in the areas of water and sanitation to reduce disease transmission

The comprehensive SAFE strategy combines measures for the treatment of active infection and trichiasis (S&A) with preventive measures to reduce disease transmission (F&E). Implementation of the full SAFE strategy in endemic areas increases the effectiveness of trachoma programs. The F and E components of SAFE, which reduce disease transmission, are particularly critical to achieving sustainable elimination of trachoma.

• The “F” in the SAFE strategy refers to facial cleanliness. Because trachoma is transmitted through close personal contact, it tends to occur in clusters, often infecting entire families and communities. Children, who are more likely to touch their eyes and have unclean faces that attract eye-seeking flies, are especially vulnerable to infection, as are women 8, the traditional caretakers of the home. Therefore, the promotion of good hygiene practices, such as hand washing and the washing of children’s faces at least once a day with water, is a key step in breaking the cycle of trachoma transmission.

• The “E” in the SAFE strategy refers to environmental change. Improvements in community and household sanitation, such as the provision of household latrines, help control fly populations and breeding grounds. Increased access to water facilitates good hygiene practices and is vital to achieving sustainable elimination of the disease 10. Separation of animal quarters from human living space, as well as safe handling of food and drinking water, are also important environmental measures that affected communities can take within a trachoma control program.

Efforts to prevent the disease include improving access to clean water and treatment with antibiotics to decrease the number of people infected with the bacterium. This may include treating, all at once, whole groups of people in whom the disease is known to be common.<

Diagnosis

McCallan's classification

McCallan in 1908 divided the clinical course of trachoma into four stages.

Stage 1 (Incipient trachoma)	Stage 2 (Established trachoma)	Stage 3 (Cicatrising trachoma)	Stage 4 (Healed trachoma)
Hyperaemia of palpebral conjunctiva	Appearance of mature follicle & papillae	Scarring of palpebral conjunctiva	Disease is cured or is not markable
Immature follicle	Progressive corneal pannus	Scars are easily visible as white bands	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:

Chlamydia trachomatis

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

Prevention

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

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.
• 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.
• 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.

Chlamydia trachomatis male

Surgery

Surgery: For individuals with trichiasis, a bilamellar tarsal rotation procedure is warranted to direct the lashes away from the globe.

Lifestyle measures

Pap smear showing chlamydia in the vacuoles

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

Children with visible nasal discharge, discharge from the eyes, or flies on their faces are at least twice as likely to have active trachoma as children with clean faces.

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.

References

• CDC Disease Info trachoma

• Celia W. Dugger (31 March 2006), "Preventable Disease Blinds Poor in Third World", The New York Times
• Photographs of trachoma patients
• Trachoma Atlas
• International Trachoma Initiative