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trachoma

[truh-koh-muh]

trachoma, infection of the mucous membrane of the eyelids caused by the bacterium Chlamydia trachomatis. Trachoma infects more than 150 million people worldwide. An estimated 6 million people have become blind because of it, making the disease the second leading cause of blindness, after cataracts. It is most common in parts of Africa, the Middle East, and Asia. In the United States it has occurred sporadically among Native Americans and in mountainous areas of the South.

Trachoma is highly contagious in its early stages and is transmitted by direct contact with infected persons or articles (e.g., towels, handkerchiefs) and possibly also by flies. It begins as congestion and swelling of the eyelids with tearing and disturbance of vision. The cornea is often involved. If left untreated, scar tissue forms, which causes deformities of the eyelids and, if there is corneal involvement, partial or total blindness. The disease has been effectively treated with tetracycline ointment and with the newer oral drug azithromycin (Zithromax). The World Health Organization began a campaign in 1998 to eradicate the disease worldwide by the year 2020. The strategy includes use of azithromycin and sanitation improvements in water supplies.

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Trachoma

Trachoma (Ancient Greek: "rough eye") is an infectious eye disease, and the leading cause of the world's infectious blindness. Globally, 84 million people suffer from active infection and nearly 8 million people are visually impaired as a result of this disease. Globally this disease results in an estimated US $2.9 billion in lost productivity every year.

Causes

Trachoma is caused by the bacterium Chlamydia trachomatis and it is spread by direct contact with eye, nose, and throat secretions from affected individuals, or contact with fomites (inanimate objects), such as towels and/or washcloths, that have had similar contact with these secretions. 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, but the blinding effects 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 last century, this disease persists in many parts of the developing world particularly in communities without adequate access to water and sanitation. In many of these communities, women are three times more likely than men to be blinded by the disease.

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.

The World Health Organization (WHO) has set a goal of eliminating blinding trachoma as a public health concern by 2020. 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 Zithromax (azithromycin) donated by Pfizer Inc through the International Trachoma Initiative;
Facial cleanliness to reduce disease transmission;
Environmental change to increase access to clean water and improved sanitation.

Surgery: For individuals with trichiasis, a bilamellar tarsal rotation procedure is warranted to direct the lashes away from the globe. Early intervention is beneficial as the rate of recurrence is higher in more advanced disease.

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.

Antibiotic selection: WHO recommends azithromycin (single oral dose of 20mg/kg) or topical tetracycline (one percent eye ointment twice a day for six weeks). Azithrtomycin 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. 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).

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.

Symptoms

The bacteria 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 eye lid (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 eye lid (tarsal conjunctiva) that leads to distortion of the eye lid 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. 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).

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 >0.5mm 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 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

Further symptoms include:

Eye discharge
Swollen eyelids
Trichiasis (turned-in eyelashes)
Swelling of lymph nodes in front of the ears
Corneal scarring
Further ear, nose and throat complications.

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.

History

The disease is one of the earliest recorded eye afflictions, having been identified in Egypt as early as 15 B.C.

Its presence was also recorded in ancient China and Mesopotamia. Trachoma became a problem as people moved in crowded settlements or towns where hygiene was poor. It became a particular problem in Europe in the 19th Century. After the Egyptian Campaign (1798 – 1802) and the Napoleonic Wars (1798 – 1815), trachoma was rampant in the army barracks of Europe and spread to those living in towns as troops returned home. Stringent control measures were introduced and by the early 20th Century, trachoma was essentially controlled in Europe, although cases were reported up until the 1950s. Today, most victims of trachoma live in underdeveloped and poverty-stricken countries in Africa, the Middle East, and Asia.

Rare in the United States, the disease can be treated with antibiotics and prevented with adequate hygiene and education. According to the Centers for Disease Control, "No national or international surveillance [for trachoma] exists. Blindness due to trachoma has been eliminated from the United States. The last cases were found among American Indian populations and in Appalachia.

In 1913, President Woodrow Wilson signed an act designating funds for the eradication of the disease. The people that went through Ellis Island had to be checked for trachoma. By the late 1930s, a number of ophthalmologists reported success in treating trachoma with sulfonamide antibiotics. In 1948, Vincent Tabone (who was later to become the President of Malta) was entrusted with the supervision of a campaign in Malta to treat trachoma using sulfonamide tablets and drops.

Although by the 1950s, trachoma had virtually disappeared from the industrialized world, thanks to improved sanitation and overall living conditions, it continues to plague the developing world. This potentially blinding disease remains endemic in the poorest regions of Africa, Asia, and the Middle East and in some parts of Latin America and Australia. Currently, 8 million people are visually impaired as a result of trachoma, and 84 million suffer from active infection.