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 eye pain, breakdown of the outer surface or cornea of the eyes, and eventual 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 insufficient clean water and toilets also increase the spread.
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. 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. Among adults it more commonly affects women than men, likely due to their closer contact with children. The disease is the cause of decreased vision in 2.2 million people, of whom 1.2 million are completely blind. Trachoma is a public health problem in 37 countries across Africa, Asia, the Middle East, and Central and South America. There are 103 million people at risk, down from 228.9 million in 2013. It results in US$8 billion of economic losses a year. It belongs to a group of diseases known as neglected tropical diseases.
Signs and symptoms
The bacterium has an incubation period of 10 days, after which the affected individual experiences symptoms of conjunctivitis or "pink eye". Blinding endemic trachoma results from multiple episodes of reinfection that maintains the intense inflammation in the conjunctiva. Without reinfection, the inflammation gradually subsides.
The conjunctival inflammation is called "active trachoma" and is usually seen in children, especially those in preschool. It is characterized by white lumps in the undersurface of the upper eyelid (conjunctival follicles or lymphoid germinal centers) and by nonspecific inflammation and thickening, often associated with papillae. Follicles may also appear at the junction of the cornea and the sclera (limbal follicles). Active trachoma can often be irritating and have a watery discharge. Bacterial secondary infection may occur and cause a discharge of pus.
The later structural changes of trachoma are referred to as "cicatricial trachoma". These include scarring under the eyelid (tarsal conjunctiva) that distorts the eyelid with buckling of the lid (tarsus), so the lashes rub against the eye (trichiasis). This can lead to corneal opacities and scarring and then to blindness. Linear scars present in the sulcus subtarsalis are called Arlt's lines (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 the pannus (Herbert's pits).
Most commonly, children with active trachoma do not present with symptoms, as the low-grade irritation and ocular discharge are just accepted as normal, but further symptoms may include: Eye discharge Swollen eyelids Trichiasis (misaligned eyelashes) Swelling of lymph nodes in front of the ears Sensitivity to bright lights Increased heart rate Further ear, nose, and throat complications. The most important complication to look out for is a corneal ulcer, which is caused by intense rubbing of the affected eye, or trichiasis with a superimposed bacterial infection.
Cause 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 (the inward turning of the eyelids), which may result in blindness due to damage to the cornea. Children are most susceptible to infection due to their tendency to get dirty easily, 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, flies, proximity to cattle, and crowding. The final common pathway, though, seems to be the presence of dirty faces in children, facilitating the frequent exchange of infected ocular discharge from one child's face to another. Most transmission of trachoma occurs within the family.
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 the palpebral conjunctiva Appearance of mature follicle & papillae Scarring of the 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:
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 the 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 the developed world in the 20th and 21st centuries, this disease persists in many parts of the developing world, particularly in communities without adequate access to water and sanitation. It is grouped as a neglected tropical disease which is a target for preventive chemotherapy.
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. These environmental changes are likely to affect the transmission of ocular infection through a 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 the use 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 WHO Guidelines recommend that a region receive community-based, mass antibiotic treatment when the prevalence of active trachoma among one- to nine-year-old children is greater than 10%. 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 5%. At lower prevalences, antibiotic treatment should be family-based.
Management
Antibiotics Azithromycin (single oral dose of 20 mg/kg) or topical tetracycline (1% 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. 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, but no consistent evidence supported either oral or topical antibiotics as being more effective. Antibiotic treatment reduces the risk of active trachoma in individuals infected with chlamydial trachomatis.
Surgery For individuals with trichiasis, a bilamellar tarsal rotation procedure is warranted to direct the lashes away from the globe.Reacher M, Foster A, Huber J. "Trichiasis Surgery for Trachoma. The Bilamellar Tarsal Rotation Procedure." 1993; World Health Organization, Geneva: WHO/PBL/93.29. Evidence suggests that the use of a lid clamp and absorbable sutures would result in reduced lid contour abnormalities and granuloma formulation after surgery. Early intervention is beneficial as the rate of recurrence is higher in more advanced diseases.
Lifestyle measures
The WHO-recommended SAFE strategy 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 improve sanitation
Children with visible nasal discharge, eye 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 reduce the rates of active trachoma, especially intense trachoma. If an individual is already infected, washing one's face is encouraged, especially for a child, to prevent reinfection.Prevention-Trachoma 18 July 2008 – 24 March 2009 Some evidence shows 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 statistical benefit of eye washing alone or in combination with tetracycline eye drops in reducing follicular trachoma amongst children.
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 in a cycle of poverty, as the disease and its long-term effects are passed from one generation to the next.
Epidemiology
As of 2011, about 21 million people were actively affected by trachoma, with around 2.2 million people being permanently blind or having severe visual impairment from trachoma. An additional 7.3 million people are reported to have trichiasis. 103 million individuals live in trachoma endemic areas and are at risk of trachoma-related blindness, and the disease is a public health problem in 37 countries. Of these, Africa is considered the worst affected area, with over 85% of all known active cases of trachoma. Within the continent, South Sudan and Ethiopia have the highest prevalence. In many of these communities, women are up to four times more likely than men to be blinded by the disease, likely due to their roles as caregivers in the family.
Elimination