Trachoma
Trachoma is an infectious disease caused by 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 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 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 38 countries across Africa, Asia, the Middle East, Central and South America, and Australia. 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 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 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 and by nonspecific inflammation and thickening, often associated with papillae. Follicles may also appear at the junction of the cornea and the sclera. 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 that leads to distortion of the eyelid with buckling of the lid so the lashes rub against the eye. This can lead to corneal opacities and scarring and then to blindness. Linear scars present in the sulcus subtarsalis are called Arlt's lines. In addition, blood vessels and scar tissue can invade the upper cornea. Resolved limbal follicles may leave small gaps in the pannus.
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
- Swelling of lymph nodes in front of the ears
- Sensitivity to bright lights
- Increased heart rate
- Further ear, nose, and throat complications.
Cause
Trachoma is caused by Chlamydia trachomatis, serotypes A, B, and C. It is spread by direct contact with eye, nose, and throat secretions from affected individuals, or contact with fomites, 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, which may result in blindness due to damage to the cornea. Children are the 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 in general, flies, close 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 | Stage 2 | Stage 3 | Stage 4 |
| 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:Trachomatous inflammation, follicular —Five or more follicles of >0.5 mm on the upper tarsal conjunctiva
Trachomatous inflammation, intense —Papillary hypertrophy and inflammatory thickening of the upper tarsal conjunctiva obscuring more than half the deep tarsal vessels
Trachomatous scarring —Presence of scarring in tarsal conjunctiva.
Trachomatous trichiasis —At least one ingrown eyelash touching the globe, or evidence of epilation
Corneal opacity —Corneal opacity blurring part of the pupil margin
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. 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 ultimately 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 should 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
or topical tetracycline. 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. 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