Trachoma is the leading infectious cause of blindness worldwide. In Western countries, few people know about the disease, but in the poorest countries in Africa, incidence among children can reach 40 percent.
A chronic bacterial infection of the eye, trachoma spreads through direct contact with the eye, nose or throat secretions of infected people. It's very contagious and almost always affects both eyes.
If treated early, the prognosis for people with trachoma is excellent. Although no vaccine is available, the disease is preventable. For instance, trachoma virtually disappeared in the United States by the 1950s due to improved sanitation and living conditions. The disease has also almost disappeared in certain countries, such as Morocco, where health organizations have been active in public education and have helped promote therapies known to cure the disease.
Untreated trachoma can lead to blindness. The World Health Organization estimates that about 80 million people worldwide have contracted trachoma, and of them, about 8 million are visually impaired. Most of those affected live in sub-Saharan Africa, parts of Asia and the Middle East.
If you're traveling to parts of the world where trachoma is endemic, be sure to practice good hygiene to prevent infection.
The cause of trachoma is certain subtypes of Chlamydia trachomatis, a bacterium that can also cause the sexually transmitted disease chlamydia.
Trachoma spreads through contact with discharge from the eyes or nose of an infected person. Hands, clothing, towels and insects can all be routes for transmission. In the world's developing countries, flies are a major means of transmission.
Risk Factor :
Factors that increase your risk of contracting trachoma include :
- Poverty. Trachoma is primarily a disease of extremely poor populations.
- Crowded living conditions. Families living in close contact are at greater risk of spreading infection.
- Sanitation. Poor hygienic conditions facilitate spread of the disease.
- Age. In areas where the disease is endemic, it's most common in children ages 3 to 5.
- Sex. Women contract the disease at higher rates than men do. Women are also blinded up to three times more often than men are.
- Access to water. Households at greater distances from a water supply are more susceptible to infection.
- Flies. People living in areas with problems controlling the fly population may be more susceptible.
- Latrines. Populations without access to working latrines have a higher incidence of the disease.
Mild itching and irritation and a discharge from the eye containing mucus or pus are the principal signs and symptoms in the early stages of trachoma. Later symptoms include marked light sensitivity (photophobia), blurred vision and eye pain.
Young children are particularly susceptible to infection, but the disease progresses slowly, and the more painful symptoms may not emerge until adulthood.
The World Health Organization has identified a grading system with five stages in the development of trachoma. The stages are :
- Inflammation — follicular. The infection is just beginning. Five or more follicles — small bumps that contain lymphocytes, a type of white blood cell — are visible with magnification on the inner surface of the upper eyelid (conjunctiva).
- Inflammation — intense. In this stage, the eye is now highly infectious and becomes irritated, with a thickening or swelling of the upper eyelid.
- Eyelid scarring. Repeated infections lead to scarring of the inner eyelid; the scars often appear as white lines when examined with magnification. The eyelid may become distorted and may turn in (entropion).
- Trichiasis, or ingrown eyelashes. The scarred inner lining of the eyelid continues to deform, causing the lashes to turn in so that they rub on and scratch the transparent outer surface of the eye (cornea). Only about 1 percent of people with trachoma develop this painful condition.
- Corneal clouding. The cornea becomes affected by an inflammation that is most commonly seen under the upper lid. Continual inflammation compounded by scratching from the in-turned lashes leads to clouding of the cornea. Secondary infection can lead to development of ulcers on the cornea and eventually partial or complete blindness.
All the signs of trachoma are more severe in the upper lid than in the lower lid. With advanced scarring, the upper lid may show an S-shaped curve. In addition, the lubricating glandular tissue in the lids — including the tear-producing glands (lacrimal glands) — can be affected. This can lead to extreme dryness, aggravating the problem even more.
Most people with trachoma in its initial stages display no signs or symptoms. In areas where the disease is endemic, a doctor can diagnose trachoma through a clinical examination or through sending a sample of bacteria from your eyes to be cultured and tested in a laboratory.
One episode of infection with Chlamydia trachomatis is easily treated with early detection and use of antibiotics. However, repeated infection can lead to complications, including :
- Scarring of the inner eyelid
- Eyelid deformities
- Inward folding of the eyelid (entropion)
- Ingrown eyelashes
- Corneal scarring or cloudiness
- Partial or complete vision loss
Treatment options for trachoma depend on the stage of development.
In the early stages of trachoma, treatment with antibiotics alone may be enough to eliminate the infection. An older course of treatment that doctors once favored involved applying a topical tetracycline eye ointment over a six-week period. However, oral antibiotics have been shown to be more effective. Currently the most common antibiotic treatment is a single dose of azithromycin (Zithromax).
Treatment of later stages of trachoma — including painful eyelid deformities — may require surgery. In eyelid rotation surgery (bilamellar tarsal rotation), a doctor makes an incision in the scarred lid and rotates the eyelashes away from the cornea. The procedure limits the progression of corneal scarring and can improve eyesight. Generally, this procedure can be performed on an outpatient basis. The procedure takes less than 15 minutes and has a good long-term success rate.
If the cornea has become clouded enough to seriously impair vision, corneal transplantation is an option that offers some hope of improved vision; frequently, however, the results are not good.
After antibiotic treatment or surgery, reinfection is always a concern. For your protection and for the safety of others, be sure that family members or others you live with are screened and, if necessary, treated for trachoma.
Hygiene is critical in preventing trachoma. Proper practices include :
- Face washing. Keeping faces clean, especially children's, can help break the cycle of reinfection.
- Controlling flies. Reducing fly populations can help eliminate a major source of transmission.
- Proper waste management. Properly disposing animal and human waste can eliminate breeding grounds for flies.
- Improved access to water. Having a fresh water source nearby can help improve hygienic conditions.
Community intervention is often needed for effective prevention. This includes education on the need for improved water quality and personal hygiene.