Trachoma

Definition

Trachoma, also called granular conjunctivitis or Egyptian ophthalmia, is a contagious, chronic inflammation of the mucous membranes of the eyes, caused by the bacterium Chlamydia trachomatis. It is characterized by swelling of the eyelids, sensitivity to light, and eventual scarring of the conjunctiva and cornea of the eye.

Description

Trachoma is a disease associated with poverty and unhygienic conditions. It is most common in hot, dry, dusty climates in the developing world where water is scarce and sanitation is poor. Trachoma is the most common infectious cause of blindness in the world. It has two stages. The first stage is active infection of the conjunctiva by the bacterium C. trachomatis. The conjunctiva is the clear mucous membrane that lines the inside of the eyelid and covers the white part (sclera) of the eye. This stage is highly contagious.

Acquiring trachoma does not provide immunity against re-infection, so repeat infections are the norm in many communities where the disease circulates continuously among family members. The frequency of active infection peaks in children ages three to five. In some communities, as many as 90 percent of children under age five are actively infected.

The second stage involves damage to the cornea, the transparent covering of the front of the eye. After repeated infections, the eyelids swell and the eyelashes begin to turn inward so that they scratch the cornea every time the individual blinks. This scratching is painful, and it scars the cornea, eventually resulting in the cornea becoming opaque. Individuals are often blind by middle age. Repeated, extended, untreated periods of infection are required for blindness to occur. An occasional, treated infection does not result in blindness.

Transmission

C. trachomatis is spread through direct contact. Infected young children serve as a reservoir of infection. The bacteria are then transmitted by close physical contact with family members and other caregivers. The bacteria are also spread through shared blankets, pillows, and towels. The bazaar fly Musca sorbens lays its eggs in human feces that can be contaminated with trachoma bacteria. These flies pick up bacteria on their bodies and can transmit them to humans.

Certain conditions promote the spread of trachoma bacteria. These include:

• poor personal hygiene
• poor body waste and trash disposal
• insufficient water supply for washing
• shared sleeping space
• close association with domestic animals

Demographics

Trachoma is widespread and present in a high percentage of the population in many parts of Africa, Iraq, Afghanistan, Burma, Thailand, and Viet Nam. Pockets of high trachoma infection also exist in southern Mexico, eastern Brazil, Ecuador, North Africa, India, China, Siberia, Indonesia, New Guinea, Borneo, and in Aboriginal communities in central Australia. Although trachoma is rare in developed countries, it is occasionally found in the United States in some Native American communities and in parts of Appalachia.

The greatest risk for contracting trachoma is having a family member with the disease. Although the disease shows no gender preference, two to three times more women eventually become blind than men, probably because they are the primary caretakers of small children who are infected. The active stage of the disease is most prevalent in children ages three to five. Blindness is most common in middle age. The World Health Organization (WHO) estimates that as of the early 2000s, between 360 and 500 million people are affected by trachoma worldwide and that six million people are blind because of the disease. In some heavily infected areas, up to 25 percent of the population becomes blind from this infection.

Causes and symptoms

The early symptoms of trachoma include the development of follicles (small sacs) on the conjunctivae of the upper eyelids; pain ; swollen eyelids; discharge; tearing; and sensitivity to light. If the infection is not treated, the follicles develop into large yellow or gray pimples, and small blood vessels develop inside the cornea. In most cases, both eyes are infected. The incubation period is about one week.

Repeated infections eventually lead to contraction and turning-in of the eyelids. The eyelashes then scratch the corneas and conjunctivae, every time the individual blinks. This scratching leads to scarring of the cornea, eventual blockage of the tear ducts, and blindness.

When to call the doctor

U.S. parents should call the doctor if they notice any discomfort or discharge from their child's eye, especially if they have recently traveled in areas where trachoma is common.

Diagnosis

Diagnosis is based on a combination of the patient's history (especially living or traveling in areas with high rates of trachoma) and examination of the eyes. The doctor looks for the presence of follicles or scarring. In developed countries where laboratory facilities are available, the doctor takes a small sample of cells from the child's conjunctivae and examines it, following a procedure called Giemsa staining, to confirm the diagnosis. In underdeveloped countries where medical resources are scarce, diagnosis is made based on an examination only.

Treatment

The preferred treatment is the oral antibiotic azithromycin (Zithromax). This medicine has replaced treatment with other antibiotics (usually tetracyclines ), because only a single dose of azithromycin is required to clear the infection. Oral single dose treatment increases compliance. Everyone in the family should be treated at the same time, whether they show clinical signs of the disease or not, because transmission among family members is so common.

Individuals with complications from untreated or repeated infections require surgery. Surgery can be used for corneal transplantation or to correct eyelid deformities. It does not, however, prevent re-infection.

Prognosis

The prognosis for full recovery is excellent if the individual is treated promptly. If the infection has progressed to the stage of follicle development, prevention of blindness depends on the size of the follicles, the presence of additional bacterial infections, and the development of scarring. The longer the period of infection, the greater the risk of corneal scarring and blindness.

KEY TERMS

Conjunctivitis —Inflammation of the conjunctiva, the mucous membrane covering the white part of the eye (sclera) and lining the inside of the eyelids also called pinkeye.

Cornea —The clear, dome-shaped outer covering of the eye that lies in front of the iris and pupil. The cornea lets light into the eye.

Prevention

Trachoma is a preventable disease. Prevention depends upon good hygiene and public health. The WHO has developed a program called SAFE, which aims to prevent blindness caused by trachoma. The elements of the program are surgery, antibiotic treatment, facial cleansing and improved personal hygiene, and environmental improvements. Despite this prevention program, permanent gains in controlling trachoma have been elusive.

Parental concerns

In the United States, parents should check with the Centers for Disease Control (available online at <www.cdc.gov>) for advisories about the prevalence of trachoma if they are planning to travel with their children to underdeveloped countries.

Resources

BOOKS

Bailey, Robin. "Eye Infections in the Tropics." In Infectious Diseases, 2nd ed. Edited by Jonathon Cohen and William Powderly. St. Louis: Mosby, 2003.

O'Brien, Terrence P. "Conjunctivitis." In Conn's Current Therapy, 56th ed. Edited by Robert E. Rakel. Philadelphia: W. B. Saunders Co., 2004.

WEB SITES

Mabey, Denise, and Hugh Taylor. "Trachoma." eMedicine Medical Library, April 17, 2001. Available online at <www.emedicine.com/0ph/topic118.htm> Accessed August 1, 2004.

"Ophthalmologic Disorders: Trachoma." In The Merck Manual of Diagnosis and Therapy, 17th ed. Edited by Robert Berkow. Rahway, NJ: Merck Research Laboratories, 1999–2004. Available online at <www.merck.com/mrkshared/mmanual/home.jsp> (accessed October 18, 2004).

ORGANIZATIONS

Sight Savers International. c/o Chapel & York, PMB #293, 601 Pennsylvania Avenue, NW, Suite 900, South Building, Washington, DC 20004. Web site: <www.sightsavers.org>.

Tish Davidson, A.M.

Trachoma

Definition

Trachoma, which is also called granular conjunctivitis or Egyptian ophthalmia, is a contagious, chronic inflammation of the mucous membranes of the eyes, caused by Chlamydia trachomatis. It ischaracterized by swelling of the eyelids, sensitivity to light, and eventual scarring of the conjunctivae and corneas of the eyes.

Description

Trachoma is a major cause of blindness in the world. It is found in the Far East, as well as countries with desert climates. In the United States, it is most common among certain Native Americans and in parts of Appalachia. The infection is highly contagious in its early stages. Blindness results from recurrent untreated infections.

The conjunctiva is the clear mucous membrane that lines the inside of the eyelid and covers the white part (sclera) of the eye. Conjunctivitis is an inflammation of the conjunctiva.

Causes and symptoms

Trachoma is caused by C. trachomatis, a parasitic organism closely related to bacteria. It is transmitted by insects, by hand-to-eye contact, or by the sharing of infected handkerchiefs or towels. The incubation period is about a week.

The early symptoms of trachoma include the development of follicles (small sacs) on the conjunctivae of the upper eyelids, pain, swollen eyelids, a discharge, tearing, and sensitivity to light. If the infection is not treated, the follicles develop into large yellow or gray pimples, and small blood vessels develop inside the cornea. In most cases, both eyes are infected.

Repeated infections eventually lead to contraction and turning-in of the eyelids, scarring of the corneas and conjunctivae, eventual blockage of the tear ducts, and blindness.

Diagnosis

Diagnosis is based on a combination of the patient's history (especially living or traveling in areas with high rates of trachoma) and examination of the eyes. The doctor will look for the presence of follicles or scarring. He or she will take a small sample of cells from the patient's conjunctivae and examine them, following a procedure called Giemsa staining, to confirm the diagnosis.

Treatment

Treatment of early-stage trachoma consists of four to six weeks of antibiotic treatment with tetracycline, erythromycin, or sulfonamides. Antibiotics should be given without waiting for laboratory test results. Treatment may combine oral medication with antibiotic ointment applied directly to the eyes. A single-dose treatment with azithromycin is an alternative method. Tetracyclines should not be given to pregnant women or children below the age of seven years.

Patients with complications from untreated or repeated infections are treated surgically. Surgery can be used for corneal transplantation or to correct eyelid deformities.

Prognosis

The prognosis for full recovery is excellent if the patient is treated promptly. If the infection has progressed to the stage of follicle development, prevention of blindness depends on the severity of the follicles, the presence of additional bacterial infections, and the development of scarring.

Prevention

There are vaccines available that offer temporary protection against trachoma, but there is no permanent immunization. Prevention depends upon good hygiene and public health measures:

• seek treatment immediately if a child shows signs of eye infection, and minimize his or her contact with other children
• teach children to wash hands carefully before touching their eyes
• protect children from flies or gnats that settle around the eyes
• if someone has trachoma (or any eye infection), do not share towels, pillowcases, etc; Wash items well
• if medications are prescribed, follow the doctor's instructions carefully

Resources

BOOKS

Riordan-Eva, Paul, et al. "Eye." In Current Medical Diagnosis and Treatment, 1998, edited by Stephen McPhee, et al., 37th ed. Stamford: Appleton & Lange, 1997.

KEY TERMS

Conjunctivitis— Inflammation of the conjunctivae, which are the mucous membranes covering the white part of the eyeball (sclera) and lining the inside of the eyelids.

Cornea— The transparent front part of the eye that allows light to enter.

Ophthalmia— Inflammation of the eye. Usually severe and affecting the conjunctiva. Trachoma is sometimes called Egyptian ophthalmia.

TRACHOMA

Trachoma is a virulent form of conjunctivitis caused by Chlamydia trachomatis, a bacterial organism transmitted by flies that crawl into the eyes of small children. Direct transmission of the organism from fingers, damp towels, and other objects also occurs. Characteristically, reinfection is frequent in endemic regions; this leads to severe scarring and contractures, especially of the upper eyelid, and also causes blood vessels to invade the cornea, rendering it opaque. These effects of recurrent infection make trachoma a leading cause of blindness in those parts of the world where the condition is prevalent. These are predominantly poor, rural areas in hot, dry countries such as some nations in the Middle East and in arid regions of North Africa, India, Pakistan, and inland Australia.

Trachoma is responsible for about 6 million out of a total of 20 million cases of blindness worldwide, and it causes impaired vision in about 140 million people. Determined efforts have greatly reduced the incidence of new cases in the last two decades of the twentieth century, however. It is rare in industrially developed nations with good hygiene and effective fly control measures—such as screened windows. Trachoma is an exclusively human infection, so if vulnerable populations can be protected from exposure (e.g., if flies can be reduced or eliminated), transmission will cease and the infection can be prevented. These tactics have worked well in many regions, including among Australian Aborigines, where the prevalence was very high until control programs were established.

Control was achieved in Australia by an aggressive campaign led by Dr. Ida Mann, who devoted her life to this cause. Her methods comprised topical application of antiseptic and antibiotic eyedrops, disinfection and face washing, education about personal hygiene, and fly control programs. Initially this was a mass campaign, and it was reduced to individual case management as endemic conjunctivitis was brought under control. The same tactics have worked in the Middle East (e.g., among nomadic Bedouin populations in Saudi Arabia), and they are working well in endemic regions of India and Pakistan. The World Health Organization, with strong support from several foundations and nongovernmental organizations devoted to prevention of blindness, aspires to eliminate trachoma by 2020.

John M. Last

(see also: Vision Disorders )

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.

trachoma (tră-koh-mă) n. a chronic contagious eye disease – a severe form of conjunctivitis caused by the bacterium Chlamydia trachomatis – that is common in some hot countries. If untreated, the conjunctiva becomes scarred and shrinks, causing trichiasis; blindness can be a late complication. Treatment with tetracyclines is effective in the early stages of the disease.

trachoma Chronic eye infection caused by the microorganism Chlamydia trachomatis, characterized by inflammation of the cornea with the formation of pus. A disease of dry, tropical regions, it is the major cause of blindness in the developing world.