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
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 http://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 http://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 http://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: http://www.sightsavers.org.
Tish Davidson, A.M.