trachoma(redirected from diffuse trachoma)
Also found in: Dictionary, Thesaurus, Medical.
trachoma(trəkō`mə), infection of the mucous membrane of the eyelids caused by the bacterium Chlamydia trachomatis. Trachoma affects at least 86 million people worldwide. An estimated 1.9 million people are blind or visually impaired 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, typically occurring in the poorest, most rural areas. 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 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. A number of countries have made significant progress against the disease, and some have eliminated it entirely.
a chronic infectious disease of the eyes marked by inflammation and thickening of the conjunctiva and subsequent scarring. The causative agents are chlamydiae, microorganisms similar to viruses, that reproduce in the epithelial cells of the conjunctiva and often form colonies enveloped in a covering. The disease is transmitted from infected to noninfected eyes by flies, the hands, and such objects as handkerchiefs, towels, and washbowls contaminated by pus, mucus, or tears. The incubation period lasts from seven to 14 days. Both eyes are generally affected.
Trachoma can be divided into four clinical stages. The first stage is marked by inflammatory infiltration of conjunctival tissues, the appearance of semitransparent follicles in this tissue’s retrotarsal folds and on the eyelid conjunctiva, and the discharge of mucus and pus. In the second stage, these symptoms intensify and signs of scarring appear. The third stage is marked by severe scarring, and the fourth, by permanent scarring, the arrest of follicle formation and tissue infiltration, and cessation of the disease itself.
If untreated, trachoma may persist for years and even decades. The cornea often becomes affected by pannus, and a suppurative ulcer of the cornea may occur if trachoma is accompanied by a secondary infection. The spread of infiltration and scarring to the eyelid and tendons causes ptosis of the upper eyelid or inversion of the eyelids, resulting in ingrowing eyelashes (trichiasis) and traumatic injury to the cornea. Scarring of the conjunctival sac may lead to the fusing of the conjunctiva with the eyeball. Xerophthalmia is a possible consequence of trachoma. The extent of visual impairment is directly related to the degree of injury to the cornea.
Trachoma is treated with antibiotics, sulfanilamides, and such enzymes as hyaluronidase. Surgery is indicated in trichiasis and some other complications and consequences of trachoma.
The incidence of trachoma is determined by the economic and cultural level of a given area and the prevailing sanitary conditions. The disease is most widespread in Asia and Africa. Trachoma is prevented by early detection, systematic treatment, and the promotion of habits of personal hygiene. The disease is no longer common in the USSR owing to the effectiveness of the measures used to control it.
REFERENCESChirkovskii, V. V. Trakhoma, 6th ed. Moscow, 1953.
Mnogotomnoe rukovodstvo po glaznym bolezniam, vol. 2, book 1.
Moscow, 1960. Page 77. Kovalevskii, E. I. Detskaia oftal’mologiia. Moscow, 1970. Page 130. System of Ophthalmology, vol. 8. London, 1965. Page 258.
M. L. KRASNOV