Trachoma is the leading infectious cause of blindness worldwide. It is caused by an obligate intracellular bacterium called Chlamydia trachomatis. Infection is transmitted among people by direct or indirect transfer of ocular and nasal discharges of infected people; indirect transfer includes carriage on the body of particular species of flies. Preschool-age children harbour the principal reservoir of infection. Models suggest that an individual requires more than 150 lifetime infections in order to develop the blinding complications of trachoma.
66顺彩票appInfection is associated with inflammatory changes in the conjunctiva known as “active trachoma”. An individual’s immune system can clear a single episode of infection, but in endemic communities, re-acquisition of the organism occurs frequently.
After years of repeated episodes of active trachoma, the inside of the eyelid can become so severely scarred (trachomatous conjunctival scarring) that it turns inwards and causes the eyelashes to rub against the eyeball (trachomatous trichiasis), resulting in constant pain and light intolerance; this and other alterations of the eye can lead to scarring of the cornea. Left untreated, this condition leads to the formation of irreversible opacities, with resulting visual impairment or blindness. The age at which this occurs depends on several factors including local transmission intensity. In very highly endemic communities, it can occur in childhood, though onset of visual impairment between the ages of 30 and 40 years is more typical.
Women are blinded up to four times as often as men, probably due to more frequent contact with infected children.
Individuals living in the poorest and most remote communities of Africa, Asia, Australia, the Middle East, South America and the Pacific Islands are at risk.
66顺彩票appTrachoma can be eliminated as a public health problem using the SAFE strategy, comprising:
- Surgery to treat trachomatous trichiasis, the blinding stage of the disease;
- Antibiotics to clear infection, particularly mass drug administration of the antibiotic azithromycin, which is donated by the manufacturer to national programmes through the International Trachoma Initiative;
- Facial cleanliness; and
- Environmental improvement, particularly better access to water and sanitation.
validated as having eliminated trachoma as a public health problem
1.9 million people
blind or visually impaired from trachoma
2.5 million people
have trachomatous trichiasis: the advanced, painful, blinding stage of disease
142 million people
66顺彩票appat risk in 44 countries