Trachoma
沙眼
Trachoma is the leading infectious cause of blindness worldwide. It is caused by an obligate intracellular bacterium called Chlamydia trachomatis. The infection is transmitted by direct or indirect transfer of eye and nose discharges of infected people, particularly young children who harbour the principal reservoir of infection. These discharges can be spread by particular species of flies.
沙眼是全球盲症的主要感染性致病原因。它由一种称为沙眼衣原体的专性细胞内细菌引起。沙眼感染是通过受感染者，特别是作为主要感染贮源的幼儿的眼和鼻分泌物的直接或间接转移来传播的。这些分泌物可以通过特定种类的飞蝇传播。
Epidemiology and clinic features
流行病学和临床特征
In areas where trachoma is endemic, active (inflammatory) trachoma is common among preschool-aged children, with prevalence rates which can be as high as 60–90%. Infection becomes less frequent and shorter in duration with increasing age. Infection is usually acquired when living in close proximity to others with active disease, and the family is the main setting for transmission. An individual’s immune system can clear a single episode of infection, but in endemic communities, re-acquisition of the organism occurs frequently.
在沙眼流行的地区，活动性沙眼在学龄前儿童中极为常见，患病率可高达60-90%。随着年龄的增大，感染的频次降低，持续时间减短。受到感染常常是由于与患有这种活动性疾病的人有近距离的生活接触，家庭常是主要的传播单位。人们的免疫系统可使单次感染得到清除，但在疾病流行社区经常会出现病原体反复感染情况。
After years of repeated infection, 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.
经过数年的反复感染，眼睑内部会形成严重疤痕(结膜疤痕)，使眼睑向内深入，眼睑边缘的睫毛摩擦眼球(倒睫)，产生持续疼痛和畏光;这加上其他的眼部病变会导致角膜产生疤痕。如果不加治疗，这种病症会形成无法好转的角膜混浊，发展成视力损害或盲症。
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.
该病发病年龄取决于若干因素，包括本地传播密度。在呈极为高度流行的社区，尽管30至40岁人群发生视力损害较为典型，但也可发生在儿童期。
Visual impairment or blindness results in a worsening of the life experience of affected individuals and their families, who are normally already amongst the poorest of the poor. Women are blinded up to 4 times as often as men, probably due to their close contact with infected children and their resulting greater frequency of infection episodes.
患者个人及其家庭通常已经处于贫穷的最底层，视力损害或盲症使他们的生活雪上加霜。可能由于与受感染儿童密切接触并由此导致感染发作更频繁，妇女致盲的几率通常高达男性的四倍。
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