Trachoma: blinding disease

Trachoma affects 128 million children and over twice as many adults. Globally, 84 million people suffer from active infection and nearly 8 million people are visually impaired as a result of this disease. Globally this disease results in considerable disability.
Infection of the inside of the eye causes scarring. This can eventually turn the eyelids inwards so that the eyelashes start to rub against the eye. This can cause blindness.

Trachoma is caused by Chlamydia trachomatis and it is spread by direct contact with eye, nose, and throat secretions from affected individuals, or contact with fomites (inanimate objects), such as towels and/or washcloths, that have had similar contact with these secretions. Flies can also be a route of mechanical transmission. Untreated, repeated trachoma infections result in entropion, a painful form of permanent blindness when the eyelids turn inward, causing the eyelashes to scratch the cornea. Children are the most susceptible to infection due to their tendency to easily get dirty, but the blinding effects or more severe symptoms are often not felt until adulthood. 

It is cheap to treat trachoma in its early stages, in later stages eyelid or corneal surgery may be required. The World Health Organisation notes that trachoma is associated with poor socioeconomic conditions, such as overcrowding, limited access to water and poor sanitation.

The table below shows the % of children suffering from trachoma in 2003.