The World Health Organization (WHO) has updated its fact sheet on Trachoma.
Trachoma is caused by an obligate intracellular bacterium called Chlamydia trachomatis.
The infection is transmitted through contact with eye and nose discharge of infected people, particularly young children who harbour the principal reservoir of infection. It is also spread by flies which have been in contact with the eyes and noses of infected people.
Trachoma is the leading infectious cause of blindness worldwide, and causes about 1.4% of all blindness worldwide.
It is known to be a public health problem in 37 countries, and is responsible for the blindness or visual impairment of about 1.9 million people.
Based on April 2018 data, 158 million people live in trachoma endemic areas and are at risk of trachoma blindness.
Overall, Africa remains the most affected continent, and the one with the most intensive control efforts.
In 2017, in the 22 countries of WHO’s Africa Region in which trachoma is known to be a public health problem, more than 226 000 people with trichiasis were given operations (95% of the global total operated on for trichiasis), and more than 79 million people were treated with antibiotics (95% of the global total given antibiotics for trachoma).
Transmission and Clinical Features
Infection spreads through personal contact (via hands, clothes or bedding) and by flies that have been in contact with discharge from the eyes or nose of an infected person.
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. 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.
Blindness from trachoma is irreversible.
Environmental risk factors influencing the transmission of the disease include:
- poor hygiene
- crowded households
- water shortage
- inadequate latrines and sanitation facilities.
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.
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.
The economic cost in terms of lost productivity from blindness and visual impairment is estimated at US$ 2.9–5.3 billion annually, increasing to US$ 8 billion when trichiasis is included.
Prevention and Control
The World Health Assembly adopted resolution WHA51.11 in 1998, targeting the global elimination of trachoma as a public health problem.
The elimination strategy is encapsulated by the acronym “SAFE”:
- Surgery for advanced disease,
- Antibiotics to clear C. trachomatis infection,
- Facial cleanliness and
- Environmental improvement to reduce transmission.
In 2017, more than 231 000 people received surgical treatment for advanced disease, and 83.5 million people were treated with antibiotics for trachoma. Global-level antibiotic coverage in 2017 was 52% – up from 30% in 2015.
Link to the updated fact sheet:
Link to WHO page on blindness and vision impairment prevention:
Link to previous article on blindness and visual impairment: