Mapping the Decline of Trachoma
What is Trachoma?
Trachoma is an eye disease caused by specific strains of the bacterium Chlamydia trachomatis.
These bacteria are infectious and can spread between people through touching secretions from the eyes or nose or from contaminated items like clothing. It can also be spread via flies, especially some species that are attracted to human eyes.
The bacteria infect the conjunctiva — the thin, pink, soft inner layer of the eyelids — which leads to inflammation.
If people have many repeated infections, the inflammation scars the eyelids, which begin to turn inwards. The eyelashes then turn inwards and scratch the cornea (the clear surface of the eyes). In severe cases, this causes the cornea to become clouded, which eventually results in permanent blindness.
Trachoma is more common in rural areas and spreads easily between people living together, especially in places with poor sanitation and hygiene. While it mainly infects children, the later stages of scarring and blindness develop in adulthood.
Trachoma is a very painful disease. Aside from the risk of blindness, it causes blurry vision, red and swollen eyes, pain while blinking or sleeping, and vision loss. As a consequence, people are more prone to accidents, have problems with daily life and work, and experience social stigma.
It’s estimated that more than 400,000 people globally were blind as a result of trachoma in 2021. As you can see in the chart below, it is a particularly common cause of blindness in Africa and South Asia.
Trachoma has Declined Greatly Over Time
Trachoma is an ancient disease that has been described in ancient Egypt, China, and Greece. It is less common outside tropical regions, but as recently as the 1950s, the World Health Organization reported that it was found in almost every country in the world.
Trachoma declined significantly in many richer countries over the twentieth century with improvements in clean water, sanitation, garbage collection systems, insect control programs, and the development of effective antibiotics.
Although it’s still widespread in poorer countries, great progress has been made against the disease in the last few decades.
The maps below show the prevalence of early stages of trachoma in African children, according to surveys conducted between 1996 and 2021.
In the first surveys, which were mostly conducted in the early 2000s, more than 10% of children in many areas had trachoma. In some, more than half of children had the disease.
However, by the most recent surveys, the prevalence of trachoma shrunk greatly. Of all the areas surveyed, 92% had begun using mass antibiotic treatment programs, and 77% of areas managed to reduce the prevalence of trachoma by 50% or more.