Leading cause of infectious blindness

Trachoma is a bacterial infection that causes a roughening of the inner surface of the eyelids. This roughening can lead to pain in the eyes, breakdown of the outer surface or cornea of the eyes, and eventual blindness. Trachoma is the leading preventable cause of blindness worldwide. It’s very contagious and most of the time affects both eyes. Blindness from trachoma is irreversible.

Globally, about 80 million people have an active infection. In some areas, infections may be present in as many as 60–90% of children. The disease is an issue in 44 countries and the cause of decreased vision in 2.2 million people, of whom 1.2 million are completely blind.

What causes Trachoma

Trachoma is caused by the bacterium Chlamydia trachomatis, and easily spread through direct personal contact, shared towels and cloths, and flies that have come in contact with the eyes or nose of an infected person. With repeated episodes of infection over many years, the eyelashes may be drawn in so that they rub on the surface of the eye, with pain and discomfort and permanent damage to the cornea.

Different types of C. trachomatis cause different diseases. The most common strains cause disease in the genital tract, while other strains cause disease in the eye or lymph nodes. Serovars A through C cause trachoma.

Environmental factors that are associated with more intense transmission of Trachoma includes inadequate hygiene facilities, crowded households, inadequate access to clean water and inadequate access to and use of sanitation.

Where is Trachoma found

Trachoma is hyperendemic in many of the poorest and most rural areas of Africa, Central and South America, Asia, Australia and the Middle East. Among all, Africa remains the most affected continent. Within the continent, South Sudan and Ethiopia have the highest prevalence.It is a public health problem in 44 countries, and is responsible for the blindness or visual impairment of about 2.2 million people worldwide.

Australia is the only developed country that has trachoma.

Based on March 2020 data, 137 million people live in trachoma endemic areas and are at risk of trachoma blindness.

The disease is one of the earliest known eye afflictions, having been identified in Egypt as early as 15 BC.

Image: Trachoma geographic distribution.

What are the symptoms of Trachoma

The bacterium has an incubation period of 6 to 12 days, after which the affected individual experiences symptoms of conjunctivitis. Without reinfection, the inflammation gradually subsides.

The conjunctival inflammation is called active trachoma and usually is seen in children, especially preschool children. It is characterized by white lumps in the undersurface of the upper eyelid.

At first, trachoma may cause mild itching and irritation of eyes and eyelids followed by swollen eyelids and pus draining from the eyes. The other symptoms may include small bumps on the inside of the eyelid sight, light sensitivity or photophobia, eye pain, eye redness and vision loss.

Photo: Eye with viral conjunctivitis.

How can Trachoma be prevented

Reinfection is always a concern if anyone is treated for trachoma either with antibiotics or surgery. For the protection and safety of others, be sure that family members or others you live with are screened and, if necessary, treated for trachoma.

Extra care in practicing good and proper hygiene practice may help in preventing infection. Good and proper hygiene practice includes breaking the cycle of reinfection by keeping faces and hands clean, eliminating a source of transmission by reducing fly population, reducing breeding grounds of flies by properly disposing animal and human waste and improving hygienic condition by having fresh water source.

How is Trachoma diagnosed

Trachoma is diagnosed through a physical examination of the eyes. Examination of the eye for clinical signs of trachoma involves careful inspection of the lashes, cornea, and limbus, then eversion of the upper lid, and inspection of the tarsal conjunctiva.

In general, the diagnosis of trachoma is made on clinical grounds. Laboratory testing is typically unavailable or unaffordable for clinical care in areas where trachoma is endemic. The infection can be confirmed by using Polymerase chain reaction (PCR) tests, such as the ones made available by the WoIDM.

Microscopy examination of stained conjunctiva scrapings for C. trachomatis inclusion bodies is the oldest method for detection of ocular infection but still very much in use.

How is Trachoma treated

Trachoma treatment options depend on the stage of the disease. In the early stages of trachoma, treatment with antibiotics alone may be enough to eliminate the infection. Azithromycin (single oral dose of 20 mg/kg) or topical tetracycline (1% eye ointment twice a day for six weeks). Azithromycin is preferred because it is used as a single oral dose.

Anyone who has been exposed to trachoma should also be treated preventatively to reduce the spread of trachoma.

Treatment of later stages of trachoma may require surgery.

Advanced stages where the cornea has become opaque will leave a person irreversibly blind.

Without intervention, trachoma keeps families in a cycle of poverty, as the disease and its long-term effects are passed from one generation to the next.

Edited by: Himanshu Arvind Kapadia

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