Trachoma is a type of bacterial eye infection. The condition is a leading cause of preventable blindness worldwide, although it's rare in developed countries such as the UK.
Trachoma usually first affects young children, causing mild irritation in the eyes and a discharge of pus and/or mucus.
Repeated trachoma infections can lead to severe symptoms, including:
eye pain – which is often severe
intense itchiness in the eyes caused by the eyelids turning inwards and the eyelashes rubbing on the eyeball
As the condition progresses, the eyelashes will scratch the cornea (the transparent layer at the front of the eye) and scar it. This is known as trichiasis.
The scarring causes a person's vision to become increasingly cloudy and, left untreated, it may eventually lead to complete loss of vision.
What causes trachoma and how is it spread?
Trachoma is caused by a bacterium called Chlamydia trachomatis. The bacteria cause the lining on the inside of the eyelids (conjunctiva) to become inflamed, and may eventually, after repeated infections over many years, cause the eyelids to turn inwards and the eyelashes to touch the eyeball.
A single infection doesn't pose a serious threat to the eyes, but repeated infections can cause extensive inflammation of the conjunctiva and scarring of the cornea.
The bacteria are spread in the discharge that comes from the eyes, and in some cases the nose, of someone with the condition. The discharge can be spread to other people's eyes by:
an infected person touching their eyes or nose and then touching other people
sharing clothes, bed linen, towels and flannels
flies – which can transmit small droplets of the discharge to other people
Trachoma bacteria thrive in environments where:
there are high levels of overcrowding – for example, where all family members sleep in the same room
there's limited access to clean water
there's limited access to washing facilities, such as showers or baths
there's a large fly population
there's limited access to healthcare services
Who's affected by trachoma?
Trachoma is a condition directly related to poverty. Improvements in health and hygiene mean it's now rarely a problem in the UK and the rest of the developed world.
Trachoma is usually only found in the very poorest communities – typically villages and slums in hot, dusty climates where hygiene levels are poor and access to water and sanitation is limited. The majority of cases occur in Africa, the Middle East and parts of Asia.
The World Health Organization (WHO) estimates that there are about 50 million people in the world with trachoma who need treatment, and around two million people who are blind because of the condition.
Trachoma can usually be diagnosed by examining a person's upper eyelids after flipping them over. If there's any doubt, the eye discharge can be tested for the Chlamydia trachomatis bacteria.
Trachoma is simple to treat. However, it's highly contagious and the risk of re-infection is high. As people with trachoma tend to live in areas where the infection is widespread, entire communities usually need to be treated to stop it spreading.
The WHO is aiming to eliminate blinding trachoma by 2020, using a community-focused initiative called "SAFE". This stands for:
Surgery – to repair damage to the eyelids
Antibiotics – to treat the infection
Face washing – to prevent the spread of infection
Environmental changes – such as providing access to clean water and suitable sanitation to help reduce the risk of re-infection
Face washing and environmental changes
Regular face washing removes the contagious discharge from the eyes and reduces the risk of the infection spreading through physical contact and flies. However, people are often reluctant to wash their faces regularly if clean water is limited.
Improving access to clean water and washing facilities, and reducing the local fly population, can help to limit the spread of infection.
Much of this work is carried out by charities, voluntary organisations and other non-governmental organisations (NGOs), such as:
Sightsavers – an international charity that's working to eliminate conditions that can cause blindness
WaterAid – a charity that seeks to provide clean water and safe sanitation facilities to the world's poorest people
A single dose of the antibiotic azithromycin, given by mouth (orally), is an effective treatment for trachoma.
WHO recommends that if 10% or more of the children in a community have trachoma, everyone in the community should be treated with one dose of azithromycin.
Surgery will be needed in cases of trachoma where scarring of the eyelids is causing the eyelashes to turn inwards.
During surgery, a cut is made in the upper eyelid and the eyelashes are turned away from the cornea. It's a relatively straightforward procedure carried out under local anaesthetic, and takes around 15 minutes to complete.
Where there's visual impairment, it may be possible to restore some vision with a cornea transplant. This involves removing the damaged corneas and replacing them with corneas from a suitable donor. However, access to this type of surgery is usually unavailable in places where trachoma is widespread.
Advice for travellers
Travellers from the UK are only at risk of developing trachoma if they're planning to live or work for a long time in very poor communities in the developing world – for example, as aid workers.
However, even if someone living and working in a community where trachoma is a problem were to develop the infection, it's highly unlikely that they would have the repeated infections that can cause blindness.