- Trachoma is estimated to be endemic in 53 countries and is responsible for the visual impairment of about 2.2 million people, of whom 1.2 million are irreversibly blind.
- Approximately 229 million people live in trachoma endemic areas and are at risk of infection.
- An estimated 47 million were treated with antibiotics in 2012 and 169 000 received surgical treatment.
- Infection spreads through personal contact (hands, clothing) and by flies that have been in contact with discharge from the eyes and nose of infected persons.
- With repeated episodes of infection over many years, chronic sequelae may occur, with pain and discomfort and permanently damage to the cornea of the eye, leading to irreversible blindness.
Trachoma is the leading cause of infectious blindness in the world. It is caused by an obligate intracellular micro-organism called Chlamydia trachomatis. The disease is transmitted through contact with eye and nose discharge of infected people, particularly young children who form the reservoir of infection. It is also spread by flies which have been in contact with the eyes and nose of infected people.
Clinical characteristics and morbidity
In areas where trachoma is endemic active trachoma is common among preschool-aged children, with prevalence rates which might be as high as 60-90%. The infection becomes less frequent and shorter in duration with increasing age. Infection is usually acquired through living in close proximity to a person with the active disease, and the family is the principal unit for transmission.
After years of repeated infection, the inside of the eyelid can become so severely scarred (conjuctival scarring) that it turns inwards and the eyelid border causes the eye-lashes to rub against the eyeball (trichiasis) resulting in severe discomfort and pain; this and other alterations of the eye can lead to the scarring of the cornea. Left untreated, this condition leads to the formation of irreversible opacities with resulting visual impairment and blindness typically between the ages 30-40.
Visual impairment and blindness results in a worsening of the life experience of affected individuals and their families, which are normally already among the poorest of the poor. Women are blinded 2 to 3 times more often than men, probably due to their close contact with affected children.
Environmental risk factors influencing the transmission of the disease include:
- poor hygiene;
- crowded households;
- water shortage; and
- inadequate latrines and sanitation facilities.
Trachoma is hyperendemic in many of the poorest and most rural areas of 53 countries of Africa, Asia, Central and South America, Australia and the Middle East.
It is responsible for approximately 1% of the world’s blindness and for the visual impairment of about 2.2 million people, of whom 1.2 million are irreversibly blind.
Overall, Africa remains the most affected continent and the one with the most intensive control efforts. In 2012, 47 million people were treated with antibiotics and 169 000 cases of trichiasis were operated in 29 endemic countries of WHO’s Africa Region.
A number of countries have reported achieving intervention goals, which signify a major milestone in the campaign to trachoma elimination and the move to post-endemic surveillance. These countries are: The Gambia, Ghana, Iran, Morocco, Myanmar, Oman and Viet Nam
Last year the United Kingdom’s Department for International Development provided funding to a project aiming to complete the mapping of trachoma endemic areas by 2015. The Australian Government Overseas Aid Programme is funding the elimination of blinding trachoma in the South-East Asia Region.
The burden of trachoma on affected individuals and communities is enormous. The economic cost in terms of lost productivity is estimated at between US$2.9 and US$ 5.3 billion annually, increasing to US$ 8 billion when trichiasis is included.
Prevention and control
Control programmes in endemic countries are being implemented through the WHO recommended SAFE strategy. This consists of:
- surgery to treat the blinding stage of the disease (trachomatous trichiasis or TT);
- antibiotics to treat infection from chlamydia trachomatis;
- facial cleanliness, to educate the at risk population on the preventive measures; and
- environmental improvements, such as providing access to safe water and improved sanitation.
Most endemic countries have agreed to accelerate the implementation of this strategy to achieve their respective elimination targets, all within the year 2020.
Data reported to WHO by Member States in 2012 shows that about 47 million people in endemic communities were treated with antibiotics to eliminate trachoma.
Elimination efforts need to continue to satisfy the target set by the World Health Assembly resolution (WHA 51.11), which is elimination of trachoma as a public health problem by 2020. Particularly important will be the full engagement of other sectors involved in sanitation and socioeconomic development
WHO adopted the SAFE strategy in 1996. Its mandate is to provide technical leadership and coordination to the international efforts aiming to eliminate trachoma as a cause of visual impairment. The recommended strategy is a combination of interventions implemented as an integrated approach.
In 1997, WHO launched the WHO Alliance for the Global Elimination of Trachoma by the year 2020 (GET 2020). GET 2020 is a partnership which supports country implementation of the SAFE strategy and the strengthening of national capacity through epidemiological assessment, monitoring, disease surveillance, project evaluation and resource mobilization.