WHO updates fact sheet on Trachoma (5 April 2019)

The World Health Organization (WHO) has updated its fact sheet on Trachoma.

Background Information:

Trachoma is a disease of the eye caused by infection with the bacterium Chlamydia trachomatis.

The infection is transmitted by direct or indirect transfer of eye and nose discharges of infected people, particularly young children who harbour the principal reservoir of infection. These discharges can be spread by particular species of flies.

Elimination of trachoma as a public health problem is defined as:

  1. a prevalence of trachomatous trichiasis “unknown to the health system” of <0.2% in adults aged ≥15 years (approximately 1 case per 1000 total population), and
  2. a prevalence of trachomatous inflammation—follicular in children aged 1–9 years of <5%, sustained for at least two years in the absence of ongoing antibiotic mass treatment, in each formerly endemic district; plus
  3. the existence of a system able to identify and manage incident trachomatous trichiasis cases, using defined strategies, with evidence of appropriate financial resources to implement those strategies.

Key Messages:

Trachoma is the leading infectious cause of blindness worldwide. 

It is a public health problem in 37 countries of Africa, Central and South America, Asia, Australia and the Middle East, and is responsible for the blindness or visual impairment of about 1.9 million people, and causes about 1.4% of all blindness worldwide.

Based on April 2018 data, 158 million people live in trachoma endemic areas and are at risk of trachoma blindness.

Blindness from trachoma is irreversible.

In areas where trachoma is endemic, active (inflammatory) trachoma is common among preschool-aged children, with prevalence rates which can be as high as 60–90%. Infection becomes less frequent and shorter in duration with increasing age.

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.

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.

Environmental risk factors influencing the transmission of the disease include:

  • inadequate hygiene
  • crowded households
  • inadequate access to water
  • inadequate access to and use of sanitation.

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.

The World Health Assembly adopted resolution WHA51.11 in 1998, targeting the global elimination of trachoma as a public health problem.

Elimination programmes in endemic countries are being implemented using the WHO-recommended SAFE strategy. This consists of:

  • Surgery to treat the blinding stage (trachomatous trichiasis);
  • Antibiotics to clear infection, particularly mass drug administration of the antibiotic azithromycin, which is donated by the manufacturer to elimination programmes, through the International Trachoma Initiative;
  • Facial cleanliness; and
  • Environmental improvement, particularly improving access to water and sanitation.

As of 4 April 2019, 13 countries had reported achieving elimination goals. These countries are:

  1. Cambodia,
  2. China,
  3. Gambia,
  4. Ghana,
  5. Islamic Republic of Iran,
  6. Iraq,
  7. Lao People’s Democratic Republic,
  8. Mexico,
  9. Morocco,
  10. Myanmar,
  11. Nepal,
  12. Oman and
  13. Togo.

Eight of those countries – Cambodia, Islamic Republic of Iran, Lao People’s Democratic Republic, Ghana, Mexico, Morocco, Nepal and Oman – had been validated by WHO as having eliminated trachoma as a public health problem.

Useful Links:

Link to the updated fact sheet:

https://www.who.int/news-room/fact-sheets/detail/trachoma

Link to World Health Assembly WHA51.11 Resolution:

https://www.who.int/blindness/causes/WHA51.11/en/

Link to WHO page on Blindness and vision impairment:

https://www.who.int/blindness/en/

 

 

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