London School of Hygiene & Tropical Medicine

The Global Trachoma Mapping Project (GTMP), launched in 2012 and completed in January 2016, is the largest infectious disease survey ever undertaken. The GTMP, which aimed to pinpoint accurately the world's trachoma endemic areas, was undertaken by more than 550 teams of trained surveyors collecting and transmitting data from 2.6 million people in 29 countries using Android smartphones. On average one person was examined every 40 seconds during the three-year project.

Experts from the London School of Hygiene & Tropical Medicine played a key role in the £10.6 million project, which was funded by the UK government's Department for International Development (DFID), with additional funding from USAID. It was led by Sightsavers in collaboration with 30 ministries of health who provided staff, technical support, supervision and vehicles.

The GTMP used Android technology to carry out eye examinations, and used mobile phones to record their findings on the Trachoma Atlas database. The findings of the mapping include trachoma prevalence statistics for 29 countries, including Ethiopia (a high burden country where over 50 million people are living in endemic areas), Chad, Eritrea, Pakistan, Papua New Guinea, Solomon Islands, Colombia and Yemen, with households often based in the most remote locations.

Professor David Mabey, the London School of Hygiene & Tropical Medicine's Principal Investigator on the project, said: "This project has mapped in areas where no data previously existed because of remoteness, insecurity, insufficient funding, or competing public health priorities.

"We now have a complete map of trachoma's global prevalence, which will equip health ministries in endemic countries with the information to tackle this neglected tropical disease where it is most critical, through strategies including surgery, mass distribution of antibiotics, face-cleanliness and environmental improvements such as sanitation. This project is the biggest infectious disease mapping exercise in history, and will bring us closer to the goal of global trachoma elimination by 2020."

Chief Scientist to the GTMP, Dr Anthony Solomon, an Honorary Senior Lecturer at LSHTM, and Medical Officer responsible for trachoma at WHO, said, "This project is a testament to the power of true collaboration. Working together, a network of governments, academics, non-governmental organisations and funders have been able to achieve in three years a task that would otherwise have taken 30."

Trachoma is the leading infectious cause of blindness and is responsible for 3% of the world's blindness. It is caused by the bacterium Chlamydia trachomatis, and is thought to be spread through personal contact (hands, clothing) and by flies that have been in contact with discharge from the eyes or nose of an infected person. After repeated infection it can develop into trichiasis - where the eyelids turn in and the lashes scrape the eyeball, causing great pain and often leading to permanent blindness.

Yabeiywok Sema, who is 60 years old and lives with her husband and grandchildren in Ethiopia, was diagnosed with trichiasis by the team of mappers who visited her house.  She said: "I had constant pain in my eye and could see less and less which made farming, my main source of income, difficult. I didn't visit the health clinic because I didn't realise how serious the infection was or that free surgery was available. At times the pain was very bad and I would rub my eyes to try to make it stop." Yabeiywok was referred to a local health clinic and had surgery one week later to stop her eyesight from deteriorating further.

The GTMP has also helped to strengthen public health systems by training eye health workers in trachoma diagnosis, survey methodology, analysis and data management.

The collaboration was a global partnership including Sightsavers, 30 ministries of health, the London School of Hygiene & Tropical Medicine, the International Trachoma Initiative, the World Health Organization and over 20 not-for-profit eye health organisations, most of which are members of the International Coalition for Trachoma Control. In total over 60 partners worked together across the world, representing a combined effort of an estimated 2,500 people globally.