Neglected tropical diseases

Blinding trachoma: smartphones spur mapping of infectious disease

More than 1.7 million people in 19 countries examined in two years
25 July 2014 | Geneva
©Dominic Nahr/Magnum/Sightsavers, 2013
Health worker using a smartphone to transmit trachoma survey data in Oromia Region, Ethiopia. Survey teams also capture data on availability of water, sanitation and hygiene facilities for each household.

An ambitious project to map the prevalence of trachoma – the most important infectious cause of blindness – has nearly completed its initial scope of work within a span of 2 years with the help of smartphone technology.

The Global Trachoma Mapping Project, funded by the United Kingdom’s Department for International Development, was launched by Sightsavers, the London School of Hygiene & Tropical Medicine and the International Trachoma Initiative in 2012 and is scheduled for completion in March 2015. Already 94% of identified districts have been surveyed – 9 months ahead of schedule.

"This is an amazing achievement and the progress so far brings the goal of global trachoma elimination by 2020 a few steps closer to becoming a reality," says Dr Anthony Solomon, Medical Officer at WHO’s Department of Control of Neglected Tropical Diseases in Geneva. “We thank the hundreds of incredibly hard working teams and supervisors who have contributed to the project in the searing heat, sand storms, appalling roads and torrential rains of some of the most difficult-to-reach communities in the world.

The project uses a standardized assessment survey carried out by trained eye health workers, who visit and examine people living in a sample of communities within pre-identified districts and transmit data on the presence of the disease through smartphones.

To date, the mapping project has:

  • examined more than 1.7 million people across 19 countries, representing one patient every 30 seconds;
  • mapped 1162 districts, containing a total population of 137 million people;
  • processed more than 28 million data items through smartphones, involving more than 700 trained field workers.

The data captured are being used to update and support country-specific trachoma programmes in line with the WHO-recommended SAFE Strategy1 and to plan the delivery and distribution of donated medicines to remote areas, help health workers plan eye surgeries and improve access to safe water, sanitation and hygiene.

As a result of the project’s success and its completion ahead of time, an additional 550 districts will be added to its scope between now and March 2015. In some countries, such as Nigeria, the project has also worked with the Ministry of Health and other partners to collect data on the prevalence of other neglected tropical diseases such as lymphatic filariasis, schistosomiasis and soil-transmitted helminthiases.

The disease

Blinding 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 endemic areas and are at risk of infection.

The disease is caused by an intracellular micro-organism (Chlamydia trachomatis) transmitted through contact with ocular and nasal discharge of infected people, particularly young children who form the reservoir of infection. It is also spread by flies that have been in contact with the eyes and nose of infected people.

In areas where trachoma is endemic, active trachoma is common among preschool-aged children, with prevalence rates as high as 60–90%.

Infection becomes less frequent and shorter in duration with increasing age. It is usually acquired through living in close proximity to a person with active disease, and the family is the principal unit for transmission.

1The SAFE strategy comprises Surgery for individuals with trichiasis; Antibiotics to reduce the reservoir of ocular chlamydial infection; and Facial cleanliness and Environmental improvement to reduce transmission.