World’s largest infectious disease surveys reach 50th country

The largest surveys ever undertaken for an infectious disease reach an important milestone this summer. Sierra Leone has become the 50th country to be surveyed for trachoma, a painful and potentially blinding but preventable neglected tropical disease. The series of surveys began as the Global Trachoma Mapping Project, later becoming the Tropical Data collaboration.

Health workers have been going door-to-door since 2012, often in remote and difficult environments, checking people’s eyes for trachoma and recording the results straight into their smart phones. This makes sure health ministry staff can access the fast, reliable data they need in the fight to treat and eliminate the disease.

Almost 10 million people have had their eyes checked for trachoma since the series of surveys started in 2012. Even with the disruption of COVID-19, on average one person has been examined for trachoma every 26 seconds.

The evidence the surveys provide is vital in the fight to eliminate the disease – helping governments and health workers find people who still need treatment even if they live in very remote areas. Since it began Tropical Data has showed that mass drug administration should be started or continued in more than 580 districts, could be stopped in more than 650 districts and that elimination has been achieved in more than 450 districts across the countries surveyed.

137 million people around the world remain at risk from trachoma. The work in Sierra Leone highlights both the challenges and importance of the surveys. Some of the final regions being looked at are on the border with Guinea where Tropical Data has also carried out surveys and where trachoma is a public health problem. Diseases don’t respect international borders and people moving between countries makes them some the hardest places to monitor and treat diseases. It’s the health workers’ responsibility to find and check everyone so that no-one is left behind.

The Tropical Data collaboration has run since 2016 and built on the Global Trachoma Mapping Project which ran between 2012 and 2016. It is a collaboration between Sightsavers, the International Trachoma Initiative, the London School of Hygiene & Tropical Medicine, RTI International with support from the U.S. Agency for International Development (USAID) Act to End Neglected Tropical Diseases East program and the World Health Organization.