Elimination of Trachoma—Knowing Where to Intervene

Trachoma, a chronic conjunctivitis caused by Chlamydia trachomatis, remains the leading cause of infectious blindness in the world. The World Health Organization (WHO) has classified trachoma as one of the neglected tropical diseases (NTDs) that is targeted for elimination as a public health problem. Five years ago, trachoma was still one of the more neglected of the NTDs, but increased attention and funding from major donors, like the Department for International Development (DFID) and the United States Agency for International Development (USAID), combined with continued commitment from Pfizer for the donation of Zithromax has put trachoma on track for elimination.

In 2011, the publication of 2020 INSight¹ provided a roadmap for the elimination of trachoma as a public health problem. In this document one of the main barriers identified was the lack of knowing where to intervene; this document called for completing the mapping of trachoma in all suspected endemic districts and thus, to provide evidence on where to intervene and where not to.

At the same time, during the strategic planning for the International Trachoma Initiative (ITI), its Trachoma Expert Committee agreed that mapping of trachoma should be a main priority for ITI and be part of its strategic funding. ITI brought together experts in the field to plan this exercise and negotiations were initiated with DFID to finalize the trachoma map; this led to a collaboration between ITI, Sightsavers, and the London School for Hygiene and Tropical Medicine for the Global Trachoma Mapping Project (GTMP).

In order for this exercise to be successful, it was important to ensure that the entire trachoma community supported and “owned” the work; the preliminary work by ITI was therefore designed to be inclusive with as many partners as possible. This led to the establishment of a steering committee overseeing several working groups, each addressing specific areas of work. Having these elements in place enabled GTMP to hit the road running.

In the 3 years of the GTMP, the project surveyed 1541 districts in 29 countries, examining over 2.6 million persons.² There are six articles in this issue that are an outcome of the GTMP, and additional articles are anticipated in a forthcoming supplementary issue of Ophthalmic Epidemiology. As readers will note in the funding/acknowledgment section of all of these articles, this incredible exercise was only possible due to the collaboration and dedication of countries, partners, and individual academics involved as well as committed donors like DFID and USAID. Collaborative research of this scale is rare and should be lauded in an increasingly connected research landscape.

Although the GTMP has helped the global community to better understand the burden of trachoma and where to intervene or not, some areas still remain un-surveyed due to insecurity, or the project timeline. The lessons learned, as noted in the article by Heggen and colleagues in this issue,³ and the systems developed through the GTMP, have been expanded and secured in a new project: Tropical Data, which allows these new surveys to use the tremendous experience gained during this unprecedented disease mapping exercise. Expect to see additional advances in how we assess trachoma, how we conduct surveys, and how we confidently reach our elimination targets.

Many questions remain unanswered, as other articles in this special issue attest to. The methods of the ASANTE trial are in this issue;⁴ it is likely that findings from this study will provide information for program decisions in the coming years. Surveys undertaken in Brazil (prior to GTMP), as reported in this issue, sought to determine if further trachoma control efforts were indicated or not, and it appears that trachoma is only focally distributed in the country.^5,6

Readers interested in the evolution of trachoma globally will be able to find much information in this issue and the upcoming supplement of Ophthalmic Epidemiology. Trachoma elimination is no longer aspirational; it is attainable.