Global efforts against trachoma: what have we learned from WHO’s latest report?
Last week, we saw the release of a new WHO report, showing that the number of people at risk for trachoma declined by 12 million between April 2023 and April 2024.
We sat down with Emma Harding-Esch, Chief Scientist for Tropical Data, to get her insights into the latest global trachoma data, and the role that high-quality surveys can play in speeding up our elimination of the disease.
Q1: Tell us a little about yourself and your work in trachoma elimination.
Trachoma is a disease that affects the eyes, and it’s currently the leading infectious cause of blindness around the world. I’m an epidemiologist (someone who studies patterns, causes, and control of diseases), and I have been working on trachoma for nearly 20 years.
Since 2017, I have been the Chief Scientist for Tropical Data. This is a partnership that supports health ministries worldwide to conduct standardized, high-quality surveys for trachoma, which conform to WHO recommendations.
Q2: What global progress have you witnessed since you started working in efforts to eliminate trachoma?
When I first worked on trachoma, we didn’t have a good sense of how widespread the disease was. Our estimates were often based on quite small sample sizes and from a limited number of defined populations.
This meant it was hard for governments to know where they needed to take action. Globally, it was also difficult to measure progress towards the goal of eliminating trachoma by 2020. All this changed in 2012, when the Global Trachoma Mapping Project (GTMP) started. Over 3 years, GTMP conducted baseline surveys using a standardized approach, across all accessible districts worldwide where it was suspected that trachoma was endemic.
Tropical Data builds on the success of GTMP, providing support to health ministries to assess the prevalence and impact of trachoma elimination efforts through baseline, impact, surveillance, and trachomatous trichiasis (TT)-only surveys. In 2016, when GTMP came to an end, a staggering 190.2 million people lived in districts where active trachoma was a public health problem. Today, eight years later, this has been reduced to 103.2 million people.
During this same period, there has been an increasing focus on country ownership. The 2021-2030 Road Map for Neglected Tropical Diseases (NTDs) has really helped promote this, through its shifts towards greater ownership of programs by countries; cross-cutting approaches instead of disease‑specific programs; and an increased focus on measuring impacts rather than processes.
Country ownership of the survey process and data has always been a central tenet of our work – which I think has been a key reason why countries continue to ask for our support.
Q3: What are you excited to see in the coming years of trachoma elimination efforts?
Already, 18 countries have been validated by WHO as having eliminated trachoma as a public health problem, starting with Oman in 2012. An additional 10 countries report having reduced the prevalence of trachoma below elimination thresholds. The progress made is really exciting and shows that it can be done!
I’m also excited about the innovations that are making their way into trachoma elimination programs. For instance, WHO is working on guidelines around using finger-prick blood testing, otherwise known as ‘serology’, in trachoma elimination programs. If we can detect exposure to the bacteria that causes the disease, rather than looking for evidence of the inflammatory response to infection, this will help us overcome several of the challenges we’ve encountered when examining people for active trachoma.
Inclusion of serology testing during routine trachoma surveys has proven to be feasible and is becoming increasingly important for programmatic decision-making. The Tropical Data team are now working to integrate this into our processes to ensure health ministries are able to collect this data through the standard system, if and when it is needed.
Q4: What challenges must we address in order to reach the global goals for trachoma elimination?
I think our biggest challenge is insecurity and conflict. There are still parts of the world where we suspect that trachoma is present, but we have not been able to conduct baseline surveys because it would put field teams at risk. If we are to reach the WHO’s 2030 target for trachoma, we urgently need to find ways of determining whether trachoma is a public health problem in these areas, and delivering interventions if it is.
Migratory and cross-border populations represent another challenge. There is some interesting work being done by country programs and their partners to ensure that these populations are not being left behind. For example, neighboring countries are exploring cross‑border treatment campaigns as a way of reaching these groups.
The last pockets of trachoma will be those in which disease is hardest to eliminate, and we will require bespoke strategies and a concerted international effort. We can’t take the foot off the pedal now. We should be celebrating the amazing achievements of the trachoma community, to highlight why we should continue to focus on meeting the goal of global trachoma elimination.
Q5: What role can Tropical Data play in helping us get there?
Tropical Data will continue to support health ministries to conduct high-quality surveys for trachoma.
We are also adapting our approach to meet the needs of countries. For example, we are working to incorporate innovative techniques into trachoma elimination programs, such as photo-based training for trachoma graders, and the collection of serology and infection data.
We also support health ministries to publish their survey data, so that they can share their methods, results and experiences with their peers around the world. This has been facilitated by a new partnership with the journal International Health. This knowledge-sharing provides transparency, and ensures that this data is subjected to an external peer review, before it is included in countries’ trachoma elimination dossiers that are submitted to WHO.
Tropical Data is run by a core team of partners including the International Trachoma Initiative (ITI), the London School of Hygiene & Tropical Medicine, RTI International through the USAID Act to End NTDs | East program, and Sightsavers. It is made possible thanks to the support of national programs in endemic countries, along with a range of international donors and partners.