Neglected Tropical Diseases (NTDs): Accelerating Control and Elimination

Trachoma Identification Application

An estimated 1.9 million people have vision loss because of trachoma, making the need for quicker diagnosis and referral for treatment an urgent public health need. Along with researchers at the University of North Carolina at Chapel Hill, RTI created a new smartphone-based app, called Classifeye™ TT Screener, that uses machine learning to assess high-quality photos of eyelids and detect trachomatous trichiasis (TT). TT is the painful end stage of trachoma which can lead to blindness. 

We tested the app in Ethiopia and Mozambique using trained TT graders and recorders. The algorithm had more than 93% accuracy and identified 15% more true TT cases than the trained graders. With this high accuracy, TT Screener could be a powerful tool to assist health workers in identifying and referring patients for care around the world.  

Explore further: Image sequence analysis via GRU and attention for trachomatous trichiasis classification

Spatial Analysis and Modelling to Support Trachoma Elimination

Using existing data from trachoma surveillance surveys, we developed innovative spatial methods for creating trachoma risk maps that show areas of ongoing transmission prior to elimination and areas at risk of recurrence after elimination. 

This activity aimed to measure spatial clustering in the distribution of trachomatous inflammation—follicular (TF) among clusters and determine if there is a relationship between TF prevalence in clusters and available measures of local environmental and sociodemographic conditions. These findings showed how trachoma data can be used in more complex geostatistical models and have been published and shared at several international conferences.

This work has also contributed to larger discussions within the World Health Organization and global partners on the use of model-based geostatistics for estimating trachoma elimination. 

Drivers of Persistent and Recurrent Trachoma

To better understand and identify causes of persistent and recurrent active trachoma, in collaboration with the University of California San Francisco and the U.S. Centers for Disease Control and Prevention, we researched the effectiveness of alternative treatment and surveillance strategies, including adding the collection of eye swabs and dried blood samples to standard trachoma surveys. 

In Mozambique, to characterize transmission in four districts, we incorporated testing of ocular infection and serology into routine trachoma impact surveys in August 2022. We found that three recurrent districts had prevalence of trachomatous inflammation—follicular (TF) below the 5% threshold for discontinuation of antibiotic mass drug administration (MDA), while the remaining district had a TF prevalence at least 5%, confirming it as a district with persistent active trachoma. 

This was the first time globally that this type of information was incorporated into trachoma surveys and proved the feasibility of such enhanced surveys. By measuring additional biomarkers, we learned that in two of the districts with TF prevalence below 5% the observed prevalence of ocular Chlamydia trachomatis infection and seroconversion rates suggest transmission of trachoma was ongoing. Close follow-up and resumption of MDA may be required in the future. Analysis of household water and sanitation data furthered our understanding of likely drivers of ongoing trachoma transmission in this setting, including lack of access to sanitation and low sanitation coverage.

Explore further: Ongoing transmission of trachoma in low prevalence districts in Mozambique: Results from four cross-sectional enhanced impact surveys, 2022

Reaching Mobile and Migrant Populations with Health Interventions

Mobile and migrant populations (MMPs) pose a unique challenge to disease elimination campaigns as they are often hard to survey and reach with treatment. Our literature review on campaigns targeting MMPs across a selection of elimination diseases confirmed that lower service delivery to these populations results in higher disease prevalence. 

For example, one possible explanation for the persistent and recrudescent active trachoma observed in districts of northern Tanzania is that the nomadic pastoralist Maasai population is not being reached by disease control activities. To address this, the Ministry of Health and USAID’s Act to End NTDs | East program, led by RTI, have implemented more frequent than annual MDA and jointly coordinated cross-border MDA with the Kenyan Ministry of Health and Sightsavers. 

To understand the relationship between trachoma biomarkers over time and differences between areas receiving more frequent than annual and annual MDA, we are conducting a sentinel site monitoring activity including using enhanced diagnostics to measure prevalence of ocular Chlamydia trachomatis infection and serology to measure the force of infection. Also, during trachoma MDA, we piloted the use of a text message reporting system for monitoring MDA coverage in near real-time. 

Finally, thanks to an additional award from the Task Force for Global Health and in collaboration with a team in the Department of Electrical Engineering and Computer Science at the University of Missouri, we are applying artificial intelligence to recent satellite imagery to rapidly map Maasai encampments and settlements for an integrated population-based survey of NTDs and enteric and zoonotic infections.

Rapid Qualitative Approach to Improve Mass Drug Administration 

MDA is an effective way to eliminate diseases, but they often don’t reach everyone and gathering information on reasons for people not being offered or not taking the treatments is time-consuming and costly. To address this, we developed a guide that outlines a six-step process for rapid qualitative research that is easy to use at scale and within programmatic settings. 

​Explore further: Incorporating qualitative research methods into the monitoring and evaluation of neglected tropical disease programmes: A scoping literature review

Integrating Neglected Tropical Disease Activities with Other Health Programs

Combining health programs and activities can save resources, increase effectiveness, and reach more people. RTI conducted a landscape analysis on the feasibility of incorporating NTD programs into other health programs, focusing on the five NTDs treated through regular preventive chemotherapy, namely lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiasis, and trachoma.

By conducting a literature review and informant interviews, we found consensus on the attractiveness of incorporating NTDs into other health programs; however, several sources also cautioned that this approach is not appropriate in every circumstance. The challenge of incorporation is due to several factors that sometimes help and sometimes hinder it. These tensions make it difficult to develop clear guidelines for incorporation that work regardless of context.

The study also highlights the gaps in the literature, particularly the lack of formal evaluations on how programs can best incorporate into each other.  Future evaluations should focus on why incorporations succeeded or failed, rather than just whether they did.

Explore further: Incorporating NTDs into Other Health Programs

​Ongoing RTI Investment in Neglected Tropical Disease Research and Innovation

​In the coming years, we will continue to contribute to NTD research and innovation. Planned activities include: 

• Explore local impacts of and adaptations to climate change among populations and communities served by the Act to End NTDs | East program. 
• Develop innovative approaches to improve urban mass drug administration and vector control for lymphatic filariasis, building on our experience implementing malaria prevention and elimination programs.
• Determine impact of integrated vector management (IVM) on Chlamydia trachomatis transmission and Musca sorbens (eye fly) populations and determine impact of IVM on non-targeted diseases, such as scabies and strongyloidiasis. 
• Leverage our expertise in health system strengthening and reproductive, maternal & child health to identify opportunities and test approaches to integrate schistosomiasis surveillance into the maternal & child health sector.