As the world focused on COVID-19, a silent crisis was unfolding in the shadows of global health priorities
Imagine a group of diseases so devastating that they affect over 1 billion people worldwide, yet so overlooked that they're called "neglected" tropical diseases. As the world focused on COVID-19, a silent crisis was unfolding in the shadows. Neglected tropical diseases (NTDs), a group of 21 infectious conditions, found new opportunities to spread while global attention was elsewhere.
NTDs are a diverse group of infectious diseases that disproportionately affect the world's most vulnerable populations, causing severe pain, permanent disability, and social stigma.
This article explores how the coronavirus pandemic disrupted NTD control programs, the consequences of these disruptions, and the scientific innovations emerging in response to this growing health threat.
NTDs are a diverse group of infectious diseases caused by pathogens including parasites, bacteria, viruses, and fungi. What unites them is their predilection for the world's most vulnerable populations—those living in poverty, without adequate sanitation, and with limited access to healthcare.
Different NTDs identified by WHO
People affected worldwide
Countries eliminated at least one NTD pre-COVID
When COVID-19 emerged, it triggered a chain reaction of disruptions to NTD programs:
Health workers normally dedicated to NTD programs were reassigned to COVID-19 response teams, and manufacturing of diagnostic tests for NTDs was often shifted to produce COVID-19 tests instead 6 .
Production and distribution of essential medicines were disrupted, leading to critical shortages. In Africa alone, over 55 million NTD tablets risked expiration by the end of 2025 1 .
Limited disease surveillance capabilities meant that NTD outbreaks went undetected, allowing for unchecked transmission in vulnerable communities.
| Type of Disruption | Impact on NTD Programs | Population Affected |
|---|---|---|
| Suspended mass drug administration | Delayed 47 treatment campaigns | 143 million people |
| Health worker reassignment | Reduced program implementation capacity | Across 26+ countries |
| Diagnostic manufacturing shifts | Limited disease surveillance | Uncertain number |
| Medicine supply chain issues | 55 million tablets at risk of expiration | Primarily African nations |
When the pandemic disrupted NTD programs, scientists faced a critical question: what would be the long-term impact of these interruptions? A comprehensive mathematical modeling study published in The Lancet Global Health in 2022 provided crucial answers 5 .
The research team used seven well-established mathematical models to simulate the impact of COVID-19 disruptions on different NTDs. Each model incorporated:
The findings revealed that even short disruptions could have long-lasting consequences:
For diseases like schistosomiasis, onchocerciasis, trachoma, and visceral leishmaniasis, a one-year interruption could result in an average 2-3 year delay in reaching elimination targets, particularly in high-prevalence areas 5 .
The impact wasn't uniform—diseases with faster transmission rates bounced back more quickly, and areas with higher pre-control prevalence were more vulnerable to setbacks.
Perhaps most importantly, the research demonstrated that these delays could be significantly reduced through mitigation strategies such as additional mass drug administration rounds or enhanced case-finding when programs resumed.
Average delay in elimination targets for multiple NTDs due to 1-year program interruption
| Neglected Tropical Disease | Mean Delay to Elimination Targets | Most Affected Settings |
|---|---|---|
| Schistosomiasis | 2-3 years | High prevalence areas |
| Onchocerciasis | 2-3 years | High transmission areas |
| Trachoma | 2-3 years | High prevalence areas |
| Visceral Leishmaniasis | 2-3 years | High incidence areas |
| Lymphatic Filariasis | ~1 year | All endemic areas |
| Soil-transmitted Helminths | <1 year | All endemic areas |
Research on NTDs relies on specialized reagents and tools. Here are some key components of the NTD research toolkit:
| Research Tool | Primary Function | Application Examples |
|---|---|---|
| Omics technologies (genomics, transcriptomics, proteomics) | Disease mechanism understanding | Identifying drug targets in Opisthorchis viverrini liver fluke infections 4 |
| Mathematical transmission models | Predicting intervention impact | Evaluating effect of program interruptions during COVID-19 5 |
| Rapid diagnostic tests (RDTs) | Disease detection and surveillance | Identifying NTD cases in remote communities 6 |
| Molecular diagnostic assays | Pathogen identification | Detecting dengue, chikungunya in acute febrile illness 3 |
| Artificial Intelligence algorithms | Data analysis acceleration | Analyzing genomic data for potential drug targets 4 |
| Mass drug administration (MDA) platforms | Treatment distribution | Community-wide preventive chemotherapy |
Understanding pathogen biology and identifying drug targets
Rapid tests for disease detection in resource-limited settings
Mass drug administration for community-wide prevention
The COVID-19 pandemic prompted NTD programs to develop innovative strategies to overcome unprecedented challenges.
In many regions, the pandemic revealed opportunities to strengthen health systems:
Some NTD programs partnered with other essential health services that continued operating during lockdowns, allowing limited NTD activities to continue .
As the pandemic eroded trust in health systems, NTD programs placed greater emphasis on community engagement to rebuild relationships and encourage participation in treatment programs .
Programs increasingly used mobile health technologies and digital tools for surveillance, communication, and monitoring 6 .
Research identified several effective approaches to regain lost ground:
Implementing extra mass drug administration campaigns can help programs "catch up" after interruptions 8 .
Increasing the reach of existing interventions, such as extending treatment to adults in typically school-based programs for soil-transmitted helminths 5 .
For some diseases like onchocerciasis, switching to biannual rather than annual treatment proved more effective for mitigation 8 .
Research shows that targeted interventions can significantly reduce the setbacks caused by pandemic disruptions:
Additional MDA Rounds 85% effective
Enhanced Coverage 78% effective
Adapted Schedules 72% effective
In several African countries, community health workers played a crucial role in maintaining NTD services during lockdowns by conducting door-to-door drug distribution and surveillance.
Despite the challenges, significant scientific progress continues in developing new tools to combat NTDs.
Researchers are screening plant-derived compounds for activity against NTDs. Compounds from V. cinerea plants, including β-amyrin and luteolin, show promise against Dengue virus 4 .
Studies evaluated modified coptisine derivatives as potential treatments for multiple pathogens, including Rhizomucor miehei (fungus) and Marburg virus 3 .
For bovine babesiosis, research demonstrated that buparvaquone was more effective than imidocarb dipropionate, informing treatment choices 4 .
For chikungunya virus, a vaccine candidate using pre-membrane and envelope glycoproteins has shown over 90% effectiveness in Phase I clinical trials 4 .
Phase I Trial Success
Two vaccines—Dengvaxia® and Qdenga®—are already licensed for human use, representing significant progress against this widespread mosquito-borne disease 4 .
Omics technologies and computational tools are accelerating vaccine development for parasitic infections like Opisthorchis viverrini, which can cause liver damage and cancer 4 .
Computational Tools
Omics Data
AI Algorithms
Vaccine Design
The COVID-19 pandemic created unprecedented challenges for NTD control, potentially setting back elimination efforts by years. Yet, this crisis has also revealed opportunities to build more resilient, integrated health systems and accelerate innovation in disease control.
As the world continues to navigate the aftermath of COVID-19, sustained commitment to NTD control—backed by scientific innovation, adequate funding, and global cooperation—remains essential to achieve the goal of eliminating these devastating diseases by 2030.
In our interconnected world, health security cannot be achieved by fighting just one disease at a time. A comprehensive approach that addresses all health threats, including neglected tropical diseases, is essential for protecting vulnerable communities and maintaining global health progress.