How Long is the Last Mile? The Path to Guinea Worm Elimination in Chad: A Simulation Modeling Study

Guinea worm disease (GWD) is on track to be the first parasitic infectious disease to be eradicated. Substantial progress has been made, from 3.5 million human cases reported annually in the 1980s to only 10 in 2025. However, 684 animal infections were reported in 2025, the majority of which were in dogs. While animal infections continue, the human population remains at risk; elimination requires interrupting infections in both humans and animals. In the present study, agent-based simulation modeling was used to evaluate the time to elimination of GWD among domestic dogs in Chad. Infections were projected over 20 years in a variety of scenarios that accounted for current interventions, namely reactive and proactive tethering, Abate® water treatments, and novel domestic dog diagnostics. Simulation results indicated that high levels of interventions were needed to achieve the elimination of GWD in dogs in Chad; they suggested that elimination could be achieved in 7 years (95% empirical interval: 3-10 years) with "high" levels of proactive tethering and 90% Abate impact, whereas lower levels of these interventions extended the time to elimination beyond 20 years. Importantly, tools such as novel dog diagnostics (under development) could accelerate progress when paired with frequent testing and sustained tethering of dogs that have tested positive. Although challenges remain, intensified application of proven strategies combined with innovative tools offers a path to eliminating GWD in dogs and ultimately achieving global eradication.