Georgia Tech Partners with The Carter Center to Support Guinea Worm Disease Eradication

Georgia Institute of Technology (Georgia Tech) researchers have teamed up with The Carter Center to support dracunculiasis eradication efforts, using mathematical modeling and analytics. Dracunculiasis, or Guinea worm disease (GWD), is caused by the parasite Dracunculus medinensis. Currently, there is no diagnostic test to detect pre-patent infection, no vaccine, and no treatment for GWD. Eradication efforts focus on community-based surveillance, health education, targeted treatment of water sources with larvicide, and most importantly, behavioral changes, such as filtering drinking water and preventing humans and animals, mainly domesticated dogs with emerging worms, from entering and contaminating water sources.  “Given the year-long life-cycle of the disease, mathematical modeling is a valuable tool for fine-tuning interventions and evaluating resource allocation decisions,” said Pinar Keskinocak, professor in the School of Industrial and Systems Engineering (ISyE) and the director of the Center for Health and Humanitarian Systems.

Disease Dynamics

Dracunculus medinensis is a parasite that infects in a vicious cycle. When a human or animal host  ingests either water contaminated with infective Guinea worm larvae or raw or undercooked aquatic animals that harbor the infectious larvae, the larvae mate in the host’s body, and, after 10-14 months, a pregnant female worm that can be as long as one meter emerges slowly and painfully from the host’s body. To seek relief, the host might immerse the affected body part into a water source (e.g., a pond), releasing the worm’s larvae into the water source, contaminating it, and continuing the infection cycle. In particular, worms emerging from dogs can contaminate drinking water sources used by people and in turn, lead to infection of people or other dogs in the community. 

Progress Toward GWD Eradication

GWD eradication efforts worldwide have been supported by the collaboration of many entities, including The Carter Center, ministries of health in endemic countries, WHO, CDC, UNICEF, and others. Since 1986, The Carter Center has led the international Guinea worm eradication campaign, which has eliminated the ancient disease in 16 countries in Africa and Asia. In 2022, Guinea worm was reported in five African countries.

Together with The Carter Center and Chad’s national Guinea Worm Eradication Program, Georgia Tech researchers have developed an agent-based simulation model that incorporates the life-cycle of the worm, daily interactions between dogs and water sources, seasonality of infections, and environmental factors such as rainfall and temperature. The models can also capture the influence of dog movement between multiple regions/water sources. Using these mathematical models in a wide range of simulated scenarios, the researchers evaluated the impact of combinations of interventions (such as water treatment or tethering of dogs). The results from the simulated scenarios suggest that historical levels of interventions in Chad, even when adjusted to regional differences, might not be sufficient to interrupt GWD transmission in dogs within the next five years. Hence, there is a need to improve intervention implementation fidelity, adjust implementation approaches, or implement new interventions.

GWD Eradication Onward

New interventions, such as a diagnostic test that can detect pre-patent infection, could help accelerate the progress toward eradication.  To guide research and development of such a test, WHO initiated the development of target product profiles (TPPs), outlining preferred and minimally acceptable criteria for novel diagnostic tests, which could be, according to WHO, “a game changer in speeding up a global eradiation of the parasite.”

Georgia Tech researchers adapted an agent-based simulation model and evaluated a wide range of scenarios to assess the impact of a new diagnostic test to detect pre-patent infection in dogs on the disease spread. In the mathematical model, each dog is represented by an "agent," which mimics the dog behavior, their interactions with the water source, and the progression of the disease within a dog.

In the absence of a treatment for GWD, the research results quantify the impact of the diagnostic accuracy (sensitivity and specificity) of the test, but also emphasize the importance of rollout decisions and the compliance of dog owners with the recommended tethering practices. “The potential benefits of testing depend on test accuracy, but also on several other factors, e.g., how the test is deployed, and how it affects owners’ behaviors regarding tethering of dogs with positive or negative test results,” said Hannah Smalley, a research engineer in ISyE. “For example, even if the test could detect pre-patent infections in dogs with perfect accuracy, if dogs are not tested frequently enough, or if owners do not consistently tether test-positive dogs, then the impact of such a diagnostic test could be limited.” The timing of when, i.e., how far in advance of worm emergence, the test can detect pre-patent infection is also important. For example, if the test could not only detect pre-patent infection but also accurately estimate the timing of worm emergence, this could increase the owners’ compliance with tethering recommendations during the time period leading to estimated worm emergence, reduce the need for long-term tethering, and reduce the resources (human and financial) needed to support the intervention.

Recommendations from the research are included in the WHO’s TPP for a diagnostic test to detect pre-patent Guinea worm infections in animals. “This important research highlights how a novel diagnostic test that can detect pre-patent Guinea worm infections could help, especially if used in conjunction with existing interventions,” said Adam Weiss [Director of The Carter Center’s Guinea Worm Eradication Program], “and we are looking forward to continuing our collaborations with Georgia Tech as a means to support GWD eradication efforts.”