Guinea-worm disease (GWD) is a neglected tropical disease (NTD) caused by the parasitic worm Dracunculus medinensis. In 1988, the Carter Center launched the campaign to eradicate the disease. The global campaign has been very successful, bringing the world-wide number of GWD cases down from 3.5 million in 1986 to low double digits in 2015 and thereafter. However, GWD now shows a peculiar pattern and is resurfacing again: not in humans, but mostly in dogs and other animals. Moreover, despite the fact that mathematical modeling is a standard and indispensable tool for NTDs elimination efforts, there are fewer than ten models of GWD. In this paper, we review most of those models and illustrate their basic assumptions and modeling techniques. We demonstrate that as the understanding of the Guinea worm biology evolved, so did the mathematical models. We also point out to what is still missing in all of these GWD models and discuss potential future research directions.
Guinea-worm disease (GWD) is caused by the parasitic worm Dracunculus medinensis. The disease used to affect primarily poor communities in remote rural areas without adequate access to safe water [Muller 1979]. It has been known and recognized since antiquity, mostly due to the impressive size of the parasite, up to 800 mm–1200 mm in length, and its unusual mode of life [Muller 1971].
The complex life cycle, as known by the early 2000s, is shown in Figure 1. In humans, the mature female worm migrates to the lower extremities and creates a painful blister. The pain causes the host to immerse the blister in the water, typically a source of drinking water for the whole community. Once in water, the worm releases millions of larvae into it. The free larvae are eaten by copepods (tiny crustaceans) or by water fleas. Inside the copepods, the larvae undergo two molt stages. If, at that point, the infected copepods are swallowed by humans, the larvae can then grow into maturity, mate, and the cycle continues.