Dracunculiasis

Dracunculiasis, also called Guinea-worm disease, is a parasitic infection by the Guinea worm (Dracunculus medinensis). A person becomes infected by drinking water contaminated with Guinea-worm larvae that reside inside copepods (a type of small crustacean). Stomach acid digests the copepod and releases the Guinea worm larva, which penetrates the digestive tract and escapes into the body. Around a year later, the adult female worm migrates to an exit site – usually the lower leg – and induces an intensely painful blister on the skin. Eventually, the blister bursts, creating a painful wound from which the worm gradually emerges over several weeks. The wound remains painful throughout the worm's emergence, disabling the affected person for the three to ten weeks it takes the worm to emerge. The female worm releases larvae when the host submerges the wound in water in attempts to relieve the pain, thus continuing the life cycle.

There is no medication to treat or prevent dracunculiasis. Instead, the mainstay of treatment is the careful wrapping of the emerging worm around a small stick or gauze to encourage and speed up its exit. Each day, a few more centimeters of the worm emerge, and the stick is turned to maintain gentle tension. Too much tension can break and kill the worm in the wound, causing severe pain and swelling. Dracunculiasis is a disease of extreme poverty, occurring in places with poor access to clean drinking water. Prevention efforts center on filtering drinking water to remove copepods as well as public education campaigns to discourage people from soaking affected limbs in sources of drinking water, as this action allows the worms to spread their larvae.

Accounts consistent with dracunculiasis appear in surviving documents from physicians of Greco-Roman antiquity. In the 19th and early 20th centuries, dracunculiasis was widespread across much of Africa and South Asia, affecting as many as 48 million people per year. The effort to eradicate dracunculiasis began in the 1980s following the successful eradication of smallpox in 1977. By 1995, nearly every country with endemic dracunculiasis had established a national eradication program. In the ensuing years, dracunculiasis cases have dropped precipitously, falling below 100,000 cases per year in 1997, below 10,000 cases in 2007, below 1,000 cases in 2012, below 100 cases in 2015, and reaching down to 13–15 cases per year for 2021–2024. Since 1986, 16 previously endemic countries have eradicated dracunculiasis, leaving the disease primarily endemic in two landlocked developing countries of central Africa that have experienced recent political instability – Chad and South Sudan. Four additional countries remain to be certified as free of dracunculiasis transmission that have had no reported human cases since the end of 2023: Angola, Ethiopia, Mali, and Sudan. One of these four, Sudan, is pre-certified but not yet confirmed free of transmissions. Additionally, although Cameroon has been certified free of internal transmission since 2007, it has experienced three cases since 2019 along its border with Chad. D. medinensis can also infect dogs, cats, and baboons, though non-human cases are also falling due to the eradication efforts. Other Dracunculus species cause dracunculiasis in reptiles worldwide and in mammals in the Americas.

In 2020, the World Health Organization set 2027 as its target date for eradication of dracunculiasis. If the eradication program succeeds, dracunculiasis is expected to become the second human disease to be eradicated, after smallpox.