Dracunculiasis, also called Guinea-worm disease, is a parasitic infection by the Guinea worm, Dracunculus medinensis. A person typically becomes infected by drinking water containing water fleas infected with guinea worm larvae. The larvae penetrate the digestive tract and escape into the body where the females and males mate. Around a year later, the adult female migrates to an exit site – usually a lower limb – and induces an intensely painful blister on the skin. The blister eventually bursts to form an intensely painful wound, out of which the worm slowly crawls over several weeks. The wound remains painful throughout the worm's emergence, disabling the infected person for the three to ten weeks it takes the worm to emerge. During this time, the open wound can become infected with bacteria, leading to death in around 1% of cases.
There is no known antihelminthic agent to expel the Guinea worm. Instead, the mainstay of treatment is the careful wrapping of the emerging worm around a small stick or gauze to encourage 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 at the ulcer site. 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 water fleas, as well as public education campaigns to discourage people from soaking their emerging worms in sources of drinking water.
Humans have had dracunculiasis since at least 1,000 BCE, and accounts consistent with dracunculiasis appear in surviving documents from physicians of 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. By 1995, every country with endemic dracunculiasis had established a national eradication program. In the ensuing years, dracunculiasis cases have dropped precipitously, with only a few dozen annual cases worldwide since 2015. Fifteen previously endemic countries have been certified to have eradicated dracunculiasis, leaving the disease endemic in just four countries: Chad, Ethiopia, Mali, and South Sudan. A record low 13 cases of dracunculiasis were reported worldwide in 2022. If the eradication program succeeds, dracunculiasis will become the second human disease known to have been eradicated, after smallpox.
Signs and symptoms
The first signs of dracunculiasis occur around a year after infection, as the full-grown female worm prepares to leave the infected person's body. As the worm migrates to its exit site – typically the lower leg, though they can emerge anywhere on the body – some people have allergic reactions, including hives, fever, dizziness, nausea, vomiting, and diarrhea. Upon reaching its destination, the worm forms a fluid-filled blister under the skin. Over 1–3 days, the blister grows larger, begins to cause severe burning pain, and eventually bursts leaving a small open wound. The wound remains intensely painful as the worm slowly emerges over several weeks to months.
In an attempt to alleviate the excruciating burning pain, the host will nearly always attempt to submerge the affected body part in water. When the worm is exposed to water, it spews a white substance containing thousands of larvae. As the worm emerges, the open blister often becomes infected with bacteria, resulting in redness and swelling, the formation of abscesses, or in severe cases gangrene, sepsis or lockjaw. When the secondary infection is near a joint (typically the ankle), the damage to the joint can result in stiffness, arthritis, or contractures.
Infected people commonly harbor multiple worms – with an average 1.8 worms per person; up to 40 at a time – which will emerge from separate blisters at the same time. 90% of worms emerge from the legs or feet. However, worms can emerge from anywhere on the body.