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 to only 10 cases in 2025. Since 1986, 16 previously endemic countries have eradicated dracunculiasis, leaving the disease primarily endemic in three landlocked developing countries of central Africa Chad, Ethiopia and South Sudan. Three additional countries remain to be certified as free of dracunculiasis transmission that have had no reported human cases since the end of 2023: Angola, Mali, and Sudan. One of these, 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.
Cause
Dracunculiasis is caused by infection with the roundworm Dracunculus medinensis. D. medinensis larvae reside within small aquatic crustaceans called copepods. Humans typically get infected when they unintentionally ingest copepods while drinking water. In some cases, infected copepods are consumed by fish or frogs, which are then consumed by humans or other animals, passing along the D. medinensis larvae. During digestion the copepods die, releasing the D. medinensis larvae. The larvae exit the digestive tract by penetrating the stomach and intestine, taking refuge in the abdomen or retroperitoneal space (behind the organs near the back of the abdomen). Over the next two to three months the larvae develop into adult male and female worms. The male remains smaller at long and wide; the female is comparatively large, often over long and wide. Once the worms reach their adult size inside the human body, they mate and the male dies. Over the ensuing months, the female migrates to connective tissue or along bones, and continues to develop with her embryos.
About a year after the initial infection, the pregnant female migrates to the skin, typically in the host's lower leg or foot, forms an ulcer, and emerges. When the wound touches fresh water, the female spews a milky-white substance containing hundreds of thousands of larvae into the water. Over the next several days as the female emerges from the wound, it can continue to discharge larvae into the surrounding water. The larvae are eaten by copepods, and after two to three weeks of development, they are infectious to humans again.
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 – 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.
If an affected person submerges the wound in water, the worm spews a white substance, releasing its larvae into the water. Over the lengthy period during which the worm emerges, the open blister often becomes infected with bacteria, resulting in redness and swelling, abscesses, or, in severe cases, gangrene, sepsis, or tetanus. 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 – on average 1.8worms per person (that is, a distribution of 9worms per 5infected persons), but as many as 40 – which will emerge from separate blisters at the same time. Ninety percent of worms emerge from the legs or feet. However, worms can emerge from anywhere on the body.
Diagnosis Dracunculiasis is diagnosed by visual examination – the thin white worm emerging from the blister is unique to this disease. Dead worms sometimes calcify and can be seen in the subcutaneous tissue by X-ray. Patients usually report a history of drinking contaminated water from stagnant sources. Recent developments have enhanced the early and non-invasive identification of Dracunculus medinensis using two methods. The first method involves polymerase chain reaction (PCR) techniques, specifically the qPCR protocol, targeting the mitochondrial cytochrome b (cytb) gene of Guinea worm. The second method utilizes immunological tests, where antigen detection assays or serological tests have been developed to recognize specific markers linked to the parasite. This testing could potentially detect prepatent infections up to six months before the worms appear, making it practically significant.
Prevention
There is no vaccine for dracunculiasis, and once infected with D. medinensis there is no way to prevent the disease from running its full course. Consequently, efforts to reduce the burden of dracunculiasis focus on interrupting the reproduction cycle of D. medinensis via water supplies. A mainstay of eradication efforts is the improvement of drinking water. Nylon filters, finely woven cloth, or specialized filter straws can all remove copepods from drinking water, eliminating transmission risk. Water sources can also be treated with the larvicide compound temephos, which kills copepods, and contaminated water can be treated by boiling. Where possible, open sources of drinking water are replaced by deep wells that can serve as sources of clean water. Public education campaigns inform people in affected areas how dracunculiasis spreads and encourage those with the disease to avoid soaking their wounds in bodies of water that are used for drinking.
Treatment
There is no medicine to kill D. medinensis or prevent it from causing disease once within the body. Instead, treatment focuses on slowly and carefully removing the worm from the wound over days to weeks. Once the blister bursts and the worm begins to emerge, the wound is soaked in a bucket of water, allowing the worm to empty itself of larvae away from a source of drinking water. As the first part of the worm emerges, it is typically wrapped around a piece of gauze or a stick to maintain steady tension on the worm, encouraging its exit. Each day, several centimeters of the worm emerge from the blister, and the stick is wound to maintain tension. This is repeated daily until the full worm emerges, typically within a month. If too much tension is applied, the worm can break and die, leading to severe swelling and pain at the site of the ulcer.
Treatment for dracunculiasis also includes regular wound care to avoid infection of the open ulcer. The US Centers for Disease Control and Prevention (CDC) recommends cleaning the wound before the worm emerges. Once the worm begins to exit the body, the CDC recommends daily wound care: cleaning the wound, applying antibiotic ointment, and replacing the bandage with fresh gauze. Painkillers like aspirin or ibuprofen can help ease the pain of the worm's exit.
Outcomes Dracunculiasis is a debilitating disease, causing substantial disability in around half of those infected. People with worms emerging can be disabled for the three to ten weeks it takes the worms to fully emerge. When worms emerge near joints, inflammation or infection of the affected area can result in permanent stiffness, pain, or destruction of the joint. Some people with dracunculiasis have continuing pain for 12 to 18 months after the worm has emerged. Around 1% of dracunculiasis cases result in death from secondary infections of the wound.
When dracunculiasis was widespread, it often affected entire villages at once. Outbreaks occurring during planting and harvesting seasons severely impaired a community's agricultural operations – earning dracunculiasis the descriptor "empty granary disease" in some places. Communities affected by dracunculiasis also see reduced school attendance as children of affected parents must take over farm or household duties, and affected children may be physically prevented from walking to school for weeks.
Infection does not create immunity, so people can repeatedly experience dracunculiasis throughout their lives.
Epidemiology Dracunculiasis has become rare, with 10–15 human cases reported worldwide per year (15 in 2021, 13 in 2022, 14 in 2023, 15 in 2024, and 10 in 2025). This is down from 27 cases in 2020 and dramatically less than the estimated 3.5 million annual cases in 20 countries in 1986 – the year the World Health Assembly first called for dracunculiasis's eradication. Dracunculiasis remains endemic primarily in three countries Chad, Ethiopia and South Sudan. Three additional countries remain to be certified as free of dracunculiasis transmission that have had no reported cases since at least 2023: Angola, Mali, and Sudan. One of these, 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.