Dracunculiasis, also called Guinea-worm disease (GWD), is an infection by the Guinea worm. A person becomes infected when they drink water that contains water fleas infected with guinea worm larvae.Initially there are no symptoms.About one year later, the person develops a painful burning feeling as the female worm forms a blister in the skin, usually on the lower limb.The worm then comes out of the skin over the course of a few weeks.During this time, it may be difficult to walk or work. It is very uncommon for the disease to cause death. In humans, the only known cause is Dracunculus medinensis.The worm is about one to two millimeters wide, and an adult female is 60 to 100 centimeters long (males are much shorter at 12–29 mm or 0.47–1.14 in).Outside of humans, the young form can survive up to three weeks, during which they must be eaten by water fleas to continue to develop.The larva inside water fleas may survive up to four months.Thus, in order for the disease to remain in an area, it must occur each year in humans.A diagnosis of the disease can usually be made based on the signs and symptoms of the disease. Prevention is by early diagnosis of the disease followed by keeping the person from putting the wound in drinking water to decrease spread of the parasite. Other efforts include improving access to clean water and otherwise filtering water if it is not clean.Filtering through a cloth is often enough. Contaminated drinking water may be treated with a chemical called temefos to kill the larva. There is no medication or vaccine against the disease. The worm may be slowly removed over a few weeks by rolling it over a stick. The ulcers formed by the emerging worm may get infected by bacteria. Pain may continue for months after the worm has been removed. In 2015 there were 22 reported cases of the disease and in the first half of 2016 there were 7 confirmed cases.This is down from an estimated 3.5 million cases in 1986.It only exists in 4 countries in Africa, down from 20 countries in the 1980s.It will likely be the first parasitic disease to be globally eradicated.Guinea worm disease has been known since ancient times.It is mentioned in the Egyptian medical Ebers Papyrus, dating from 1550 BC.The name dracunculiasis is derived from the Latin "affliction with little dragons", while the name "guinea worm" appeared after Europeans saw the disease on the Guinea coast of West Africa in the 17th century. Other Dracunculus species are known to infect various mammals, but do not appear to infect humans.Dracunculiasis is classified as a neglected tropical disease.Because dogs may also become infected,the eradication program is monitoring and treating dogs as well. Signs and symptoms Dracunculiasis is diagnosed by seeing the worms emerging from the lesions on the legs of infected individuals and by microscopic examinations of the larvae. As the worm moves downwards, usually to the lower leg, through the subcutaneous tissues, it leads to intense pain localized to its path of travel. The painful, burning sensation experienced by infected people has led to the disease being called "the fiery serpent". Other symptoms include fever, nausea, and vomiting. Female worms cause allergic reactions during blister formation as they migrate to the skin, causing an intense burning pain. Such allergic reactions produce rashes, nausea, diarrhea, dizziness, and localized edema. When the blister bursts, allergic reactions subside, but skin ulcers form, through which the worm can protrude. Only when the worm is removed is healing complete. Death of adult worms in joints can lead to arthritis and paralysis in the spinal cord. Cause Dracunculiasis is caused by drinking water contaminated by water fleas that host the D. medinensis larvae. Dracunculiasis has a history of being very common in some of the world's poorest areas, particularly those with limited or no access to clean water. In these areas, stagnant water sources may still host copepods, which can carry the larvae of the guinea worm. Humans and dogs are the only known animals that guinea worms infect.Other species in the Dracunculus genus affect other mammals. After ingestion, the copepods die and are digested, thus releasing the stage 3 larvae, which then penetrate the host's stomach or intestinal wall, and then enter into the abdominal cavity and retroperitoneal space. After maturation, which takes approximately three months, mating takes place; the male worm dies after mating and is absorbed by the host's body. Approximately one year after mating, the fertilized females migrate in the subcutaneous tissues adjacent to long bones or joints of the extremities. They then move towards the surface, resulting in blisters on the skin, generally on the distal lower extremity (foot). Within 72 hours, the blister ruptures, exposing one end of the emergent worm. The blister causes a very painful burning sensation as the worm emerges, and the sufferer will often immerse the affected limb in water to relieve the burning sensation. When a blister or open sore is submerged in water, the adult female releases hundreds of thousands of stage 1 guinea worm larvae, thereby contaminating the water. During the next few days, the female worm can release more larvae whenever it comes in contact with water, as it extends its posterior end through the hole in the host's skin. These larvae are eaten by copepods, and after two weeks (and two molts), the stage 3 larvae become infectious and, if not filtered from drinking water, will cause the cycle to repeat. Infected copepods can live in the water for up to 4 months. The male guinea worm is typically much smaller (12–29 mm or 0.47–1.14 in) than the female, which, as an adult, can grow to 60–100 cm (2–3 ft) long and be as thick as a spaghetti noodle. Infection does not create immunity, so people can repeatedly experience Dracunculiasis throughout their lives. In drier areas just south of the Sahara desert, cases of the disease often emerge during the rainy season, which for many agricultural communities is also the planting or harvesting season. Elsewhere, the emerging worms are more prevalent during the dry season, when ponds and lakes are smaller and copepods are thus more concentrated in them. Guinea worm disease outbreaks can cause serious disruption to local food supplies and school attendance. The infection can be acquired by eating a fish paratenic host, but this is rare. No reservoir hosts are known; that is, each generation of worms must pass through a human – or possibly a dog. Prevention Guinea worm disease can be transmitted only by drinking contaminated water, and can be completely prevented through two relatively simple measures: Prevent people from drinking contaminated water containing the Cyclops copepod (water flea), which can be seen in clear water as swimming white specks. Drink water drawn only from sources free from contamination. Filter all drinking water, using a fine-mesh cloth filter like nylon, to remove the guinea worm-containing crustaceans. Regular cotton cloth folded over a few times is an effective filter. Filter the water through ceramic or sand filters. Boil the water. Develop new sources of drinking water without the parasites, or repair dysfunctional water sources. Treat water sources with larvicides to kill the water fleas. Prevent people with emerging Guinea worms from entering water sources used for drinking. Community-level case detection and containment is key. For this, staff must go door to door looking for cases, and the population must be willing to help and not hide their cases. Immerse emerging worms in buckets of water to reduce the number of larvae in those worms, and then discard that water on dry ground. Discourage all members of the community from setting foot in the drinking water source. Guard local water sources to prevent people with emerging worms from entering. Treatment There is no vaccine or medicine to treat or prevent Guinea worm disease. Once a Guinea worm begins emerging, the first step is to do a controlled submersion of the affected area in a bucket of water. This causes the worm to discharge many of its larvae, making it less infectious. The water is then discarded on the ground far away from any water source. Submersion results in subjective relief of the burning sensation and makes subsequent extraction of the worm easier. To extract the worm, a person must wrap the live worm around a piece of gauze or a stick. The process can be long, taking anywhere from hours to a week. Gently massaging the area around the blister can help loosen the worm.This is nearly the same treatment that is noted in the famous ancient Egyptian medical text, the Ebers papyrus from 1550 BC.Some people have said that extracting a Guinea worm feels like the afflicted area is on fire.However, if the infection is identified before an ulcer forms, the worm can also be surgically removed by a trained doctor in a medical facility. Although Guinea worm disease is usually not fatal, the wound where the worm emerges could develop a secondary bacterial infection such as tetanus, which may be life-threatening—a concern in endemic areas where there is typically limited or no access to health care.Analgesics can be used to help reduce swelling and pain and antibiotic ointments can help prevent secondary infections at the wound site.At least in the Northern region of Ghana, the Guinea worm team found that antibiotic ointment on the wound site caused the wound to heal too well and too quickly making it more difficult to extract the worm and more likely that pulling would break the worm. The local team preferred to use something called "Tamale oil" (after the regional capital) which lubricated the worm and aided its extraction. It is of great importance not to break the worm when pulling it out. Broken worms have a tendency to putrefy or petrify. Putrefaction leads to the skin sloughing off around the worm. Petrification is a problem if the worm is in a joint or wrapped around a vein or other important area. Use of metronidazole or thiabendazole may make extraction easier, but also may lead to migration to other parts of the body.