Dracunculiasis

Dracunculiasis, also called Guinea-worm disease (GWD), is a parasitic 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 female worm forms a painful blister in the skin, usually on a lower limb. Other symptoms at this time may include vomiting and dizziness. The worm then emerges from 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. Dracunculiasis, also called Guinea-worm disease (GWD), is a parasitic 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 female worm forms a painful blister in the skin, usually on a lower limb. Other symptoms at this time may include vomiting and dizziness. The worm then emerges from 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 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, 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. 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 to remove the water fleas. 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 while in 2017 there were 30. This is down from an estimated 3.5 million cases in 1986. In 2016 the disease occurred in three countries, all 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. The method of removing the worm is described 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. 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 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. The pain caused by the worm's emergence—which typically occurs during planting and harvesting seasons—prevents many people from working or attending school for as long as three months. In heavily burdened agricultural villages fewer people are able to tend their fields or livestock, resulting in food shortages and lower earnings. A study in southeastern Nigeria, for example, found that rice farmers in a small area lost US$20 million in just one year due to outbreaks of Guinea worm disease. Dracunculiasis is caused by drinking water contaminated by water fleas that host the Dracunculiasis 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. 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.