Dracunculiasis

Other names

• Guinea worm disease, a Neglected Tropical Disease (NTD), is caused by the parasite Dracunculus medinensis.
• The disease affects poor communities in remote parts of Africa that do not have safe water to drink.
• There is neither a drug treatment for Guinea worm disease nor a vaccine to prevent it.
• Great progress has been made towards elimination of Guinea worm disease;
• The number of human cases annually has fallen from 3.5 million in the mid-1980s to 28 in 2018.

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Dracunculus medinensis

Waterborne

• GWD is spread by drinking water containing Guinea worm larvae.
• Larvae are immature forms of the worm. GWD affects poor communities in remote parts of Africa that do not have safe water to drink.
• GWD can occur at any time of the year but occurs most commonly during peak transmission season, which varies from country to country.
• In dry regions, people generally get infected during the rainy season, when stagnant surface water is available.
• In wet regions, people generally get infected during the dry season, when surface water is drying up and becoming stagnant.

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Life cycle of Dracunculus medinensis

=Rare animal infections

• GWD is primarily a human disease.
• However, in recent years infections in animals, particularly in dogs, have been reported.
• As a result of research into the cause of Guinea worm infections in animals, it is now believed that GWD might also be spread to both animals and humans by eating certain aquatic animals that might carry Guinea worm larvae, like fish or frogs, but do not themselves suffer the effects of transmission.

Neglected disease

• GWD is considered by global health officials to be a neglected tropical disease (NTD ) and it is the first parasitic disease targeted for eradication.

Causal Agent

• Dracunculiasis (guinea worm disease) is caused by the nematode (roundworm) Dracunculus medinensis.

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Dracunculus medinensis

Life Cycle

• Humans become infected by drinking unfiltered water containing copepods (small crustaceans) which are infected with larvae of D. medinensis.
• Following ingestion, the copepods die and release the larvae, which penetrate the host stomach and intestinal wall and enter the abdominal cavity and retroperitoneal space.
• After maturation into adults and copulation, the male worms die and the females (length: 70 to 120 cm) migrate in the subcutaneous tissues towards the skin surface.
• Approximately one year after infection, the female worm induces a blister on the skin, generally on the distal lower extremity, which ruptures.
• When this lesion comes into contact with water, a contact that the patient seeks to relieve the local discomfort, the female worm emerges and releases larvae.
• The larvae are ingested by a copepod and after two weeks (and two molts) have developed into infective larvae.
• Ingestion of the copepods closes the cycle

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Preventing Guinea worm disease in Chad

Symptoms

People with Guinea worm disease (GWD) have no symptoms for about 1 year. Then, the person begins to feel ill. Symptoms can include the following:

• Slight fever
• Itchy rash
• Nausea
• Vomiting
• Diarrhea
• Dizziness
• Blisters

Blisters

• The blister can form anywhere on the skin. However, the blister forms on the lower body parts in 80%–90% of cases.
• This blister gets bigger over several days and causes a burning pain.
• The blister eventually ruptures, exposing the worm.
• The infected person may put the affected body part in cool water to ease the symptoms or may enter water to perform daily tasks, such as fetching drinking water.
• On contact with water, the worm discharges hundreds of thousands of larvae into the water.

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Dracunculiasis

Complications

• In addition to the pain of the blister, removing the worm is also very painful. Furthermore, without proper care the wound often becomes infected by bacteria. These wound infections can then result in one or more of the following complications:

• Redness and swelling of the skin (cellulitis)
• Boils (abscesses)
• Generalized infection (sepsis)
• Joint infections (septic arthritis) that can cause the joints to lock and deform (contractures)
• Lock jaw (tetanus)

If the worm breaks during removal it can cause intense inflammation as the remaining part of the dead worm starts to degrade inside the body. This causes more pain, swelling, and cellulitis.

Disability

• While the death rate is low, disability is a common outcome of GWD.
• People have difficulty moving around because of pain and complications caused by secondary bacterial infections.
• The disability that occurs during worm removal and recovery prevents people from working in their fields, tending animals, going to school, and caring for their families.
• Disability lasts 8.5 weeks on average but sometimes can be permanent. When GWD was more common, the negative impacts on farming and livestock tending caused financial losses in the millions of dollars each year.
• In some villages where infection rates were high, more than 60% of children missed school.
• Some children were disabled by infection.
• Other children needed to work in place of disabled family members.

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Prevent dracunculiasis and other waterborne diseases by pasteurizing water in a solar cooker.

Poverty

• GWD only occurs in the poorest 10% of the world’s population who have no access to safe drinking water or health care.
• Therefore, GWD is both a disease of poverty and a cause of poverty

Transmission

• People become infected with Guinea worms by drinking unfiltered water from ponds and other stagnant water containing copepods (tiny “water fleas” too small to be clearly seen without a magnifying glass).
• These copepods swallow Guinea worm larvae. People who drink water containing copepods that have swallowed Guinea worm larvae can develop Guinea worm disease.

• Alternatively, it is believed that people and animals might also become infected by eating certain aquatic animals, like fish or frogs, that might have swallowed infected copepods and might carry Guinea worm larvae but do not themselves suffer the effects of infection.

• If the fish or frogs are eaten raw or undercooked, the Guinea worm larvae are then released into the human or animal digestive tract.

Reported cases of guinea worm disease, OWID

• Following ingestion, the copepods die and release the larvae, which penetrate the host stomach and intestinal wall and move to the connective tissues of the abdomen where they mate. During the next 10–14 months, the male worm dies and the pregnant female worm grows to 60–100 centimeters (2–3 feet) in length and as wide as a cooked spaghetti noodle.

• When the adult female worm is ready to release her larvae, approximately 1 year after infection, she moves to a spot just beneath the skin. A blister then forms on the skin where the worm will eventually emerge. This blister may form anywhere on the body, but usually forms on the legs and feet. This blister causes a very painful burning feeling and it bursts within 24–72 hours.

• Whether to relieve pain or as part of their daily lives (e.g., to collect water, bathe, wash clothes, cool off, etc.), people and animals infected with Guinea worm usually enter bodies of water. Water contact triggers the Guinea worm to release a milky white liquid that contains millions of immature larvae into the water. Copepods swallow these larvae and the cycle begins again.

Treatment

• There is no drug to treat Guinea worm disease and no vaccine to prevent infection.
• Once part of the worm begins to come out of the wound, the rest of the worm can only be pulled out a few centimeters each day by winding it around a piece of gauze or a small stick.
• Sometimes the whole worm can be pulled out within a few days, but the process usually takes weeks.
• Care must be taken not to break the worm during removal. If part of the worm is not removed, there is a risk for secondary bacterial infections and resulting complications.
• Anti-inflammatory medicine can help reduce pain and swelling. Antibiotic ointment can help prevent infections.

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Guinea worm case reports by year, 1989-2015.

Geographic distribution

• Only 28 cases of Guinea worm disease were reported in humans in 2018.
• These cases were reported in Angola (1 case), Chad (17 cases), and South Sudan (10 cases).
• As of February 2018, the World Health Organization had certifiedexternal iconexternal icon 199 countries, territories, and areas as being free of GWD transmission.
• Animals infected with D. medinensis, mostly domesticated dogs, have been reported since 2012.
• Most animal infections have occurred in Chad but some have been reported in Ethiopia and Mali.
• In 2018, Chad reported 1,040 infected dogs and 25 cats; Ethiopia reported 11 infected dogs, five cats, and one baboon; and Mali reported 18 infected dogs and two cats.

Risk factors

Anyone who drinks from a pond or other stagnant water source contaminated with Guinea worm larvae is at risk for infection. Larvae are immature forms of the Guinea worm. People who live in countries where GWD is occurring (such as Chad, Ethiopia, Mali, and South Sudan) and consume raw or undercooked aquatic animals (such as small whole fish that have not been gutted, other fish, and frogs) may also be at risk for GWD.

• People who live in villages where there has been a case of GWD in a human or animal in the recent past are at greatest risk.

Prevention

• Teaching people to follow these simple control measures can prevent the spread of the disease:
• Drink only water from protected sources (such as from boreholes or protected hand-dug wells) that are free from contamination.
• If this is not possible, always filter drinking water from unsafe sources using a special Guinea worm cloth filter or a Guinea worm pipe filter to remove the copepods (tiny “water fleas” too small to be clearly seen without a magnifying glass) that carry the Guinea worm larvae. Unsafe water sources include stagnant water ponds, pools in drying riverbeds, and shallow hand-dug wells without surrounding protective walls.
• Cook fish and other aquatic animals (e.g., frogs) well before eating them. Bury or burn fish entrails left over from fish processing to prevent dogs from eating them. Avoid feeding fish entrails to dogs. Avoid feeding raw or undercooked fish or aquatic animals to dogs.
• Prevent people with blisters, swellings, wounds, and visible worms emerging from their skin from entering ponds and other water sources.
• Tether dogs that have blisters, swellings, wounds, and visible worms emerging from their skin to prevent the dogs from entering ponds and other water sources.
• In addition to these health education measures, the Guinea Worm Eradication Program (GWEP) also undertakes the following two additional water-related measures to prevent GWD:
• GWEP staff treat targeted unsafe drinking water sources at risk for contamination with Guinea worm larvae with the approved chemical temephos (ABATE®*) to kill the copepods and reduce the risk of GWD transmission from that water source.
• GWEP staff provide targeted communities at risk for GWD with new safe sources of drinking water and repair broken safe water sources (e.g., hand-pumps) if possible.

Global Eradication Campaign

• The global campaign to eradicate Guinea worm disease (GWD) began in 1980 at the U.S. Centers for Disease Control and Prevention (CDC).
• CDC suggested that the eradication of GWD (also known as dracunculiasis) would be an ideal indicator of success for the United Nations International Drinking Water Supply and Sanitation Decade (IDWSSD) (1981–1990) because it was believed that people could only get GWD by drinking contaminated water.

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