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The program has made great strides from 3.5 million cases annually in the mid-1980s to 28 human cases in 2018. Global eradication is within reach.

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.

Above Images: Left: Woman gathering water in a pond. Guinea worm disease is transmitted by drinking unfiltered water from ponds and other stagnant surface water sources. Center: A health worker providing education to children about how to avoid getting Guinea worm disease. Right: A young man using a pipe filter to drink from a pond. Pipe filters help remove the water fleas that carry Dracunculus medinensis. Credit: CDC PHIL, The Carter Center

Causal Agent:

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

Today, GWD affects poor communities in remote parts of Africa that do not have safe water to drink. People become infected with Guinea worm by drinking stagnant water containing copepods (tiny “water fleas” too small to be clearly seen without a magnifying glass) that carry Guinea worm larvae (immature forms of the worm). The larvae are swallowed by the copepods that live in these stagnant water sources. The larvae need about 2 weeks to mature inside the copepods before they can infect humans. Unsafe stagnant water includes ponds, pools in drying riverbeds, and shallow hand-dug wells without surrounding protective walls. Anyone who drinks from contaminated water sources can become infected. GWD is not normally caught from drinking flowing water (rivers and streams) . Alternatively, persons 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) might also be at risk for GWD .

GWD transmission has a seasonal pattern. 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 .

The risk for disease varies by sex, age, profession, and ethnicity. These differences reflect how and where people get their drinking water in different areas and countries. In general, about the same number of men and women get infected. GWD occurs in all age groups but it is most common among young adults 15–45 years old. This may be because of the type of work done by people this age. Farmers, herders, and those fetching drinking water for the household may be more likely to become infected, possibly because they drink contaminated stagnant water while away from home. In certain areas, GWD affects some ethnic groups more than others .

The greatest risk for GWD is having GWD the year before. People do not become immune to infection. Many people in affected villages suffer from GWD year after year. This is probably because the same water sources are repeatedly contaminated and conditions that support the spread of disease have not changed. It might also be related to some biological characteristic of the person that increases susceptibility. Not everyone drinking from the same contaminated water supply will become infected. A few people seem to keep getting infected while others drinking the same water do not .

Since 2012, an unusual epidemiologic pattern has been recognized in Chad. While the number of cases in humans has remained limited, there have been large numbers of cases recognized in dogs, particularly in the area along the Chari River. This has led to consideration of the possibility of GWD transmission though a previously unrecognized route—consumption of fish, frogs, or other aquatic animals that carry Guinea worm larvae, but do not themselves suffer the effects of transmission . The situation is being carefully investigated and control measures (tethering of dogs, education to remind area residents to fully cook food and not feed fish guts to dogs) have been implemented

While most Guinea worm infections in animals have occurred in dogs and most dog infections have occurred in Chad, dog infections have occurred in other countries as well and Guinea worms have infected other types of animals too. In 2018, Chad reported 1,040 Guinea worm-infected dogs and 25 cats; Ethiopia reported 11 infected dogs, five cats, and one baboon; and Mali reported 18 infected dogs and two cats.

Symptoms

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

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

A blister then develops. This 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.

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.

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.

When the Guinea worm is ready to come out of the body, it creates a painful burning blister on the skin. The blister eventually ruptures, exposing the worm. Management of Guinea worm disease (GWD) involves removing the whole worm and caring for the wound in general. There is no specific drug to treat or prevent GWD. There is also no vaccine to prevent GWD.

Optimal management of GWD involves the following steps:

1. First, the infected person is not allowed to enter drinking water sources.
2. Next, the wound is cleaned. The affected body part may be immersed or soaked in water (far away from any water source to prevent contamination) to encourage the worm to contract and release larvae. Emptying the worm of larvae may make removing the worm easier.
3. The worm is then wrapped around a rolled piece of gauze or a stick to maintain some tension on the worm and encourage more of the worm to emerge. This also prevents the worm from slipping back inside.
4. Then, gentle traction is applied to the worm to slowly pull it out. Pulling stops when resistance is met to avoid breaking the worm. Because the worm can be as long as one meter in length, full extraction can take several days to weeks.
5. Afterwards, topical antibiotics are applied to the wound to prevent secondary bacterial infections.
6. The affected body part is then bandaged with fresh gauze to protect the site. Medicines, such as aspirin or ibuprofen, are given to help ease the pain of this process and reduce inflammation.
7. These steps are repeated every day until the whole worm is successfully pulled out.

Guinea Worm Eradication Program Interventions

The Guinea Worm Eradication Program (GWEP) includes a group of national and international partners whose purpose is to support the global eradication of Guinea worm disease (GWD). Prevention of GWD is based on the following:

• Surveillance (case detection) and case containment (preventing contamination of drinking water sources by infected persons or animals)
• Provision of safe drinking water
• Vector control (killing of the copepods involved in the Guinea worm life cycle) using the approved chemical temephos
• Health education and community mobilization.

Many of these interventions are provided by village volunteers—people who are selected by the community to work with the GWEP. Village volunteers are the backbone of the program. In their communities, they identify and manage people with GWD and prevent them from contaminating drinking water sources (case containment). They also distribute water filters and provide health education to the community.

Surveillance and Case Containment

GWEP village volunteers look daily for GWD cases in their communities. Every month they report the total number of cases detected in their communities to supervisors who compile this and send it to the national GWEP headquarters. This information is then shared with The Carter Center and the World Health Organization (WHO). The GWEP uses this information to identify where transmission is ongoing and to understand how the disease is spreading.

Case containment is one of the key methods used to prevent the spread of GWD. Case containment centers have been built in strategic locations in several countries. These centers provide treatment and support to people with GWD and help prevent them from contaminating water sources. A case of GWD is considered to be contained when

1. The person is identified within 24 hours of the worm emerging; AND
2. The person has not entered any water source since the worm has emerged; AND
3. The person receives proper treatment and case management by a local health provider, by cleaning and bandaging the wound until the worm has been fully removed manually and by providing health education to discourage the patient from contaminating any water source (if two or more emerging worms are present, transmission is not contained until the last worm is removed); AND
4. Within seven days of the worm emerging, a GWEP supervisor determines that the above criteria have been met and the case is truly GWD; AND
5. The approved chemical temephos is used to treat potentially contaminated surface water if there is any uncertainty about contamination or if contamination was known to have occurred and if the water body in question meets certain other logistical criteria.

Safe Water

Safe drinking water sources include bore-hole wells and deep hand-dug wells with protective walls around them that prevent contaminated water from flowing back into the well (e.g., after rains or floods or if someone pours/spills water nearby the well). Flowing water, such as that found in a stream or river, is also safe from Guinea worm. The GWEP advocates for the development and maintenance of safe drinking water sources. It also encourages treatment of potentially contaminated drinking water. Fine-mesh cloth filters are given to households to strain out copepods (tiny “water fleas” too small to be clearly seen without a magnifying glass) from contaminated drinking water where there are no safe water supplies. People who travel or work away from the household and might not have access to filtered water are given individual pipe filters. These devices are used like straws to drink water from unsafe water sources.

Vector Control

A vector is an organism that carries or transmits disease. The vector for GWD is the copepod. To control this vector, the GWEP puts a measured amount of the approved chemical temephos (ABATE®*) into the water sources that are suspected or known to be contaminated with Guinea worm-infected copepods. This chemical kills the infected copepods and prevents people from becoming infected with GWD when they drink the water.

Health Education and Community Mobilization

Health education and community mobilization are important aspects of GWD eradication. Activities include the following:

• Teaching communities about the disease and how it is spread
  • Educating people during household visits by GWEP volunteers and staff and through organized events, such as Worm Weeks
• Helping villagers take action against the disease
  • Preventing people with emerging worms from entering and contaminating drinking water supplies
  • Using water filters to protect against GWD
• Helping villagers understand the need for safe chemical treatment (temephos) in their water supplies

*Use of trade names is for identification only and does not imply endorsement by the Public Health Service or by the U.S. Department of Health and Human Services.

What is dracunculiasis?

Dracunculiasis, also known as Guinea worm disease (GWD), is an infection caused by the parasite Dracunculus medinensis. A parasite is an organism that feeds off another organism to survive. 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. 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. GWD is considered by global health officials to be a neglected tropical disease (NTD ) and it is the first parasitic disease targeted for eradication.

Many federal, private, and international agencies are helping with the eradication of GWD. During 2018, Angola and South Sudan reported human cases; Chad and Ethiopia reported both human and animal cases; and Mali reported animal cases. Human cases have fallen from 3.5 million per year in 1986 to 28 in 2018. 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.

How does Guinea worm disease spread?

People become infected with Guinea worm by drinking water from ponds and other stagnant water containing tiny “water fleas” that carry the Guinea worm larvae. The larvae are eaten by the water fleas that live in these water sources.

Once drunk, the larvae are released from copepods in the stomach and penetrate the digestive track, passing into the body cavity. During the next 10–14 months, the female larvae grow into full-size adults. These adults are 60–100 centimeters (2–3 feet) long and as wide as a cooked spaghetti noodle.

When the adult female worm is ready to come out, it creates a blister on the skin anywhere on the body, but usually on the legs and feet. This blister causes a very painful burning feeling and it bursts within 24–72 hours. Immersing the affected body part into water helps relieve the pain. It also causes the Guinea worm to come out of the wound and release a milky white liquid into the water that contains millions of immature larvae. This contaminates the water supply and starts the cycle over again. For several days, the female worm can release more larvae whenever it comes in contact with water.

What are the signs and symptoms of Guinea worm disease?

People do not usually have symptoms until about one year after they become infected. A few days to hours before the worm comes out of the skin, the person may develop a fever, swelling, and pain in the area. More than 90% of the worms come out of the legs and feet, but worms can appear on other body parts too.

People in remote rural communities who have Guinea worm disease often do not have access to health care. When the adult female worm comes out of the skin, it can be very painful, slow, and disabling. Often, the wound caused by the worm develops a secondary bacterial infection. This makes the pain worse and can increase the time an infected person is unable to function to weeks or even months. Sometimes, permanent damage occurs if a person’s joints are infected and become locked.

What is the treatment for Guinea worm disease?

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 this process usually takes weeks. Medicine, such as aspirin or ibuprofen, can help reduce pain and swelling. Antibiotic ointment can help prevent secondary bacterial infections. The worm can also be surgically removed by a trained doctor in a medical facility before a blister forms.

Where is Guinea worm disease found?

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 certified 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.

Who is at risk for infection?

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.

Is Guinea worm disease a serious illness?

Yes. The disease causes preventable suffering for infected people and is a financial and social burden for affected communities. Adult female worms come out of the skin slowly and cause great pain and disability. Parents with active Guinea worm disease might not be able to care for their children. The worm often comes out of the skin during planting and harvesting season. Therefore, people might also be prevented from working in their fields and tending their animals. This can lead to financial problems for the entire family. Children may be required to work the fields or tend animals in place of their sick parents. This can keep them from attending school. Therefore, GWD is both a disease of poverty and also a cause of poverty because of the disability it causes.

Is a person immune to Guinea worm disease once he or she has it?

No. No one is immune to Guinea worm disease. People in affected villages can suffer year after year.

How can Guinea worm disease be prevented?

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.

This information is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the parasites described above or think that you may have a parasitic infection, consult a health care provider.

*Use of trade names is for identification only and does not imply endorsement by the Public Health Service or by the U.S. Department of Health and Human Services.