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Guinea Worm Disease Frequently Asked Questions (FAQs)


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 of another organism to survive. GWD is spread by drinking water containing Guinea worm larvae. Larvae are immature forms of the Guinea worm. GWD affects poor communities in remote parts of Africa that do not have safe water to drink. GWD is considered by global health officials to be a neglected tropical disease (NTD). GWD is the first parasitic disease slated to be eradicated.

Those countries that still have local GWD cases are receiving help from many governmental, private and international organizations to eradicate this disease.  During 2016, only three countries reported local GWD cases: Chad, Ethiopia and South Sudan. Cases have gone from 3.5 million per year in 1986 to 25 human cases in 2016.  Chad also reported 1,013 Guinea worm-infected dogs in 2016.

How does Guinea worm disease spread?

People become infected with Guinea worm by drinking water from ponds and other stagnant water containing copepods (tiny “water fleas” too small to be clearly seen without a magnifying glass) that carry the Guinea worm larvae. The larvae are eaten by the copepods that live in these water sources.  Since 2012, Guinea worm disease (GWD) has been spreading among dogs in Chad.  The mechanism of spread among dogs is not known.  Dogs may not get GWD from drinking water like humans do.  One theory is that they become infected by eating an aquatic animal (e.g., a fish or frog) that itself has swallowed copepods that have fed on Guinea worm larvae in the water.

Once ingested, the Guinea worm larvae are released in the stomach of the human or dog and penetrate the digestive tract, 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 joint is infected and becomes 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.

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Where is Guinea worm disease found?

Only three countries reported local Guinea worm disease in 2016. These countries were Chad, Ethiopia and South Sudan. Many other African countries and all of Asia are now free of GWD. As of March 2016, the World Health Organization had certified 198 countries, territories and areas including 186 WHO Member States, as being free of GWD transmission.

Who is at risk for infection?

Anyone who drinks water from a pond and/or another stagnant water source contaminated with Guinea worm larvae is at risk for infection. Larvae are immature forms of the Guinea worm. In Chad, dogs are also getting GWD and many more dogs than humans are infected.  In 2016, about a dozen dogs with GWD have also been reported in both Ethiopia and Mali. It is not clear how dogs are getting GWD. One thought is that they are eating aquatic animals (e.g., fish or frogs) that have swallowed copepods (tiny “water fleas”) that have fed on Guinea worm larvae in the water.

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. Adults with active Guinea worm disease might not be able to work in their fields or tend 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. Children who have GWD themselves may also be unable to attend 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?

Guinea worm disease can be prevented by avoiding drinking unsafe water. Teaching people to follow these simple control measures can completely prevent the spread of the disease:

  • Drink only water from protected sources that are free from contamination (such as from boreholes or hand-dug wells protected by a wall around the opening and a cover over the hole).
  • Prevent people with swellings, blisters, wounds and hanging Guinea worms from entering ponds and other water used for drinking.
  • Always filter drinking water from unsafe sources, using a cloth filter or a 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.
  • Treat unsafe drinking water sources with an approved larvicide, such as ABATE®*. This will kill the copepods that carry the Guinea worm larvae.
  • Provide communities with new safe sources of drinking water and repair broken safe water sources (e.g., hand-pumps) if possible.
  • Educate villagers to cook their fish well, to bury fish entrails left over from fish processing, and to not allow their dogs to eat fish entrails.
  • Encourage dog owners to tether infected dogs until the worms emerge to prevent the dogs from entering and contaminating water.

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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.