Dracunculiasis follows ingestion of freshwater contaminated with copepods (water fleas) that contain the parasitic nematode Dracunculiasis medinensis. The affliction is ancient. It has been identified in a 3,000- year-old mummy and is believed to be described in the Old Testament as the “fiery serpent” responsible for torturing the Hebrews during their exodus from Egypt.
Mortality is generally low, but secondary bacterial infections may be life-threatening due to lack of access to health care in most endemic areas. Associated painful and infected ulcers can substantially impair mobility and incapacitate patients for weeks or months.
Transmission occurs by accidental consumption of tiny Cyclops copepods, often found in stagnant pond water, that have ingested D medinensis larvae. Though stomach digestive juices kill the copepods, the larvae of the Guinea worm survive and penetrate the stomach or small intestinal wall, migrating to the subcutaneous tissue of the abdomen and thorax. During the next 2 to 3 months, these larvae develop into adult worms and mate. The male worms die shortly after copulation while females continue to mature and burrow into connective tissue and along long bones.
Approximately a year following initial infection, female worms emerge through the dermal surface. Dependent regions including the foot and lower leg are the most common exit points, although any part of the body can be involved. Often multiple worms can appear at the same time as many as 40 or more have been documented to emerge simultaneously.
A blister forms at the site of egress, and the associated burning sensation elicited by worm penetration is relieved by soaking the affected limb.
Submerging the affected body part in water triggers gravid females to release hundreds of thousands of microscopic larvae, a particularly unfortunate occurrence when released in a community water source. These larvae are then ingested by copepods, completing the life cycle.
Symptoms from migrating adult parasites are rare but may include an urticarial rash, fever, nausea, vomiting, diarrhea, and dizziness. Worms emerge over a period of weeks and produce intensely painful edema, blistering, and ulceration. Baseline health and nutritional status play important roles in determining the rate and success of ulcer healing.
The process may be prolonged and, in many cases, is complicated by secondary bacterial infection, abscess formation, septic arthritis, sepsis, or tetanus. Joint infection may result in deformities and limb contractures. The mean length of disability is 10 weeks, although some patients experience continuing pain for an additional 12 to 18 months.
Guinea worms are diagnosed clinically as they approach dermal tissue and form a painful papule, which subsequently enlarges and ruptures to expose the adult worm. Immersion of affected body parts in water can lead to a characteristic “white cloud,” representing release of larvae.
At present, no medications are available to treat or prevent dracunculiasis. Pain is addressed symptomatically with analgesics, although these are rarely available in the remote areas where the disease remains endemic. Antibiotics are critical for management of superinfections.
Affected limbs should be kept clean, disinfected, and bandaged. Emerging worms are easily torn if pulled with force. Instead, extrusion is facilitated by curling worms around a small stick and manually winding them several centimeters daily. This method, which is painful and can take up to a month, has been practiced for centuries. Some scholars suggest that this traditional treatment for Guinea worm is the basis for the caduceus and staff of the Aesculapius symbol of medicine.