Dracunculiasis

Updated: Feb 01, 2016
  • Author: Vinod K Dhawan, MD, FACP, FRCPC, FIDSA; Chief Editor: Russell W Steele, MD  more...
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Overview

Background

Dracunculiasis is an infection caused by the nematode Dracunculus medinensis, also known as the guinea worm. D medinensis is in the order Spirurida, an order of parasites that includes the filariae Wuchereria bancrofti, Brugia malayi, and Loa loa.

The term dracunculus is Latin for "little dragon," a misnomer and reference to the symbol. Thus, when the guinea worm disappears, one of the original inspirations for the discipline of medicine will also disappear. Currently, the infection persists and, although uncommon, can cause significant morbidity.

During ancient times, the presence of dracunculiasis can be inferred by the universally recognized symbol of medicine, the Greek asklepios (ie, Roman aesculapius), which consists of a one-headed snake wrapped around a stick. Dead female worms have also been found in Egyptian mummies older than 3000 years, and writings in ancient Sanskrit, Greek, and Hebrew refer to Dracunculus infection. To this day, the most effective method dracunculiasis treatment involves extraction by wrapping the worm around a stick, as is seen in the image below.

A method used to extract a guinea worm from the le A method used to extract a guinea worm from the leg vein of a human patient.

During the last 25 years, concerted efforts to eradicate the guinea worm have been undertaken and these have resulted in a reduction of more than 99% of worldwide cases of dracunculiasis. Thanks to a relentless campaign, this is poised to become the first disease since smallpox to be pushed into oblivion. The Carter Center has led the effort to eradicate the disease, along with the CDC, the WHO, UNICEF, and the Bill and Melinda Gates Foundation.

Guinea worm disease remains endemic in 3 countries: Sudan, Mali, and Ethiopia and fewer than 1,800 cases were reported in the world in 2010. The most prominent hot spot for guinea worm disease is South Sudan, which harbors 94% of current cases. Sporadic violence and civil unrest in Sudan and Mali poses the greatest threat to the final eradication of dracunculiasis.

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Pathophysiology

Dracunculiasis is caused by drinking water containing water fleas (Cyclops species) that have ingested Dracunculus larvae. The acidic environment of the stomach and duodenum kills the copepods. The larvae are subsequently released in the stomach or small intestine and penetrate the mucosa to mate and mature in the abdomen or retroperitoneal space approximately 60-90 days after initial infection. The maturation stage can last for up to 1 year, and, during this time, the adult male probably dies because only the female worm is recovered from symptomatic patients.

After maturation is complete, the female Dracunculus reaches a length of up to 1 m (with a thickness of only 1-2 mm) and slowly migrates from the GI tract into subcutaneous tissue, usually to a location in the lower extremity. The female worms move through the person's subcutaneous tissue, causing intense pain, and eventually emerge through the skin, usually at the feet, producing edema, a blister and eventually an ulcer, accompanied by fever, nausea, and vomiting. If they come into contact with water as they are emerging, the female worms discharge their larvae, setting in motion a new life cycle. Free-living larvae can survive only 3 days without a host; they become infective after 2 weeks (2 molts) within the host copepod.

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Epidemiology

Frequency

United States

Dracunculiasis is rarely imported to the United States. Two cases have been reported since 1995, both occurring in individuals from Sudan.

International

In 1986, more than 3.5 million people in 20 countries were infected with guinea worm.

At the end of 2004, all of Asia was free of the disease. Sporadic cases have been noted in Australia and North America in African immigrants during the period 2000-2005. Since 2006, only sporadic cases have been reported in African nations.

From 2007-2008, indigenous infections were limited to focal areas of four countries in sub-Saharan Africa: Sudan, Ghana, Mali, and Niger. Currently, guinea worm disease remains endemic in 3 countries: Sudan, Mali, and Ethiopia and fewer than 1,800 cases were reported in the world in 2010. The most prominent hot spot for guinea worm disease is South Sudan, which harbors 94% of current cases. [1, 2, 3, 4]

There were 126 cases reported worldwide in 2014. South Sudan reported 56% of the Guinea Worm Disease (GWD) cases in 2014. The remainder of the 2014 GWD cases were from Chad, Ethiopia, and Mali. [5]

Mortality/Morbidity

Death due to dracunculiasis is not caused by the primary infection and occurs only in cases in which secondary infection of the worm's exit site leads to sepsis. The mortality rate is quite low; however, morbidity is a major concern, with secondary infection being the most common complication. Cellulitis or the formation of an abscess requires prompt attention, and pain from the exit sites often can incapacitate patients for weeks. This is usually observed in individuals who have multiple worms and rely on their ability to stand or walk for their livelihood. Farmers with untreated dracunculiasis in Nigeria have been found to miss work for up to 3 months. Infected schoolchildren may miss up to 25% of the school year. Therefore, Dracunculus infection can cause significant socioeconomic burden for individuals and communities.

Another, more chronic, complication of dracunculiasis is encapsulation of the adult worm, which occurs when the calcified remains of the worm persist in the extremity of the patient. This can result in chronic pain and intermittent swelling of the extremity. In a small percentage of individuals who have permanent scarring or deformity of the lower extremity, even after the worm has been extracted, chronic pain may persist for as long as 18 months. Notably, on average, infected individuals have multiple worm extrusions at the same time (1.8 worms per person, on average). Rarely, dracunculiasis can present with worms located in anomalous locations, including the lungs, pancreas, testes, spinal cord, or periorbital tissue.

Race

No race predilection is noted.

Sex

No sex predilection is observed.

Age

Most reported dracunculiasis cases occur in the young adult (working) population who may be exposed to contaminated water sources more frequently; however, no particular age predilection is noted.

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