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Dracunculiasis (dracontiasis, guinea worm disease) is caused
by infection of subcutaneous and connective tissues with the guinea worm Dracunculus
medinensis. Humans are the only known reservoir. Once a
scourge affecting thousands of people around the world, the range
of this organism has been greatly reduced as a result of a global
eradication program spearheaded by the Carter Center’s Global
2000 program. After an estimated 3.5 million cases in 1986, 25,217
cases were reported in 2006.1Over 180 countries
have now been certified as free of guinea worm by the World Health
Organization. Currently, the Carter Center and the Centers for Disease Control
and Prevention (CDC) estimate that the incidence of guinea worm
infection fell by 95% between 1986 and 1996 such that it
is now estimated that there are fewer than 10,000 cases, which are
limited to five African countries—Sudan, Ghana, Nigeria,
Niger, and Mali. Sudan alone accounts for more than two thirds of
the total cases reported worldwide. Virtually all cases occur in
rural, isolated areas. The economic impact of infection is significant,
with adults losing about 100 days of work and children missing 25% of
school when symptomatic.2,3
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When an individual drinks water contaminated with freshwater
copepods (plankton) of the genus Cyclops, which
contain mature guinea worm larvae, infective larvae are set free,
penetrate the intestinal wall, and usually migrate to the retroperitoneal
tissues (eFig. 326.1).4 Sixty
to 90 days after infection, mating occurs and the males subsequently
die. Females then require about 8 to 12 months to mature. The gravid
female worm, averaging 1 m in length by 1 to 2 mm in diameter (eFig. 326.2), usually migrates
from the deep connective tissues to emerge in the superficial subcutaneous
tissues of the distal portions of the arms and legs. More than 90% of
worms emerge from the lower extremities, mainly below the knees.
Following development of an indurated papule, a painful skin blister
forms near the anterior portion of the worm, and infected individuals
frequently immerse the affected limb into water to relieve the pain.
The affected area ulcerates and when the ulcer is immersed in water,
large numbers of motile larvae are discharged into the water through
a ruptured prolapsed loop of the parasite’s uterus (Fig. 326-1). If larvae are expelled into
a body of water used for drinking, such as a pond, they may be ingested
by copepods and the cycle repeats.5
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