Female 60 cm in length, reported up to 3 m. Male much smaller, 1.2-2.9
cm long. Juveniles (larvae) 500-700 um long.
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
Also found in India, Pakistan, Saudi Arabia, and Yemen.
Inhabits freshwater lakes and rivers.
Dracunculus medinensis, the guinea worm, historically infected approximately 10 million
people per year. An eradication program led by the
Carter Center has drametically
reduced the number of infections and there is hope of eradication of the
disease. The majority of human infections occur in parts of West
Africa, East Africa, and India.
The efforts of the Carter Center, have resulted
in a decrease of human cases from 3.5 million in 1986 to 30 in 2017.
In south-eastern Nigeria the guinea worm disease, dracunculiasis, is responsible for an 11.6% decrease in the total rice crop, valued at $20
million (how? contamination? labor inefficiencies?).
The guinea worm has been blamed for the majority of school absences in many parts of Africa, wasting valuable time and resources in already-poor third world countries.
Dracunculus medinensis is parasitic, feeding on the blood of its
Definitive hosts are humans
The guinea-worm like all filarial nematodes goes through six developmental
stages. The however unlike any other filarial parasite that can be transmitted
to humans the infective larvae enter the body through the ingestion of various
species of the freshwater crustacean Cyclops in contaminated water.
Cyclops sp. (Peters and Gilles 1991).
Inside the definitive (vertebrate) host, the ingested Cyclops is
destroyed by stomach acids. The free larvae penetrate the gut lining and migrate
to subcutaneous tissues via the lymphatic system. This process takes
approximately 43 days and once in subcutaneous tissue the worms mature slowly,
reaching full development in one year.
As adults, the nematodes mate. The small male (1.2-2.9 cm long) dies
and is absorbed into the larger female (60 cm long). When the embryos in the
uterus reach maturity, the female nematode migrates to areas of the body in
contact with water (90% move to the feet and legs). Once in these areas the worm
penetrates the skin, extrudes its uterus through its mouth, and discharges
larvae into the water and dies.
from Peters and Gilles 1991)
The larvae, which measure between 500 and 700 m, can live for 6 days in
clean water and 2 to 3 weeks in muddy water (photograph from Peters and Gilles
The larvae are ingested by the copepod crustacea, Cyclops, which
actively chase them. Once ingested, the larvae mature into their infective stage
in approximately 14 days and can then reinfect humans.
After mating inside the definitive (human) host, the female burrows through the skin, creating an ulcerated
area, usually in a lower part of the host's anatomy.
When the ulcerated area is exposed to water (as in a river or lake), the female's uterus ruptures, releasing many
juveniles into the water.
Feeding on blood, impairment of lymphatic system(?), skin ulceration.
The female guinea-worm
lives in the connective tissues of the limbs and trunk usually without
noticeable pathological conditions. Although heavy infestations in the
joints can cause arthritic conditions and require the removal of the worms
(picture from Peters and Gilles 1991), most pathology is associated with
infection occurring when the female dies after discharging her larvae.
death of the worm causes the formation of an abscess which, when secondarily
infected, results in cellulitis and local blistering of the skin (picture from
Peters and Gilles 1991).
Also, chills, fever and local painful swellings commonly precede the
emergence of the worm. D. medinensis has also been found coiled in the
hernial sac and in the placenta, causing bleeding in pregnancy.
There is a worldwide effort to eradicate the Guinea worm. Organizations such as the Task Force for Child Survival and Global 2000 list this as one of their primary objectives.
Spread of the Guinea worm can be prevented by filtering drinking water through a cotton cloth or by treating drinking water with the chemical Abate (which has been tested to be safe for human consumption, and it is not known to harm birds or fish).
The best method for defeating dracunculiasis seems to be supplying villages
with safe drinking water.
Material from Mark Potter, 1995 and from the Filarial Genome Network