Guinea worm disease: Description, Causes and Risk Factors:
Guinea-worm disease is a crippling parasitic disease caused by Dracunculus medinensis (a species of skin-infecting, yard-long nematodes, formerly incorrectly classed as Filaria; adult worms live anywhere in the body of humans and various semi-aquatic mammals; the females migrate along fascial planes to subcutaneous tissues, where troublesome chronic ulcers are formed in the skin; when the host enters water, larvae are discharged from the ulcers, from which the head of the female worm protrudes; these larvae, if ingested by Cyclops species, develop in the intermediate host to the infective stage; humans and various animals contract the infection from accidental ingestion of infected Cyclops in drinking water. Popularly known as guinea, Medina, serpent, or dragon worm, and frequently thought to be the “fiery serpent” that plagued the Israelites)
, a long thread-like worm. The water-borne disease, which has afflicted humanity for centuries, is transmitted exclusively when people drink water contaminated with parasite-infected water fl eas and is now found in the most deprived regions of Africa.
Guinea worm disease used to thrive in some of the world's poorest areas, particularly those with limited or no access to clean water. In these areas stagnant water sources may still host microscopic arthropods known as copepods, which can carry the larvae of the guinea worm.
The larvae develop for approximately two weeks inside the copepods. At this stage the larvae can cause guinea worm disease if the infected copepods are not filtered from drinking water. The male guinea worm is typically much smaller (12-29 mm or 0.47-1.1 in) than the female, which, as an adult, can grow to 2-3 feet (0.61-0.91 m) long and be as thick as a spaghetti noodle.
Once inside the body, stomach acid digests the water flea, but not the guinea worm larvae that are sheltered inside. These larvae find their way to the body cavity where the female mates with a male guinea worm. This takes place approximately three months after infection. The male worm dies after mating and is absorbed.
The female, which contains larvae, burrows into the deeper connective tissues or adjacent to long bones or joints of the extremities.
Approximately one year after the infection began, the worm creates a blister in the human host's skin — usually on the leg or foot. Within 72 hours the blister ruptures, exposing one end of the emergent worm. This blister causes a very painful burning sensation as the worm emerges. Infected persons often immerse the affected limb in water to relieve the burning sensation. Once the blister or open sore is submerged in water, the adult female releases hundreds of thousands of guinea worm larvae, contaminating the water supply.
During the next few days, the female worm is capable of releasing more larvae whenever it comes in contact with water as it extends its posterior end through the hole in the host's skin. These larvae contaminate the water supply and are eaten by copepods, thereby repeating the life-cycle of the disease. Infected copepods can live in the water for only two to three weeks if they are not ingested by a person. Infection does not create immunity, so people can repeatedly experience guinea worm disease throughout their lives.
In drier areas just below the Sahara desert, cases of the disease often emerge during the rainy season, which for many agricultural communities is also the planting or harvesting season. Elsewhere, the emerging worms are more prevalent during the dry season, when ponds and lakes are smaller and copepods, thus, are more concentrated in them. Guinea worm disease outbreaks can cause serious disruption to local food supplies and school attendance
The disease is rarely fatal but infected people become nonfunctional for months and are unable to farm or do other work, resulting in increased poverty. In addition children affected by the disease are often unable to attend school.
Guinea-worm disease is easily prevented through simple measures such as filtering all drinking-water and educating infected people never to wade into water, which perpetuates the life-cycle of the disease. The disease places a major economic burden on affected villages and the cost in lost revenue for individuals and the community can be very high.
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
, 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 joints are infected and become locked.
The following studies are indicated in Guinea worm disease:
CBC count with differential: The WBC count is likely elevated, even if only slightly. The differential commonly indicates eosinophilia.
- Serum immunoglobulin levels: Immunoglobulin E (IgE), immunoglobulin G1 (IgG1), and immunoglobulin G4 (IgG4) levels are usually elevated, with variability depending on the stage of disease. Patent infections (immediately following blister eruption but before ulcer formation) cause the greatest elevation of the 2 IgG subclasses, whereas both are relatively less elevated with postpatent (ulcerated) or prepatent (blister in formative stage) infections.
A radiologic examination (plain-film roentgenography) of the lower extremity may prove useful in the identification of calcified worms in the rare case when surgery is considered. Incidental identification of calcified lesions from Guinea worm disease has also been reported after radiographic evaluation of a painful lower extremity.
There is no drug to treat Guinea worm disease (GWD) and no vaccine to prevent infection. Once the worm emerges from the wound, it can only be pulled out a few centimeters each day and wrapped around a piece of gauze or small stick. Sometimes the worm can be pulled out completely within a few days, but this process usually takes weeks or months. Analgesics, such as aspirin or ibuprofen, can help reduce swelling; antibiotic ointment can help prevent bacterial infections. The worm can also be surgically removed by a trained doctor in a medical facility before an ulcer forms.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.