Dracunculiasis or Guinea Worm Disease: General Overview
Author: Thomas C. Weiss
Contact : Disabled World
Information regarding Guinea worm disease, a condition caused by a parasitic worm that migrates through subcutaneous tissues causing severe pain.
Guinea worm disease is caused by the parasitic worm, 'Dracunculus medinensis,' or, 'Guinea-worm.' The worm is the biggest of the tissue parasites which affect people. The adult female, which carries approximately three million embryos, can measure 600-800 mm in length and two mm in diameter. The parasite migrates through a person's subcutaneous tissues causing severe pain, particularly when it occurs in a person's joints. The worm eventually emerges, from the person's feet in most instances, causing intensely painful oedema, a blister and an ulcer accompanied by nausea, fever and vomiting.
People who are infected attempt to relieve the burning sensation by immersing the infected portion of their body in local water sources, often times ponds of water. Doing so also induces a contraction of the female worm at the base of the ulcer, causing the sudden expulsion of hundreds of thousands of first stage larvae into the water. The larvae move actively in the water where they may live for a few days.
For additional development, the larvae need to be ingested by suitable species of voracious predatory crustacean, Cyclops or water fleas which measure 1-2 mm and widely abundant around the world. In the Cyclops, larvae develop to infective third-stage in 14 days at 26C.
When someone drinks contaminated water from ponds or shallow open wells, the Cyclops is dissolved by the gastric acid of the stomach and the larvae are released and migrate through the person's intestinal wall. After 100 days, the male and female meet and then mate. The male becomes encapsulated and dies in the tissues, while the female moves down the person's muscle planes. After around a year of the infection, the female worm emerges – often from the person's feet, releasing thousands of larvae and repeating the guinea worm life cycle.
Fig 1. Diagram of the life cycle of Dracunculus medinensis
There is no drug available to either prevent or heal this parasitic disease, exclusively associated with drinking water that is contaminated. Dracunculiasis is; however, fairly easy to eliminate and eventually eradicate. Guinea worm disease is rarely fatal. Frequently, the person remains ill for several months, mainly because:
- Accidental rupture of the worm in the tissue spaces might result in serious allergic reactions.
- The migration and emergence of the worms happen in portions of the body which are sensitive, at times the articular spaces may lead to permanent disability.
- The emergence of the worm, at times several, is accompanied by painful oedema, intense generalized pruritus, ulceration and blistering of the area from which the guinea worm emerges.
- Ulcers caused by the emergence of the guinea worm invariably develop secondary bacterial infections which exacerbate pain and inflammation, resulting in temporary disability ranging from a few weeks to several months.
Temporary disability might leave many people unable to leave their beds for a month either during or after the emergence of the worm, some that usually happens during the peak agricultural activities and when labor is in high demand. The epidemiology of the disease is largely determined by the use of open stagnant water sources such as ponds, or shallow or steep wells. Man-made ponds are the primary source of transmission.
Guinea worm disease is seasonal, happening with two broad patterns found in endemic areas of Africa, depending upon climatic factors. In the, 'Sahelian,' zone transmission usually happens in the rainy season from May to August. In the humid Savanna and forest zone, the peak occurs during the dry season from September to January. There are; however, local variations in these patterns. Additional risk factors are infection and mobility having occurred in the prior year.
Guinea worm disease is a vulnerable one; people alone are responsible for maintaining its fragile transmission cycle. It is possible to permanently curtail transmission through application of the measures below:
- Treatment of Unsafe Water Sources: Treatment of unsafe water sources with, 'temephos,' to kill the Cyclops.
- Ensuring Access to Safe Water: Ensuring access to safe drinking water and converting unsafe sources of water to safe ones.
- Effective Surveillance: Effective surveillance to detect all instances within 24 hours of worm emergence and containment of all instances.
- Health Education/Social Mobilization: Health education and social mobilization to encourage affected communities to adopt healthy drinking water behaviors.
- The Construction of Copings: The construction of copings around well heads, or the installation of boreholes with hand pumps, which would prevent not only Dracunculiasis, but also diarrheal diseases.
- Regular and Systematic Filtering of Water: Regular and systematic filtering of drinking water from ponds and shallow, unprotected wells or from surface water. Finely-meshed cloth or a filter made from a 0.15 mm nylon mesh is all that is required to filter the Cyclops from drinking water.
If the measures above are implemented by village communities, the ultimate goal of eradicating guinea worm disease will be achieved. From recent reports, the world is a mere two years away from eradicating the guinea worm, in part thanks to former President Jimmy Carter.
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