DRACUNCULIASIS

Lauren Heiser

Dr. D. Scott Smith

Human Biology 103

 

INTRODUCTION:

Today, dracunculiasis, more commonly known as Guinea Worm Disease, is only found in 13 countries in sub-Saharan Africa. It is caused by a nematode, or flatworm, Dracunculus medinensis, which infects small Crustaceans, called Cyclops which dwell in water supplies. Human because infected if they drink from an unfiltered water supply, which contains infected water fleas.

As the World Health Organization states, although dracunculiasis is not a cause of mortality, "it is a real burden in terms of morbidity, incapacity and suffering for those affected1." Those infected by the disease are most often rural farm workers, who, after contracting the disease, are often not able to work or take care of their children for months.

As will be explained further, eradication of the disease is relatively simple and is in near sight--eradication can be accomplished simply by preventing people from drinking from water contaminated by the parasite.

After Small Pox, Guinea Worm Disease will be the second disease to be eliminated from the world2.


Parasite

Means of Human Infection

Location of Larvae in Humans

Location of Adults in Humans

Clinical Features

Laboratory Diagnosis

Dracunculus medinensis

(Guinea Worm)

Ingestion of larvae in infected copepods (Cyclops and others)

Intestinal tract, deep connective tissue

Deep connective tissues, subcutaneous tissue, dermis

Pruritus, blister, ulcer, eosinophilia, secondary infection

Adult worm in lesion, larvae from worm in ulcer

*Table taken from page 354 of Markell and Voge's Medical Parasitology by Edward K. Markell, Ph.D., M.D.

AGENT:

Dracunculus medinensis (tissue nematode)

SYNONYMS:

Guinea Worm Disease

MORPHOLOGY:

Adult female worms can measure up to one metre in length and 2mm across3. Less conspicuous male worms average only 2cm long4.

RESERVOIRS:

No known animal reservoirs.

INTERMEDIATE HOST/VECTOR:

Cyclops--small (.5-2 mm) Crustacean

 

HISTORY OF DISCOVERY:

Dracunculiasis is documented as early as the 15th century BC in Egypt. A description of the disease is found in the "Turin Papyrus," which describes the ancient myth of the Egyptian sun god. This documentation was recently supported by the pathological examination of an Egyptian mummy in which a calcified worm was identified as Dracunculus medinensis5. Similar documentation, dating back to 11th century AD, has also been found in Persia and Israel.

It wasn't until the 18th century that that Swedish naturalist Carolus Linnaeus first suggested that the "fiery serpents" plaguing Middle Eastern countries were a type of parasitic worm. Finally, in 1870, Alexei P. Fedchenko discovered the life cycle of the Guinea Worm and the intermediate host--the Cyclops.

Beginning in the early 1920's, world-wide eradication programs were first implemented which focused on water sanitation in an effort to eliminate the Cyclops and therefore dracunculiasis from public water supplies. These efforts have continued throughout the 20th and 21st centuries. In 1980, one of the goals set for the International Water Supply and Sanitation Decade (1981-1990), by the World Health Organization in collaboration with the United Nations, was the eradication of dracunculiasis6. Finally, as states on the website for the Center for Disease Control, "In May 1991 the Forty-fourth World Health Assembly endorsed the goal of eradicating dracunculiasis (guinea worm disease) by the end of 1995 (resolution WHA44.5)7." This goal has been reached in numerous areas of the world, including Pakistan (last case reported in 1993), Iran (last case reported in the mid-1970's), and India (last case reported in 1997)8. All current endemic areas are in sub-Saharan Africa.

CLINICAL PRESENTATIONS:

Symptoms include pain in joints, nausea, fever, pruritus, blisters, ulcers, eosinophilia, and secondary infections9. In the best case scenario, after extraction of the worm, the patient may only be disabled for 2-4 weeks. However, more often than not, the patient remains incapacitated for several months, due to the presence of multiple worms, the sensitivity of areas of the body which worms migrate to and through (such as the soles of the feet) and serious secondary bacterial infections11. The is no way to guarantee immunity.

People in remote, rural communities are most commonly affected by Guinea worm disease. These patients most often do not have access to medical care. Ulcers may therefore take many weeks (8 weeks average) to heal and often become infected, causing complications such as locked joints or even permanent crippling. Each time a worm emerges, persons are often unable to work and resume daily activities for an average of 3 months. This usually occurs during planting or harvesting season, resulting in heavy crop losses. Parents who have active Guinea worm disease cannot care for their children. They also cannot tend or harvest or crops, which leads to financial problems for the entire family.

 

 

 

 

 

TRANSMISSION:

As described by the Carter Center, on their website: http://www.cartercenter.org.

  1. Person drinks well or pond water containing Cyclops, small crustaceans known also as "water fleas," that are infected with mature (third stage) worm larvae.
  2. Gastric juices in the human stomach digest the Cyclops and worm larvae are released and within two weeks, move into the abdominal tissue where they mature and mate.
  3. Fertilized female worms migrate to various body regions, usually the lower limbs, and male worms die soon after mating.
  4. Approximately one year after infection, the female worm emerges at the site of a painful blister (found 90% of the time on the foot).
  5. The infected person will most often rush to a water source, and place the limbs with the blister in water to relieve some of the pain. As soon as the emerging worm comes into contact with water, the worm release 1-3 million larvae into the water source, often a pond or shallow well.
  6. Cyclops then swallows the larvae (a free living larvae only survives for 3 days without a host).
  7. The parasite punctures the digestive tract of the Cyclops and makes its way to the abdomen, where it develops into an infectious (3rd stage) larvae, which can infect humans. 1-3 weeks after the larvae reaches the infectious stage, the Cyclops, which can no longer swim, sinks to the bottom of the water supply and dies.

 

INCUBATION PERIOD:

In Cyclops: After the Cyclops swallows the embryonic parasite, it takes approximately two weeks for the parasite to puncture the digestive tract, make its way to the abdomen, and develop into an infectious larvae. 1-3 weeks after the larvae reaches the infectious stage, the Cyclops, which can no longer swim, sinks to the bottom of the water supply and dies12.

In Humans: Symptoms of the disease start to appear one year after a human drinks water containing an infected Cyclops, when the full-grown female worm starts to make its way through the body13.

 

DIAGNOSTIC TESTS:

The only way to diagnose this disease is to locate an adult worm in the lesion, or larvae from the adult female worm in the ulcer14.

MANAGEMENT AND THERAPY:

There are no drugs to combat or vaccinate against the parasite, nor are there any drugs, besides pain reduces, to treat any of the clinical symptoms.

EPIDEMIOLOGY:

Valiant world-wide eradication efforts have decreased the number of cases of Dracunculiasis from 3.2 million cases in 1986 to less than 75,000 in 2000, as stated in a news release issued by the Carter Center on May 21, 200115. All remaining endemic areas are found in 13 countries in sub-Saharan Africa.

COUNTRY INFORMATION:

73% of all reported cases are found in Sudan: "In 2000, The Sudan Guinea Worm Eradication Program (SGWEP) reported more than 54,000 new cases of Guinea worm disease (actual number of cases in Sudan is unknown) from 3,386 villages16."

PUBLIC HEALTH AND PREVENTION:

Initiating water sanitation efforts in endemic areas can easily eliminate Dracunculiasis. These efforts should include health education interventions, which address the following:

    1. The importance of drinking clean water, free from contamination.
    2. The importance of preventing persons with an open Guinea worm ulcer from entering ponds and wells used for drinking water.
    3. How to filter water fleas from drinking water.
    4. How to treat contaminated water sources with a chemical, such as Abate, that kills water fleas.

A program to eliminate Guinea Worm disease from Sudan (the area with the highest rate of infection) was recently describes in a news release issued by the Carter Center on May 21, 2001. Organizations such as the Carter Center, Health and Development International (HDI), Hydro Polymers of Norsk Hydro, and Norwegian Church Aid (NCA), has begun to distribute 9 million pipe filters--one for every man, woman and child at risk of this disease17. The pipe filters can we worn around the neck, in case residents have to quickly flee as a result of war, which has plagued the country for the past 20 years.

 

USEFUL WEBSITES:

http://www.cartercenter.org

http://www.who.int

http://www.mednets.com

http://www.cdc.gov

 

 

 

ENDNOTES:

1 http://www.who.int/ctd/dracun.index.html

2 http://www.cartercenter.org/NEWS/RLS2001/pr-sudanguineaworm.html

3 http://www.who.int/ctd/dracun/disease.htm

4 Markell, Edward. Medical Parasitology. Philadelphia: W.B. Saunders Company, 1999: 337.

5 http://www.who.int/ctd/dracun/dates.htm

6 http://www.who.int/ctd/dracun/dates.htm

7 http://wonder.cdc.gov/wonder/prevguid/p0000415/p0000415.asp

8 http://www.who.int/ctd/dracun/progress.htm

9 Markell, Edward. Medical Parasitology. Philadelphia: W.B. Saunders Company, 1999: 354.

10 http://www.who.int/ctd/dracun/disease.htm

11 http://www.who.int/ctd/dracun/disease.htm

12 http://www.who.int/ctd/dracun/disease.htm

13 Markell, Edward. Medical Parasitology. Philadelphia: W.B. Saunders Company, 1999: 354.

14 http://www.cartercenter.org/NEWS/RLS2001/pr-sudanguineaworm.html

15 http://www.cartercenter.org/NEWS/RLS2001/pr-sudanguineaworm.html

16 http://www.cartercenter.org/NEWS/RLS2001/pr-sudanguineaworm.html

17 http://www.cartercenter.org/NEWS/RLS2001/pr-sudanguineaworm.html