Dracunculus medinensis : Epidemiology, Laboratory Diagnosis & Treatment

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Diseases caused by Guinea worm Dracunculosis, also known as guinea worm infection, is found in Africa, India, Asia, Pakistan, and the Middle East. Copepods live in fresh water, particularly in areas known as step wells, where people get drinking water and bathe. Dracunculus medinensis larvae in their first stage escape from the ulcers of infected people who come into contact with this water. Ponds, man-made water holes, and standing water can all be infection sources. Dogs are one of the reservoir hosts that have been identified. These animals, like humans, become infected through contaminated drinking water.

Morphology of Dracunculus medinensis

Dracunculus medinensis Larvae

There are two stages of larvae. The diagnostic stage, also known as the first stage or rhabditiform larvae, is small, measuring 620 by 15 m on average. The tail is about one-third the length of the body and ends in a point. The third stage larvae, which live in an intermediate host, have received little attention.

 Dracunculus medinensis larvae
Dracunculus medinensis larvae

Adults Dracunculus medinensis

The average elongated female Dracunculus medinensis measures approximately 840 mm long by 1.5 mm wide and is considered one of the largest adult nematodes. The female has a prominent blunt, rounded front end. The adult male is much smaller than the female, measuring only 21 by 0.4 mm.

The male’s anterior end coils on itself a minimum of one time.

Dracunculus medinensis adult
Dracunculus medinensis adult

Life Cycle of Dracunculus medinensis

  • Human infection begins with the consumption of contaminated drinking water tainted with infected copepods (freshwater fleas).
  • These copepods contain infective D. medinensis third-stage larvae, which emerge into the intestine after human ingestion.
  • The larvae develop into adult worms, pass through the intestinal wall, and then move on to connective tissues or body cavities.
  • After mating, gravid female worms migrate into subcutaneous tissue, particularly the skin of the extremities, where they lay live first-stage larvae.
  • When all of their larvae are released, the adult females may flee the body at the larvae deposit site or migrate back into deeper tissues, where they are eventually absorbed.
  • The adult males’ fate is unknown. At the site of the larvae deposit, an infected ulcer develops.
  • When exposed to suitable conditions, such as cool freshwater, the ulcer ruptures, releasing the larvae into the water.
  • Copepods in the water eat the first-stage larvae, acting as an intermediary host.
  • The larvae then mature into their third-stage infective form. Ingestion of the infected copepod restarts the cycle.
Life Cycle of Dracunculus medinensis
Life Cycle of Dracunculus medinensis

Clinical Symptoms of Dracunculosis, Dracunculiasis

Guinea Worm Infection: Dracunculosis, Dracunculiasis

Patients infected with guinea worm typically experience symptoms similar to allergic reactions as the organism migrates. Secondary bacterial infections may also develop, with some resulting in disability or even death. A painful ulcer develops at the site where the gravid female settles into the subcutaneous tissues and lays her larvae. Unsuccessful attempts to remove an adult female worm may result in a partial worm remaining at the site and toxic reactions in the ulcer. Following the death and calcification of an adult worm, additional allergic reactions and nodule formation may occur.

Laboratory Diagnosis of Dracunculosis, Dracunculiasis

Adult D. medinensis worms can be recovered by observing infected ulcers for the worms to emerge. The first-stage larvae are revealed when the infected ulcers are ruptured by immersing them in cool water.

Treatment of Dracunculosis, Dracunculiasis

Because there are no specific dracunculiasis medications, successful treatment usually entails complete worm removal. The removal process is usually divided into five steps:

  • Step 1 entails immersing the affected body part, which is in the form of a blister, in cool water. Contact with water creates an environment that is appealing to the underlying adult worm.
  • Step 2: The adult worm breaks through the blister and is eager to explore the outside world.
  • Step 3: At this point, it is critical to thoroughly clean the resulting wound.
  • Step 4 is the manual extraction of the entire worm by winding it around a stick or a similar item that creates tension.
  • Step 5: Following the removal of the worm, this step is carried out, which consists of applying topical antibiotics to the wound site as a preventative measure against the emergence of secondary bacterial infections.

Prevention and Control of Dracunculosis, Dracunculiasis

  • The consumption of properly treated water, the boiling of water suspected of contamination, the prohibition of drinking and bathing in the same water, and the cessation of the practice of ingesting standing water are all logical guinea worm prevention and control measures.
  • Filtering suspected water with a finely meshed filter is one of the simplest ways to remove copepods. This measure is being implemented in endemic areas.
  • Aside from the fact that it is nearly impossible to educate the entire population in endemic areas, some people’s religious practices pollute the water. It is highly unlikely that the guinea worm will be completely eradicated in the near future.

Reference

Clinical Parasitology: A PRACTICAL APPROACH. Elizabeth A. Gockel-Blessing (formerly Zeibig) P. 228 – 230

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About the Author: Labweeks

KEUMENI DEFFE Arthur luciano is a medical laboratory technologist, community health advocate and currently a master student in tropical medicine and infectious disease.

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