DRACUNCULUS MEDINENSIS FIERY SERPENT MEDINA WORM THREAD WORM

DRACUNCULUS MEDINENSIS FIERY SERPENT/ MEDINA WORM/ THREAD WORM

Introduction Known as guinea worm disease. Also called serpent/medina/Thread worm. Vector borne parasitic disease. Involves subcutaneous tissues(leg and foot). Caused by nematode parasite, Dracunculus medinensis. Its not lethal but disable its victim temporarily.

Transmitted exclusively when people drink stagnant water contaminated with parasite infected water cyclops. It affects people in rural, deprived and isolated communities who depend mainly on open surface water sources such as ponds and wells. In India, the last case was reported in July 1996. On completion of three years of zero incidence, India was declared free of guineaworm disdease.

Dracunculus medinensis (Guinea Worm) Adult worms: Male 2 to 4 cm, Female 70 – 120 cms, viviparous Definitive host: Human: Intermediate host: Cyclops Infective form: Larva inside Cyclops Mode of transmission: Ingestion of water contaminated with cyclops Site of localization: Subcutaneous tissue

Cyclops

27/04/08 Dr Ekta, Microbiology

LIFE CYCLE Adult females are found in the sub-cutaneous tissues of man, Especially in the regions around the ankle, back and intermuscular connective tissues of the lower extremities of the body like arms and legs. The male and female attain their sexual maturity in the retroperiotoneal connective tissues and undergoes the process of copulation.

The male die after fertilising the female and gets calcified to remain there for about six months before getting disappeared. A fertilized female migrates to reach the selected parts of the host’s body which are liable to come in contact with water like arms, legs, knee, ankle joint and back (in case of water carriers). The adult female acquires its place in subcutaneous tissues of these parts.

On reaching the skin surface, female secretes a toxin which produces a blister of about 5 to 7 cm in diameter on the skin surface. The blister eventually breaks and an ulcer is formed. At the base of the ulcer appears a minute pore. Contact with water stimulates the worm to protrude its head and causes a reflex discharge of milky fluid, containing large number of embryos.

The female bear a large uterus in which several embryos remain lodged in coiled form. When the worm comes in contact with water, these embryos are liberated into outside water from the prolapse uterus. Further development of embryo occurs only when it reaches into the body of intermediate host.

After being liberated from the mother’s body the embryo wait for few days for its intermediate host. Cyclops belonging to class crustacea act as intermediate host for D. medinensis. The embryos are ingested by cyclops, 15 to 20 embryos can be ingested and accommodated in the stomach of a single cyclop without causing much inconvenience.

The normal life span of cyclop is about 3 to 4 months, but the infected cyclop die in about 42 days in ordinary infection and in about 15 days in case of heavy infection. Larvae require 15 days for their development in these cyclops. Cyclops act as INTERMEDIATE HOST. Man acquires infection by drinking water containing infected cyclops.

In human body cyclops are digested by gastric juice, parasites are released. These parasites can penetrate the duodenal wall. Migrate through the viscera to the subcutaneous tissues of various parts of the body. Grow into adult worms in 10 -14 months.

Clinical Features Disease – Dracunculosis Intense burning pain localized to path of travel of worm(the fiery serpent). Fever, Nausea, Vomiting Allergic reaction Arthritis and paralysis (due to death of adult worm in joint).

Clinical Features Clinical features develop an year after infection following the migration of worm to the subcutaneous tissue of the leg Blister formation – rupture of blister when in contact with water - ulceration – release of larvae by adult female worm Secondary bacterial infection of ulcer

Diagnosis Detection of adult worm – when it appears at the surface of skin Detection of larva – in milky fluid released by worm on exposure to water Radiology – calcified worm in deeper tissues

Treatment • Thiabendazole/ Metronodazole – symptomatic relief, easy removal of worm • Gradual extraction of worm by winding of a few cms on a matchstick per day, over 3 to 4 weeks Worms are removed by sequentially rolling them out over a small stick. ‘ROD OF ASCLEPIUS” • • Surgical excision

‘ROD OF ASCLEPIUS’ ‘FIERY SERPENT’

Prevention Drinking water should be boiled or filtered before being consumed. Water bodies and water supply should be chemically treated to kill cyclopses. Introduction of larvivorous and cyclopivorous fishes in water bodies. Discouraging the use of step wells