Guinea Worm Disease (Dracunculiasis)

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Introduction

  • An infection by a very long nematode, Dracunculus medinensis
  • Contracted through drinking water contaminated with water fleas (cyclops) infected with Dracunculus
  • Except for remote villages in Rajastan desert of India and Yemen the disease is now only seen in Africa, between the Sahara and Equator
  • Nigeria is one of the few countries with reports of >1,000 new cases a year
  • Efforts are currently going on to eradicate the disease in Nigeria

Pathophysiology

  • In the stomach, the larvae penetrate into the mesentery, where they mature sexually in 10 weeks
  • The female worm burrows to the cutaneous surface to deposit her larvae, causing specific skin manifestations
  • When the parasite comes in contact with water, the worm rapidly discharges its larvae, which are ingested by the cyclops

Clinical features

As the worm approaches the surface it may be felt as a cordlike thickening

It forms an indurated cutaneous papule

Several hours before the head appears at the skin surface there is (at the point of emergence)

  • Local erythema
  • Burning sensation
  • Pruritus
  • Tenderness

Soon after, the papule blisters and a painful ulcer develops, usually on the leg

  • Ulcer may occur on other parts of the body e.g. the genitalia, buttocks, or arms

Differential diagnoses

  • Sickle cell ulcer
  • Stasis ulcer

Complications

  • Secondary infection
  • Cellulitis
  • Erysipelas
  • Progressive lymphoedema
  • Oesteomyelitis
  • Arthritis
  • Tetanus

Investigations

Radiograph of the affected area

  • If osteomyelitis and arthritis (or calcified worms) are suspected

Treatment goals

  • Resolve local inflammation to permit easier removal of the worm
  • Extract the worm
  • Prevent and treat complications

Drug treatment

Metronidazole

Adult: 500 mg orally every 8 hours for 7 days

Child:7.5 mg/kg orally every 8 hours

Or:

Mebendazole

Adult: 400 - 800 mg orally daily for 6 days

Child over 1 year: usually 100 mg orally twice daily for 3 days

Or:

Ivermectin

Adult: 200 micrograms/kg orally as a single dose

Child. Consult specialist

Treat or prevent complications with antibiotics

Worm extraction

Traditionally:

  • Extract the worm slowly by winding it about a match stick or twig, removing 3 - 5 cm daily, with care not to rupture it
    • In the event of such an accident, the larvae escape into the tissues and produce fulminating inflammation
    • The process appears to be facilitated by placing the affected part in water several times a day

Notable adverse drug reactions, contraindications and caution

Metronidazole

  • Avoid high dose regimens in pregnancy
  • Avoid drinking alcohol during treatment and at least 48 hours after

Ivermectin

  • Oedema (face and limbs)
  • Fever, pruritus, lymphadenitis, malaise, hypotension
  • Should not be used in the presence of concurrents, loa infection: risk of encephalopatic reactions to dying loa loa microfilariae

Should not be used in patients with central nervous system diseases (e.g. meningitis): increased penetration of ivermectin into the CNS

Caution in early pregnancy

Prevention

  • Provide universal access to safe and portable water In hyperendemic areas, treat the whole population twice yearly with ivermectin