Dracunculus

• Dracunculus medinensis

  Guinea Worm
• It is biblical
• Common Name

  Guinea Worm
• Expected by CDC to eradicate next after smallpox
• Only eradicated infectious disease worldwide is the smallpox
• Eradication


  No more native infection, no more transmission from human to human or animals to human
• The DNA of smallpox are actually preserved in Russia
• Dracunculus medinensis

  • Longest nematode known to cause human parasitism
  • A. Lumbricoides is the biggest and D. Medinensis the longest
• Serpent of the Nile


  Dracunculus medinensis
• Epidemiology

  • Predominant in Africa, India, Pakistan, Saudi Arabia, Yemen
• Transmission

  Can be transmitted living near freshwater lakes and rivers
• Definitive Hosts

  • Humans, wolves, dogs, horses, cows, leopards, monkeys, baboons
• Intermediate Host

  Cyclops copepods
• Infective Stage

  Third stage larva (L3) within the cyclops copepods
• Diagnostic Stage

  Female adult worm in the subcutaneous tissue, rhabditiform larvae
• Adult male dies after copulation
• Length

  • Female: 60 cm up to 3 ft
  • Male: 1.2 – 2.9 cm
  • Larvae: 500-700 um
• Cyclops Copepods

  The worm inside the body is the D. Medinensis larva. L3 larva that is infective to humans and other definitive host
• How humans acquire the parasite

  1. Direct digestion of the L3 together which are actually house the copepods cyclops

  2. Eating the other host that might harbor this copepods cyclops which has L3 larvae

  3. Larvae are released when the copepods cyclops die inside the stomach

  4. Larvae penetrate the stomach or the intestinal wall and undergo molting

  5. Male and female copulate, male dies, female migrates to lower extremities

  6. Female releases chemical that elicits immune response, causing blister formation and release of rhabditiform larva

  7. Rhabditiform larva eaten by copepods cyclops, develop into L3 larva
• The female D. Medinensis the release of rhabditiform larva is triggered by exposure from the water
• Drinking water from the river can infect humans with D. Medinensis
• Paratenic host (fish) might ingest the L3 within the copepods cyclops then be eaten by person either raw or improperly cooked
• Diagnostic Stage

  L1 or rhabditiform larva, or visualisation of the adult worm
• Pathogenesis and Clinical Manifestations

  1. Female adult worm releases toxic chemical, causing nausea, rash, diarrhea, dizziness, localized edema, reddish papule, blister, and itching

  2. Worm fails to reach the skin, gets calcified in the joint causing arthritis

  3. Worm reaches CNS (spine or brain) causing paraplegia

  4. Abscess and swelling when the worms rupture, eliciting heightened inflammatory response

  5. Secondary bacterial infection on blisters or ulcers

  6. Entry of tetanus spores with the retreating worm
• Bacterial super infection can occur
• If the parasite is improperly recovered, the adult worm can disrupt and crawl back into the tissue
• The worm can harbor bacteria and carry tetanus spores
• Diagnosis

  Recovery of adult worm from the blister, recovery of rhabditiform larvae from fluid discharged by the worm
• How to recover the parasite

  Use a stick to slowly roll out the entire worm over several days
• Diagnostic images

  • X-ray showing opaque parasite, surgical intervention to remove disrupted parasite
• Treatment


  1. Manual removal of adult female worm by submerging affected area in water, applying gentle pressure to slowly extract the worm

  2. Use of epinephrine for severe allergic manifestations

  3. Use of anti-helminthic agents (less role)
• Prevention and Control

  • Patient education
  • Safe drinking practices, including filtration of drinking water