Myiasis Producing Flies


Introduction

Myiasis is the parasitism of living animals by dipteran larvae. Myiasis can be obligatory or facultative (optional) and is described as cutaneous, nasal or somatic.

Oestridae

Dermatobia hominis

Calliphoridae




Screw Worm Myiasis

Screw worm larvae - John Kucharski - Wikimedia Commons
  • C. bezziana cause myiasis in both animals and humans
  • Located mainly in tropical regions
  • Larvae are obligate parasites


Recognition

  • Similar to Calliphora spp.
    • Iridescent
    • Clear wings
    • Blue abdomen
  • Longitudinal stripes on thorax
  • Larvae have bands of spines
    • Look like screws


Life cycle

  • Eggs laid in wounds or body cavities
  • Larvae feed as colonies
  • Larvae drop to the ground to pupate


Pathogenesis

  • Spiracles are exposed as larvae feed which expands the wound
    • Creates a foul smelling lesion
  • Cause irritation and pyrexia


Control

  • In the USA
    • Mass eradication through the release of sterile males
    • Currently only persists where flies have migrated across the Mexican border
  • In Africa
    • Introduced into Libya through the importation of infested livestock
    • Sterile males released
    • Eradication occurred in 1991


Maggot Debridement Therapy

Maggot therapy on a wound - Wikimedia Commons
  • Human medicine
    • Sterile Lucilia sericata maggots used to treat infected and necrotic wounds
    • Larvae secrete proteolytic enzymes and antimicrobial agents into the wound
    • Larvae do not burrow under the skin or attack healthy tissue
  • Veterinary medicine
    • Published reports rare
    • Recently used successfully to treat a suppurative wound in a donkey that did not respond to conventional medical methods and surgery


Wohlfahrtia spp.

  • Obligatory parasite
  • Occurs in North America
  • Parasite of mink and sometimes humans


Recognition

  • Large 8-14mm long
  • Pale grey
  • Black stripes on thorax
  • Black spots on abdomen


Life cycle

  • Larvae deposited directly onto host
  • No egg stage
  • Larvae moult twice on host then fall to ground to pupate


Pathogenesis

  • Larvae penetrate intact skin
    • Cause boil like swellings

Myiasis Producing Flies Flashcards

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