Myiasis

• Infection by dipterous flies in moist body areas (eg. perineum)
• Commonly affects sheep - ovine fleece rot
• Grossly:
  • Matted hair or wool, may be in wounds
  • Multiple holes or ulcers
  • Malodour
• May result in death due to septicaemia or toxaemia
• Cuterebra myiasis
  • Caused by Cuterebra sp
  • Young animals come into contact with eggs on stones or plants
  • Nodules with larvae in subcutis + respiration openings to surface
• Hypoderma myiasis
  • Caused by Hypoderma lineatum or H. bovis
  • Mainly affects cattle
  • Skin of legs is penetrated -> migration through oesophagus or vertebral canal to subcutis of back
  • Cause subcutaneous nodules with respiration openings
  • Larvae in cavity with fibrin and eosinophils surrounded by granulation tissue with eosinophil clusters
• Screwworm myiasis
  • Occurs in Africa, Asia, Central and South America
  • Larvaae are deposited in wounds
  • Penetrate and liquify tissue