ISSN 2398-2985      

Fly strike

Jreptile

Synonym(s): Myiasis, Blow strike, Maggot infestation, Cuterebriasis


Introduction

  • Cause: fly larvae causing tissue damage. In the UK it is commonly caused by Lucilia spp (greenbottle fly) and in the USA Wohlfahrtia vigil, the flesh fly. Cuterebra spp can also cause myiasis. In reptiles, maggots of botflies, Phormia spp, Lucilia spp, Calliphora spp and Cistudinomyia cistudinis can cause myiasis.
  • Signs: depression, collapse, presence of fly larvae, open wounds, death.
  • Diagnosis: observation of fly larvae/maggots.
  • Treatment: fluid therapy, analgesia, supportive care, remove maggots, flush wounds, systemic antibiosis, address underlying causes.
  • Prognosis: depends on the severity; good if treated very early on.

Pathogenesis

Etiology

  • Fly larvae causing tissue damage. In the UK it is commonly caused by Lucilia spp (greenbottle fly) and in the USA Wohlfahrtia vigil, the flesh fly. Cuterebra spp can also cause myiasis.
  • Pharyngeal myiasis with flesh fly larvae has been reported in two lizards (common ameivas) (rare).
  • Maggots of botflies, Phormia spp, Lucilia spp, Calliphora spp and Cistudinomyia cistudinis can cause myiasis.

Predisposing factors

General

  • Warm, humid weather.
  • Animals kept outdoors in suboptimal conditions and health.
  • Unobserved/untreated diarrhea or excessive fecal soiling.
  • Wounds/broken skin Traumatic injuries.
  • Prolapse of tissues through vent aperture.
  • Hatching reptiles with exposed unabsorbed yolk sac.

Specific

  • Environmental conditions of at least 60% humidity and 9-11°C/48.2-51.8°F for fly larva development.

Pathophysiology

Myiasis by Lucilia spp

  • Flies lay eggs in open wounds or soiled skin/fur.
  • Eggs → L1 larvae. L1 maggots do not cause tissue damage.
  • L1 larvae → L2 → L3.
  • Larvae bury deeper into tissues.
  • Extensive tissue damage, secondary infections, and potentially fatal toxin release.

Myiasis by Cuterebra flies

  • Flies lay eggs on skin.
  • Developing larvae migrate through subcutaneous tissues or enter the subcutis through body openings.
  • Subdermal cysts seen with breathing hole caused by botfly.
  • Larvae 1-3 cm in length can be visualized within the lesion.

Timecourse

Myiasis by Lucilia spp

  • Eggs → L1 larvae (within 12 h). These are not harmful.
  • L1 larvae → L2 → L3 (within 3 days).

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Mitchell M A & Diaz-Figueroa O (2004) Wound management in reptiles. Vet Clin Exot Anim (1), 123-140 PubMed.
  • Harkewicz K A (2001) Dermatology of reptiles: A clinical approach to diagnosis and treatment. Vet Clin Exot Anim (2), 441-461 PubMed.

Other sources of information

  • Carpenter J W, Klaphake E, Gibbons P M & Sladky K K (2019) Reptile Formulary. In: Mader’s Reptile and Amphibian Medicine and Surgery. 3rd edn. Eds: Divers S J & Stahl S J. Elsevier, USA. pp 1191-1211.
  • Eatwell K & Hedley J (2019) Parasitology. In: BSAVA Manual of Reptiles. 3rd edn. Eds: Girling S J & Raiti P. BSAVA, UK. pp 411-422.
  • Fraser M A & Girling S J (2019) Dermatology. In: BSAVA Manual of Reptiles. 3rd edn. Eds: Girling S J & Raiti P. BSAVA, UK. pp 257-272.
  • Kischinovsky M, Divers S J, Wendland L D & Brown M B (2019) Otorhinolaryngology. In: Mader’s Reptile and Amphibian Medicine and Surgery. 3rd edn. Eds: Divers S J & Stahl S J. Elsevier, USA. pp 736-751.
  • Wright K & Raiti P (2019) Breeding and Neonatal Care. In: BSAVA Manual of Reptiles. 3rd edn. Eds: Girling S J & Raiti P. BSAVA, UK. pp 70-88.

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