Myiasis

Myiasis

Dermatobia larva, ca. 1cm long

Infestation of skin by fly larvae, which feed on living or dead tissue

There are three main variants of this condition: cutaneous, body cavity and accidental myiasis

1   Cutaneous myiasis

  • bloodsucking, in which larvae attach to the skin and either bite or suck blood: Auchmeromyia, Tabanidae, Therevidae
  • furuncular, in which larvae penetrate skin to make boil-like lesions: Cordylobia, Dermatobia, Wohlfartia
  • creeping, in which larvae tunnel in the epidermis without completing their life cycle: Hypodermatinae, Gasterophilinae
  • wound/traumatic, in which larvae develop in wounds: Calliphoridae, Fanniidae, Muscidae, Phoridae, Sarcophagidae

2   Body cavity myiasis

  • nasopharyngeal, lung, auricular & ophthalmomyiasis in which eggs or larvae deposited in cavities: Calliphoridae, Oestridae, Phoridae, Sarcophagidae

3   Accidental myiasis

  • intestinal, in which larvae ingested or enter via rectum: Anisopodidae, Calliphoridae, Drosophilidae, Fanniidae, Muscidae & others
  • urogenital in which adults attracted to infected tissue or clothing: Anisopodidae, Calliporidae, Fanniidae, Muscidae and others

Larva of Dermatobia hominis, the cause of furuncular cutaneous myiasis in man, cattle, dogs, other mammals and some birds in Central and South America.

D. hominis is occasionally seen in international travellers from outside the region. Dermatobia belongs to the Cuterebrinae sub-family of the Oestridae family of Diptera. Their larvae have bodies with strong, evenly distributed spines and posterior spiracles with a lot of small, serpentine slits.

A small nodule with a central breathing pore develops around the larva at the site of penetration. These swelling usually last for a few weeks, before the mature larva emerges and drops to the ground to pupate.

Reference:

Hall MJR, Smith KGV. Diptera causing myiasis in man. Ch 12. ed Lane RP, Crosskey RW. Medical Insects & Arachnids. Chapman & Hall, London, 1993. ISBN 0 412 40000 6.

Micrognome, October, 2011

 

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