Myiasis

Background

Myiasis in patient neck

• Caused by Diptera species. Dermatobia hominis (botfly) is most common cause in North America
• Cutaneous (includes follicular, wound, and migratory) type is most common
  • Can also occur in mouth, urogenital, ophthalmic, nasopharyngeal location
• Typically occurs in tropical and subtropical areas. US cases typically due to travel to endemic region
• Bacterial superinfection is rare

Clinical Features

• Erythematous papule with central pore (allows for larval respiration)
• Sensation of movement within lesion
• Serous drainage

Differential Diagnosis

Travel Related Skin Conditions

Papules

• Insect bites
• Scabies
• Seabather's eruption
• Cercarial dermatitis (Swimmer's Itch)

Sub Q Swelling and Nodules

• Myiasis
• Tungiasis
• Loa loa
• African Trypanosomiasis
• Onchocerciasis

Ulcers

• Pyoderma
• Leishmaniasis
• Mycobacterium marinum

Linear and Migratory Lesions

• Cutaneous Larvae Migrans
• Photodermatitis

Ectoparasites

• Bed bugs
• Lice
• Myiasis
• Scabies
• Ticks

Evaluation

• Clinical diagnosis

Management

If entire larvae is not removed, severe inflammatory response occurs

• Occlusion of central pore with petroleum jelly or mineral oil interrupts oxygen supply and causes larvae to migrate to surface where it can be grasped with forceps and removed
  • Can take up to 24 hours
• Manual removal by squeezing out larvae
• Surgical removal by making incision over larvae and removing with forceps
• Ivermectin - single PO dose or topical application
• Wound myiasis requires surgical debridement
• Ocular, nasopharyngeal, urogenital myiasis should prompt appropriate specialist consultation for management

Disposition

• Cutaneous myiasis generally may be discharged after removal
• Disposition of other forms based on discussion with specialist

See Also

• Parasitic Diseases
• Travel Medicine

References

Authors

Michael Holtz, Ross Donaldson, Neil Young, Daniel Ostermayer