Botfly Myiasis: How Larvae Infest Human Skin in the Tropics

Cutaneous myiasis by Dermatobia hominis (human botfly) occurs in tropical/subtropical Americas. The adult fly deposits eggs on blood-feeding arthropods (mosquitoes, ticks); when the vector bites a human, warmth triggers larval hatching and penetration.

Lifecycle & Clinical Course

1. Larva enters skin → forms furuncle-like lesion with central pore (breathing hole).
2. Grows for 6-10 weeks, feeding on tissue exudate.
3. Mature larva (1.5-2 cm) exits spontaneously or is extracted.
4. Lesion heals, often with minimal scarring.

Symptoms

• Pruritic, painful nodule; intermittent movement sensation.
• Serosanguinous discharge from pore.
• Secondary bacterial infection possible.

Removal Techniques

• Occlusion: Petroleum jelly, nail polish, or adhesive tape over pore → larva asphyxiates, emerges for air.
• Manual extraction: Gentle traction with forceps after local anesthesia; avoid rupture.
• Surgical: Incision if deeply embedded or inflamed.
• Ivermectin: Oral (200 µg/kg) may kill larva; used for multiple lesions.

Prevention

• Insect repellent (DEET, picaridin), permethrin-treated clothing.
• Bed nets, window screens.
• Avoid vector habitats at peak biting times.

Travelers to endemic areas should recognize the characteristic breathing pore for early removal.