Can myiasis occur in the skin in any location?

Myiasis Can Occur in Skin at Any Location

Yes, fly larvae can infest the skin in virtually any anatomical location, with cutaneous myiasis representing a parasitic infestation that occurs worldwide but is most common in tropical and subtropical regions. 1, 2

Types of Cutaneous Myiasis

Cutaneous myiasis manifests in three distinct clinical patterns, each with different characteristics:

Furuncular (Localized) Myiasis

• Most common presentation in travelers returning from endemic areas, appearing as abscess-like lesions that develop at the site of larval penetration 1, 2
• In Central and South America, primarily caused by the botfly (Dermatobia hominis), which uses a unique transmission mechanism where eggs are deposited on blood-sucking arthropods (usually mosquitoes) that then transfer larvae to human skin 1
• In Africa, the tumbu fly (Cordylobia anthropophaga) is the predominant cause, with infection occurring after direct contact with eggs deposited on clothing or towels 1
• Patients characteristically report creeping sensations of movement under the skin, which is a key diagnostic clue 1
• Can occur anywhere on the body but commonly affects exposed areas 3

Migratory Myiasis

• Larvae migrate through subcutaneous tissues creating linear or serpiginous tracks 2
• Less common than furuncular type but can affect any skin location 2

Wound Myiasis

• Occurs when fly larvae infest open wounds, regardless of body location 2
• More common in patients with predisposing factors including chronic wounds, mental deficit, alcohol/drug abuse, sleeping outdoors, prostration, and malnutrition 4

Geographic Distribution and Risk Factors

The burden of myiasis is significantly heavier in tropical and subtropical countries, though cases occur worldwide across all five continents 2, 4

Key risk factors include:

• Travel to endemic regions (Central/South America, Africa, tropical areas) 1, 2
• Outdoor activities near potential breeding sites 5
• Pre-existing skin conditions or open wounds 4
• Poor hygiene or inability to maintain personal care 4

Important caveat: Autochthonous (locally acquired) cases can occur even in temperate regions like Ohio, caused by the rodent botfly Cuterebra endemic to North America, where humans serve as incidental hosts 5

Clinical Presentation

The clinical picture varies by location but typically includes:

• Abscess-like nodules with central punctum (breathing hole for the larva) 1, 2
• Erythema, swelling, and intermittent pain at the affected site 4, 5
• Pathognomonic sensation of movement beneath the skin 1, 5
• Serous or serosanguinous discharge from the central opening 3
• Systemic symptoms (fever, malaise) may occur but are less common 4

Diagnostic Approach

Point-of-care ultrasound (POCUS) can rapidly confirm the diagnosis by visualizing the larva with characteristic spicules, distinguishing myiasis from common soft tissue infections like abscesses or cellulitis 5

Key diagnostic features to identify:

• History of travel to endemic areas or outdoor exposure 3, 5
• Slow-growing nodule following insect bite or outdoor activity 5
• Patient report of movement sensation under skin 1, 5
• Visualization of larva on ultrasound (appears as 2cm structure with spicules) 5

Common pitfall: Myiasis is frequently misdiagnosed as simple abscess or cellulitis, leading to inappropriate antibiotic therapy without larval removal 5

Treatment

The definitive treatment is complete mechanical extraction of the larva from the affected site—antibiotics alone are not curative 2, 3

Treatment algorithm:

1. Confirm diagnosis with ultrasound if available 5
2. Extract larva completely via small incision under local anesthesia 5
3. Clean and dress the wound appropriately 5
4. Antibiotics are only indicated for secondary bacterial superinfection, not for the myiasis itself 2
5. Ensure complete removal to prevent abscess formation and superinfection 1

Alternative extraction techniques (when surgical removal not immediately feasible):

• Occlusion of the breathing hole to force larva to surface
• However, surgical extraction remains the gold standard 3

Prevention

Understanding transmission modes is essential for prevention:

• For botfly myiasis: Use insect repellent to prevent mosquito bites that transmit larvae 1
• For tumbu fly: Iron all clothing and towels when in endemic areas, as heat kills eggs 1
• Avoid sleeping outdoors in endemic regions 4
• Maintain proper wound care for any open skin lesions 2

Following spontaneous hatching, healing typically occurs without intervention, though extraction is strongly recommended to prevent complications 1