Furuncular myiasis is a skin infestation caused by the larvae (maggots) of certain fly species, primarily Dermatobia hominis (the human botfly) and Cordylobia anthropophaga (the African tumbu fly), that results in boil-like lesions on the skin.
Understanding Furuncular Myiasis
Myiasis, in general, refers to the infestation of a living vertebrate animal by fly larvae that feed on the host's dead or living tissue, body fluids, or ingested substances. Furuncular myiasis is a specific type where the larvae burrow into the skin, creating painful, boil-like sores that are often mistaken for common furuncles (boils).
Causative Agents:
-
Dermatobia hominis (Human Botfly): The female botfly doesn't directly lay eggs on a human host. Instead, it captures other insects, like mosquitoes or ticks, and attaches its eggs to them. When these insects land on a human to feed, the warmth triggers the botfly larvae to hatch and burrow into the skin.
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Cordylobia anthropophaga (Tumbu Fly): This fly lays its eggs on the ground or on damp clothing left outside. The larvae hatch and can penetrate the skin of a host that comes into contact with the contaminated surface.
Symptoms:
- Boil-like lesions: The primary symptom is the appearance of one or more painful, raised, boil-like lesions on the skin.
- Central punctum: Each lesion usually has a small opening (punctum) at the center, through which the larva breathes.
- Serosanguinous drainage: A clear or blood-tinged fluid may drain from the lesion.
- Itching and pain: The area around the lesion is often itchy and painful.
- Movement sensation: Some individuals may feel the larva moving within the lesion.
Diagnosis:
Diagnosis is typically based on clinical presentation (the appearance of the lesion) and a history of travel to or residence in regions where these flies are prevalent (Central and South America for D. hominis, and Africa for C. anthropophaga). Sometimes, the larva can be visualized through the punctum.
Treatment:
The most effective treatment involves removing the larva. This can be done by:
- Surgical excision: A small incision can be made to extract the larva.
- Occlusion: Applying a thick ointment or tape over the punctum to cut off the larva's air supply, forcing it to emerge.
- Larva extraction: Once the larva comes closer to the surface (induced by methods like occlusion), it can be carefully removed using forceps.
- Antibiotics: Antibiotics are generally not necessary unless there is a secondary bacterial infection.
Prevention:
- Avoid insect bites: Use insect repellent containing DEET.
- Wear protective clothing: When in endemic areas, wear long sleeves and pants.
- Iron clothes: Ironing clothes, particularly those that have been dried outside, can kill any eggs that may be present.
