Myiasis

Introduction

Myiasis is the parasitic infestation of the body of a live animal by fly larvae (maggots) which grow inside the host while feeding on its tissue.

Furuncular myiasis may be caused by:

• Dermatobia hominisor
• the Tumbu fly
• Cordylobia anthropophaga

Larvae of Dermatobia hominis are often transferred by mosquitoes.

Usual host of this larva is cattle.
People living near cattle rearing areas are particularly vulnerable.

Eggs, living larvae, or both are deposited on the skin or mucous membranes or on clothing.

Eggs hatch and produce larvae that then
burrow into the skin and cause mild or
severe inflammatory changes

Symptoms and Clinical features of Myiasis

1. Furuncular myiasis looks like a furuncle (boil)
2. Key feature is the presence of a tiny hole in the inflammed erythematous papule
3. There may be a sensation of motion within the furuncle
4. There may be intermittent stinging sensation
5. In accidental myiasis, there is a pre existing lesion, usually a leg ulcer, wound or ulcerated basal cell carcinoma

Differential diagnoses

• Furuncles and carbuncles

Complications of Myiasis

• Secondary bacterial infection

Investigation

• Nil

Treatment for Myiasis

Treatment objectives

1. Extract the maggot
2. Treat or prevent bacterial infection

Non-drug treatment

• Apply petrolatum: the maggot crawls out to avoid asphyxiation

Or:

• Extract the maggot by compressing
  simultaneously from beneath on both sides with a pair of spatulae

Drug treatment

• Prevent bacterial infection with oral antibiotics if lesions are multiple
• Wound myiasis is flushed out surgically with antiseptics: surgical debridement

Prevention of Myiasis

Iron clothes that are dried in the open air