Myiasis

Definition

Myiasis is the infection of a fly larva (maggot) in human tissue. The infection of a fly larva (maggot) in human tissue, which most commonly occurs in tropical climates. Affected tissues most commonly include skin, especially if open wounds are present, nasal passages, ears, and eyes.

Epidemiology

Myiasis occurs in tropical and subtropical areas. These can include countries in Central America, South America, Africa, and the Caribbean Islands.

Cause

• Myiasis is infection with the larval stage (maggots) of various flies.
• Flies in several genera may cause myiasis in humans.
• Dermatobia hominis is the primary human bot fly.
• Cochliomyia hominovorax is the primary screwworm fly in the New World and Chrysomya bezziana is the Old World screwworm.
• Cordylobia anthropophaga is known as the tumbu fly.
• Flies in the genera Cuterebra, Oestrus and Wohlfahrtia are animal parasites that also occasionally infect humans.

Tranmission

There are several ways for flies to transmit their larvae to people.

• Some flies deposit their eggs on or near a wound or sore, the larvae that hatch burrow into the skin. Certain species’ larvae will move deeper in the body and cause severe damage.
• Some flies attach their eggs to mosquitoes, other flies or ticks and wait for those insects to bite people. Their larvae then enter these bites.
• One type of fly found in Africa lays its eggs on the ground or on damp cloth such as clothing or bed linens that are hung out to dry. The larvae hatch from the eggs and people get infected by contact with the ground or clothes that have fly larvae attached to them.

Signs and symptoms

• A lump will develop in tissue as the larva grows.
• Larvae under the skin may move on occasion.
• Usually larvae will remain under the skin and not travel throughout the body.

Diagnosis

• Clues that myiasis may be present include recent travel to an endemic area, one or more non-healing lesions on the skin, itchiness, movement under the skin or pain, discharge from a central punctum (tiny hole), or a small, white structure protruding from the lesion.
• Serologic testing has also been used to diagnose the presence of botfly larvae in human ophthalmomyiasis.

Treatment

• Fly larvae need to be surgically removed.
• No medications approved by the FDA are available for treatment.
• Preventing possible exposure is key advice for patients traveling in tropical areas of Africa and South America.
• Those with untreated and open wounds are more at risk.

Prevention

• Take extra care going to tropical areas and spending a lot of time outside.
• Cover your skin to limit the area open to bites from flies, mosquitoes, and ticks.
• Use insect repellant and follow Travelers Health guidelines.
• In areas where myiasis is known to occur, protect yourself by using window screens and mosquito nets.
• In tropical areas, iron any clothes that were put on the line to dry.

Spread

No. Myiasis is not spread from person to person. The only way to get myiasis is through flies, ticks, and mosquitoes.

NIH genetic and rare disease info

• NIH info on Myiasis

Myiasis is a rare disease.

Myiasis Resources
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