1. Myiasis
Definition:
The invasion of organs and tissues of humans or other vertebrate animals with larvae of dipterous flies, which for a period, feed upon the living or dead tissue.
So, Myiasis is a medical term for infestation with the larvae (maggots) of a dipterous fly

2. Types of myiasis: Accidental Facultative Obligatory
Egg or larvae reach human food or drink accidentally
Insects in the family Muscidae
Facultative
Necrobiots but can feed on living tissue
Maggot therapy
Maggots free-living, attack carcasses, may attack living host.
Obligatory
Maggots live on a live host for part of their life.(obligatory sarcobiots)

3. Common Causes of Myiasis
The main flies that cause myiasis in humans and livestock belong to three main families: - Calliphoridae (blowflies) - Sarcophagidae (fleshflies) - Oestridae (botflies)

4. I- Calliphoridae (blowflies ): a- non-metallic flies
Cordylobia anthropophaga
Larvae Adult

5. Calliphoridae: b- Metallic Flies
Lucilia spp.
Cochliomyia
hominivorax

6. Cochliomyia hominivorax
The larvae have a pair of hooks near the mouth, which attach to the substrate while it feeds.

7. II- Sarcophagidae: Flesh-Flies
Sarcophaga spp.

8. III- Oestroiedae (Oestridae)
Dermatobia hominis

9. Medical importance:
Myiasis often results in considerable damage and disfigurement, especially if face is attacked.
When maggots invade nose, mouth, eyes they can cause severe pain. They may eat their way through the palate.
Offensive discharges and ulcerations.
Treatment should be immediate!

10. Maggot Therapy (Larval Therapy)
Maggot therapy is a widely accepted treatment for chronic, non-healing wounds. Used larvae feed mainly on pus & necrotic tissue.
The maggots are painless, effective and offer a safe way to perform debridement (removal of dead tissues) Removal of larvae is easy. Rarely invade healthy tissue.

11. Mechanism of Action
The larvae feed on dead tissue and cellular debris found in necrotic wounds, secrete proteolytic enzymes that liquefy the necrotic tissue, which, in turn, the larvae absorb and ingest.
The maggots also assist in killing bacteria through a number of mechanisms including bacteriocidal byproducts of the larval gut, and chemical secretions that change the pH of the wound bed. . So, useful in the treatment of severely infected wounds, for extremely debilitated or severely diabetic patients or who may not be candidates for surgical debridement procedures.
Some suggested that myiasis directly stimulates granulation tissue through physical stimulation or chemical mediators.