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Myiasis
Myiasis is the infestation of the organs or tissues of host animals by the larval stage dipterous flies, usually known as maggots or grubs. The fly larvae feed directly on the host'snecrotic or living tissue. The hosts are usually mammals, occasionally birds and, less commonly, amphibians or reptiles
In cutaneous myiasis, the two main clinical types are wound myiasis and furuncular (follicular) myiasis. Other forms include creeping/migratory myiasis and cavitary myiasis of body organs. In nasopharyngeal myiasis, the nose, sinuses, and pharynx are involved.
Larvicides
Ivermectin is a broad-spectrum antiparasitic agent that may kill larvae, or at least cause them to migrate out of the skin. ...
Mineral turpentine can be effective against Chrysomya larvae and may aid their removal in cases of wound myiasis.
Myiases (Greek MYIA = fly) are infestations of humans and animals with maggot larvae of flies, which feed on dead or living host tissue for a variable period
Classification is based on their location on the host body (dermal, subdermal, nasopharyngeal, internal organs, intestinal and urogenital) or, in parasitological terms, according to the type of hostparasite relationship (obligatory, facultative or pseudomyiases)
Cause: maggot larvae of flies of the orderDiptera
Signs: fly strike occurs mostly in warm weather, and is usually preceded by soiling or moist dermatitis. Fly larvae cause alopecia and erosion/ulceration and may enter body cavities. Secondary skin infection is common and peritonitis/septicemia may be associated with entry to the body cavity.
Diagnosis: clinical signs
Treatment: clip and clean area, remove maggots, antibiotics, fluid therapy
Prognosis: poor in severe cases, otherwise dependant on predisposing conditions
Pathogenesis
Etiology
Dipterafly larvae, especiallyLucilia sericataand other Calliphora species
The Old World Screwworm fly (Chrysomya bezziana) has recently been causing aggressive myiasis in pet dogs in Hong Kong. Cochliomyia hominovoraxis still reported in the US
Predisposing factors
General
Some maggots (egCalliphorids)are only present on dead tissues.
Some maggots (egSarcophagids) only attack living tissue.
Draining wounds or urine soaked coats.
diseases, especially those causing diarrhea and soiling of the perineum or a decrease in grooming activity.
Obesity.
Warm weather.
Unattended wounds.
Poor hygiene/lack of adequate observation of pet.
Pathophysiology
Laying of Diptera eggs on unattended wounds.
Maggots damage skin and burrow under skin.
As skin breaks down and liquefies it becomes more suitable for further infestation.
Body cavities may be entered leading to peritonitis Peritonitis /septicemia .
Some larvae (egCuterebra) can penetrate intact skin and produce nodular lesions. Eggs are deposited on vegetation and animals become infested as they pass through contaminated areas. As dogs and cats are abnormal hosts the larvae undergo aberrant migrations. In the late fall the larvae enlarge producing a swelling and a fistula develops
Time course
Can be very rapid (hours) - some fly species are viviparous and deposit live maggots directly onto the skin. In ideal conditions even eggs will hatch within 8 hours
Blowflies (Calliphoridae) and fleshflies (Sarcophagidae) cause myiases of relratively short duration, by both obligate and/or facultative parasites, which mature within 47 days, usually at the host's body orifices and in wounds (Cochliomyia hominivorax, andChrysomya bezziana)
Botflies (Oestridae) are obligate parasites that are harbored and feed for several weeks to months in the host's nasopharyngeal tract
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