(flesh fly or sarcophagids)Flesh flies, or sarcophagids, members of the family Sarcophagidae, can cause intestinal myiasis in humans if the females lay their eggs on meat or fruit. Accidental myiasis
Also called pseudomyiasis. Caused by flies that have no preference or need to develop in a host but that will do so on rare occasions. Transmission occurs through accidental deposit of eggs on oral or genitourinary openings, or by swallowing eggs or larvae that are on food. The cheese fly (Piophila casei) sometimes causes myiasis through intentional consumption of its maggots (which are contained in the traditional Sardinian delicacy casu marzu). Other flies that can accidentally cause myiasis are:
Musca domestica (housefly)
Fannia spp. (latrine flies)
Eristalis tenax (rat-tailed maggots)
Muscina spp.The adult flies are not parasitic, but when they lay their eggs in open wounds and these hatch into their larval stage (also known as maggots or grubs), the larvae feed on live or necrotic tissue, causing myiasis to develop. They may also be ingested or enter through other body apertures. Diagnosis
Myiasis is often misdiagnosed in the United States because it is rare and its symptoms are not specific. Intestinal myiasis and urinary myiasis are especially difficult to diagnose.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.
Secondly the wound must be cleaned and disinfected. Further control is necessary to avoid further reinfestation.Livestock may be treated prophylactically with slow-release boluses containing ivermectin, which can provide long-term protection against the development of the larvae. Sheep also may be dipped, a process which involves drenching the animals in persistent insecticide to poison the larvae before they develop into a problem. Epidemiology
The most common infected animal worldwide is the domestic sheep, for more information see fly strike in sheep. This condition is caused by the blowfly (particularly Lucilia sericata and its sister species L. cuprina), especially where the weather is often hot and wet. Blowfly strike accounts for over A$170 million a year in losses in the Australian sheep industry, the largest such losses in the world. Given the seriousness of the risk, Australian sheep farmers commonly perform preventive measures such as mulesing designed to remove the most common targets for the flies. The docking of lambs tails (another frequently-soiled area that flies target) is also commonly practiced by sheep farmers worldwide. Maggots also occasionally infest the vulvar area, causing the condition called vulvar myiasis. Such problems are not peculiar to Australia and New Zealand; they occur worldwide, especially in countries where livestock, particularly sheep, are kept under hot, wet, conditions, including most of Africa and the Americas, ranging from the cold temperate regions in the north, to corresponding latitudes in the south.