Myiasis is the invasion of living tissue or organs of vertebrates by larvae of fly (maggot). Feeding activity of the larvae may cause serious tissue damage, often accompanied by putrid discharge and ulceration, resulting in loss of function, injury to the skin, secondary bacterial invasion and death.
Chrysomya bezziana, the Old World Screw-worm Fly, is an obligate parasite of mammals. The site of infection is usually at superficial wounds. Adult fly feeds on decomposing corpses, decaying matter, excreta and flowers. Adult female only lays eggs on live mammals, depositing approximately 200 eggs at sites of wounding or in body orifices such as the ear and nose. Wounds in the size of a tick bite are sufficient to attract egg-laying.
The eggs hatch in 24 hours and the resulting larvae burrow into the host’s tissues and feed on the host’s dead or living tissue. The larvae are unable to develop in carrion. They leave the wound after 5-7 days and fall to the ground to pupate. Under hot and humid weather, they can complete the life cycle within 15-30 days. Adult flies live on average for 2-3 weeks.
Chrysomya bezziana is an agent of myiasis: the infestation of live vertebrate animals with larvae, which, at least for a certain period, feed on the host’s dead or living tissue. Feeding activity of the larvae may cause serious tissue damage, resulting in loss of condition, injury to the skin/hide, secondary invasion and death. Same as other members of this genus, Chrysomya bezziana adults commonly visit faeces and decaying matters. Because of this habit, they, therefore, are mechanical carriers of pathogens.