Myiasis is the invasion of organs and tissues of humans or other vertebrateanimals by fly larvae, which at least for some time feed on the living or dead tissuesor, in the case of intestinal myiasis, on the host’s ingested food.

Types of myiasis

Myiasis may be accidental, obligatory or facultative.

Accidental myiasis usually involves eating foodthat is contaminated by eggs or larvae of flies that are not parasitic inmammals, such as house flies. Although the larvae may survive for some time inthe intestine, no flies are specially adapted to cause intestinal myiasis inhumans. (In contrast, obligatory intestinal myiasis occurs in other mammals.)The presence of larvae in the human intestine may nevertheless causeconsiderable discomfort, abdominal pain and diarrhoea, which may be accompaniedby discharge of blood and vomiting. Living larvae may be passed in excreta orvomit.

In obligatory myiasis it is essential for the flymaggots (larvae) to live on a live hostfor at least a part of their life. For example, larvae of Cordylobiaanthropophaga, Cochliomyia hominivorax, Chrysomya bezziana, Dermatobiahominis and Wohlfahrtia magnifica are allobligatory parasites of humans and other vertebrates.