Oestridae Causing Myiasis

Due to their habit of feeding on live tissues, larvae of the family Oestridae are known as causative agents of obligatory myases of many animal species, including humans. This group of flies includes a large number of species, about 150, ranked in four sub-families which cause internal organ myases with formation of subcutaneous warbles (Hypodermatinae) or infestations in the digestive tract (Gasterophilinae), nasal or pharyngeal cavities (Oestrinae) or dermis (Cuterebrinae). Oestrids evolved a high degree of host specificity with complex biological life cycles and strict interaction with the host immune system. Oestrids may impair livestock productions through adult fly disturbance of grazing animals (e.g. reduction in weight gain and milk production), or larval direct damage in infested organs (e.g. ulcers in the mouth and nasal cavities or in the digestive tract), allergic reactions and even death of animals in severe cases. Humans may be occasionally infested with skin, ocular and internal organs myases. For some myiases, such as cattle hypodermoses, migrating larvae elicit both cellular and antibody responsiveness in the host and early serological detection of specific antibodies have allowed the validation of diagnostic tools supporting the decision of treating infested animals. Consequently, the systemic use of macrocyclic lactones has greatly reduced the overall burden of these myases, though they still remain a problem in livestock in many parts of the world. In this chapter, we summarize the epidemiology, life cycle, the medical and veterinary importance as well as the control of the main species belonging to the family Oestridae.