Exotic Diseases

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Species Affected

can infest any warm-blooded animal

• found in tropical areas: Asia, Papua New Guinea, Africa, Americas

Aetiology

• Cochliomyia hominivoras - Americas
• Chrysomyia bezziana - Africa, Asia, Papua New Guinea

Epidemiology

• hot, humid weather essential for fly development, no dormant phase
• obligatory parasite
• eggs laid in fresh wounds only - bad seasons even mild wounds such as insect bites, excoriations, blowfly strike, umbilicus of newborn or on perineum soiled by recent birth discharges
• eggs hatch in 12 hours
• larvae in wound up to 7 days
• pupate in ground
• female flies mate only once
• basis of U.S. eradication programme using the release of cobalt irradiated sterile males

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Clinical Signs and Lesions


• larvae vigorously and deeply invade tissue (cf. other fly larvae)
• often only posterior spiracles of larvae visible in wound
• tissue damage extensive
• foul smelling exudate which attracts further flies
• affected animals wander restlessly
• if untreated death of animal likely; heavy losses possible if livestock infrequently inspected
• wounds heal rapidly following treatment

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Differential Diagnoses

     1.  any cause of myiasis - screw worm causes deeper lesions
     2.  equine phycomycosis
     3.  warble fly infestation