Human ophthalmomyiasis interna caused by Hypoderma tarandi, Northern Canada

Abstract

Human myiasis caused by bot flies of nonhuman animals is rare but may be increasing. The treatment of choice is laser photocoagulation or vitrectomy with larva removal and intraocular steroids. Ophthalmomyiasis caused by Hypoderma spp. should be recognized as a potentially reversible cause of vision loss.

Figure 1

A) Retinal hemorrhages visible on funduscopic examination of right eye of a 41-year-old woman, Nunavut, Canada, with ophthalmomyiasis intern). B) Segmented 3-mm larva with a cylindrical body, no visible spines, and indistinguishable anterior and posterior ends in the vitreous cavity, corresponding to the first instar of Hypoderma tarandi.

Figure 2

Scanning electron microscope images of the parasite from an 11-year-old Inuit boy, Nunavut, Canada. A) Anterior end of the maggot. The cephalic segment is evident; mouth and mouth hooks are present (boxed). Scale bar = 50 μm. B) The characteristic cephalic sensory array (boxed). Scale bar = 10 μm. C) Posterior segments of the maggot. Scale bar = 100 μm. D) Spiracular openings on the posterior segments of the maggot characteristic of first instar of Hypoderma. Scale bar = 10 μm.