Human Bot Fly Infestation of the Eyelid
This 68-year-old healthy male presented for evaluation of a hordeolum of the left lower eyelid (Fig. 1A). Four weeks earlier, he returned from a 2-week trip to Belize and subsequently noted progressive enlargement of an eyelid nodule. A culture grew methicillin-resistant Staphylococcus aureus, but the lesion increased despite antibiotics. On presentation, a firm, minimally tender lesion with a central pore was evident, which on slit lamp examination revealed a mobile organism (Fig. 1B). Infectious disease consultants suspected bot fly larva and recommended excision, which was performed, as demonstrated in the video (Video, Supplemental Digital Content 1, available at http://links.lww.com/IOP/A147). The central pore was enlarged using Westcott scissors to create a small subciliary incision. A chalazion clamp was placed, the larva was grasped with forceps, and the chalazion clamp was gradually tightened allowing the larva to be eased out of the eyelid (Fig. 2). The laboratory confirmed Dermatobia hominis (human bot fly). The patient continued oral doxycycline to prevent superinfection and his eyelid healed well.
The adult female bot fly deposits eggs on a carrier insect such as a mosquito, and the eggs are transferred to the host animal or human with the mosquito bite. The eggs hatch and the larvae burrow into the host’s skin. A raised, erythematous skin lesion results. The larva matures over 4–10 weeks, then drops into the soil and pupates. The lesion in the host resolves spontaneously unless superinfected. Bot flies are present in Central and South America but not the United States.