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Figure 1. A 46-year-old woman had an enlarging, tender, draining nodule on the upper arm. Prior treatment consisting of hot compresses and a course of oral antibiotics had had no effect. The patient had no other symptoms or findings, and the results of routine blood studies were normal. She had traveled to southern Mexico six weeks earlier for an archaeological dig. During her clinic visit, a human botfly larva (Dermatobia hominis) began to emerge from the nodule (Panel A). The traditional treatment in areas where myiasis is endemic (Mexico and South and Central America) is occlusion of the furuncular punctum with pork fat to stimulate extrusion of the larva. Neither the pork-fat treatment nor surgical treatment with a cruciate excision and gentle extraction of the larva was required in this patient, because the larva (approximately 2 cm long) (Panel B) emerged from the lesion spontaneously. The female botfly deposits her eggs on the legs or body of an insect or tick. The patient presumably was infected when bitten by such an insect or tick. At the time of the bite, the botfly eggs hatch, and the larvae quickly burrow into the host's skin. Within days, the host's immune response causes the development of an inflamed furuncle. The larva has characteristic black, backward-pointing spines that anchor it in the host's skin and make removal difficult.
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