Zoonotic filaria in a subcutaneous artery of a child in Costa Rica.

A 2-year-old boy from a rural community of Costa Rica was admitted to hospital with a rash of increasing severity over an area of the flank about 8 cm in diameter. Sections of a biopsy from the center of the affected area revealed a necrotic mature, infertile, female filaria about 120 microns in diameter in a subcutaneous artery, surrounded by a layer of dense eosinophilic granulomatous reaction which at one point, along with the worm, extended into the dermis. The worm, readily distinguished from Dirofilaria, Onchocerca, Wuchereria and Brugia, was unidentified.