An Unexpected Cause of Eye Irritation: A Case of Zoonotic Ocular Onchocerciasis

A 19-year-old male residing in Pittsburgh presented with irritation and watering from his right eye and was diagnosed to have a right subconjunctival nodule. Surgical excision revealed both dead and living worms and histopathological staining of the worms confirmed these to be zoonotic species of Onchocerca. The morphologic characteristics of the worm suggest it to be either O. lupi or O. lienalis which were first detected in wolves and cattle, respectively. Mystery remains as to the mode of transmission and the hosts for this parasite in this part of the United States. This case adds to the growing number of cases of zoonotic ocular onchocerciasis reported from all over the world.