Conjunctival ophthalmomyiasis caused by the sheep nasal botfly (Oestrus ovis).

Three patients had conjunctival ophthalmomyiasis caused by the ovine nasal botfly. All patients had a sudden onset of redness, tearing, and foreign-body sensation of the affected eye. One to nine Oestrus ovis first-instar larvae were removed from the bulbar or palpebral conjunctiva of each patient. Symptoms and clinical signs resolved after mechanical removal of the larvae. Specific taxonomic diagnosis of O. ovis larvae was determined on the basis of characteristic conformation of the terminal end of the larval caudal segment as seen by use of light microscopy.