Bot fly larvae (Cephenemyia jellisoni) as a cause of neurologic signs in an elk.

In June 1993, a yearling female elk (Cervus elaphus) near John Day, Oregon (USA) was observed twice over a four week period with signs of neurologic disease including weakness, walking in circles with an uncoordinated gait and disorientation. The elk was shot, and the head and neck were examined grossly for parasites and lesions. Thirty-five second and third instar larvae of Cephenemyia jellisoni were recovered from an encapsulated space in the nasopharyngeal area dorsal to the soft palate. Larvae protruded into the caudodorsal end of the ventral nasal meatus, obliterating the opening of the left eustachian tube. Larvae were not recovered from their normal location in the retropharyngeal recesses. Thus the effects of several Cephenemyia jellisoni larvae in an aberrant location mimicked signs observed in meningeal worm infections.