A 58-year-old woman working outdoors on a Greek island experienced weeks of worsening facial pain and a severe cough before something alarming happened: she sneezed out wriggling "worms." The creatures turned out to be larvae of the sheep bot fly, a parasite that normally infests the nasal passages of sheep and goats.
An ear, nose and throat specialist surgically removed 10 larvae and one pupa from her maxillary sinuses, the large cavities flanking the nose. Two of the extracted larvae measured between 0.6 and 0.8 inches long, while a wrinkled black puparium — the protective casing in which a pupa matures into an adult fly — still contained remnants of the developing insect, according to a report described by Live Science.
DNA analysis and visual examination confirmed the culprits as Oestrus ovis, the sheep bot fly. The woman worked next to a field where sheep grazed, the likely source of her infection. She was treated with surgical removal and nasal decongestants, and made a complete recovery.
What makes the case so unusual is both the location and the stage of infection. Human cases of O. ovis myiasis have been documented before, but they overwhelmingly affect the eyes, where larvae are deposited in the space between the eyelid and eyeball. Nasal infections are far rarer, and scientists had long believed the parasites couldn't develop very far inside a human host. The discovery of a pupa — a more advanced life stage — challenges that assumption.
The case report authors described the infection as "biologically implausible," underscoring just how unexpected it was to find the parasite thriving and progressing through its life cycle in a person's sinuses. For the patient, the ordeal ended well. For parasitologists, it's a reminder that nature still has surprises in store.
