A 58-year-old Greek woman suffered from pain in the middle of her face that gradually increased while she was working outdoors on one of the Greek islands.
Two to three weeks later, she developed a severe cough, and then noticed "worms" coming out of her nose when she sneezed, which prompted her to seek medical attention.
Upon examination, an ear, nose, and throat specialist removed 10 larvae and one pupa (the insect's life cycle stage between larva and adult) from the maxillary sinuses, the large cavities on either side of the nose. Detailed examination revealed that one larva was yellow and 15 millimeters long, another was light brown and 20 millimeters long, while the pupa's casing was black, wrinkled, and contained remnants.
Analysis revealed that these organisms were larvae of the sheep fly (Oestrus ovis), a parasite that commonly infects sheep and goats in their nasal passages and sinuses. The area where the patient worked was near a field where sheep grazed, which explains the likelihood of her exposure to the infection.
The patient was diagnosed with "sheep fly nasal myiasis with pupal stage," a rare diagnosis for humans, as these parasites usually infect the eyes, laying their larvae in the conjunctival sac between the eyelid and the eyeball, while their presence in the nose is an exceptional case.
The patient received surgical treatment to remove the larvae and pupa, as well as nasal decongestant medication, and subsequently made a full recovery.
Larvae typically go through several developmental stages, with L3 being the final stage, where the larva becomes large and almost fully formed. Afterward, it enters a stage called pupation, during which the larva transforms inside a cocoon-like shell before becoming an adult insect.
This case demonstrates that the sheep fly can partially complete its life cycle inside humans, even though the sinuses do not usually provide a suitable environment. This may be due to specific anatomical factors, such as the patient's deviated septum and the large number of larvae, which hindered their exit and allowed them to progress to the L3 stage and pupal stage, a very rare transitional stage in humans.
The researchers pointed out that doctors in affected areas should be aware of this rare possibility, closely monitoring for any similar symptoms, so that such cases can be detected early and treated successfully.
