September 2025, a Greek island. A 58-year-old woman works outdoors, near a field with grazing sheep, notices a swarm of flies around her face, but doesn’t pay too much attention to it. A week later he begins to feel pain in the paranasal sinuses, in the following weeks an intense cough occurs. On October 15, he sneezed and noticed that something resembling a worm had come out of his nose.
The case was documented and published in the journal Emerging Infectious Diseases of the CDC – Centers for Disease Control and Prevention of the United States – in the March 2026 issue. It was signed by researchers Ilias P. Kioulos of the Agricultural University of Athens, Emmanouil Kokkas of the University of Crete and Evangelia-Theophano Piperaki of the School of Medicine of the National and Kapodistrian University of Athens.
What the surgeon found
The patient was referred to an ENT specialist, who performed surgery on the maxillary sinuses — the paranasal cavities on the sides of the nose. The outcome of the operation left the doctors speechless, given the discovery of ten larvae in various stages of development and one pupa, the intermediate stage between larva and adult insect. DNA testing, supported by morphological analysis, identified the organisms as Oestrus ovisthe sheep bot fly, a parasite very widespread in the hot and arid regions of the Mediterranean, whose life cycle normally takes place in the nasal sinuses of sheep and goats.
Biologically implausible
Here lies the point that has attracted the attention of the scientific community. Accidental infestations in humans by Oestrus ovis they are already rare in themselves, but the fact that the larvae could pupate inside the human body had never been observed. The researchers explicitly call it “biologically implausible”: the environment of the human paranasal sinuses lacks the temperature and humidity conditions necessary for pupation, and the secretions, immune responses and local microbial flora normally make that context hostile to the parasite’s prolonged survival.
The researchers point to two factors that likely made the exception possible:
A possible evolution?
The question that the researchers leave open is more disturbing than the clinical case itself, because the case could represent a first sign of evolutionary adaptation of the bot fly, with Oestrus ovis which begins to be able to complete its life cycle in the human host. A possibility that is still speculative, but which, according to the authors, justifies greater clinical attention, given that the species is widespread throughout the world.
After the surgery, the patient was treated with nasal decongestants and achieved complete recovery. None of my work colleagues reported similar symptoms.
