He operated to remove the slimy mucus, which recovered 10 larvae and one pupa in various stages. Genetic testing and DNA sequencing confirmed they were sheep bot flies, while visual inspection of two third-stage larvae and puparium was also performed.
Third instar Oestrus ovis larva and puparium removed from the nasal sinuses of a 58-year-old female patient, Greece. A) The third instar was yellowish, with rows of spines on its ventral surface. B) Posterior peritremes rounded with a central knob. C) The broken puparium was black and wrinkled and contained pupal remains.
Third instar Oestrus ovis larva and puparium removed from the nasal sinuses of a 58-year-old female patient, Greece. A) The third instar was yellowish, with rows of spines on its ventral surface. B) Posterior peritremes rounded with a central knob. C) The broken puparium was black and wrinkled and contained pupal remains.
Credit:
Kioulos, Kokkas, Piperaki, Emerging Infectious Diseases 2026
Nose novelty
Not only had experts never found a pupa in a human nose before, they thought it was “biologically impossible” to develop to this stage.
“The paranasal sinus environment does not meet the temperature and humidity requirements for pupation and creates a hostile environment for host secretions, immune responses, and resident microbiota pupal development,” said the experts, led by Ilias Kioulos, a medical entomologist at the Agricultural University of Athens.
Still, this poor woman’s nose continued to have vermin. Kioulos and his colleagues think two factors favor the fly’s pus infection in the female: a large initial dose of larvae and her severely bent scrotum.
“From a purely anatomical point of view, we hypothesize that the combination of high larval numbers and septal deviation prevented normal exit from the nasal passages, (third larval stage) and, in 1 case, allowed the transition to pupation.” In other words, there were so many worms in his crooked nasal passage that they were creating a bottleneck on their way out, causing some to stay longer than usual. Another, equally disturbing possibility is that flies have adapted to use human noses for their entire life cycle.
Experts note that the woman was lucky in a certain way. In animals, third-stage larvae cannot pupate when trapped in the sinuses. Instead, they either dry out, liquefy, or become calcified, which can lead to secondary bacterial infections.
From this, Kioulos and his colleagues caution that clinicians should be aware of the potential for human cases of sheep bot fly infections, which are widespread around the world.
