Achoo fly? One Greek woman’s close encounter with a family of sheep bot flies is nothing to sneeze at.
It all started next to a field of grazing sheep in Greece, where an unidentified 58-year-old was working outdoors in the dry September heat.
She “noticed numerous flies swarming around her face,” according to a new medical report, and about a week later, she began experiencing pain in her sinuses.
The next few weeks brought “severe coughing,” but no other symptoms.
Until one day, Oct. 15 to be exact, she sneezed out a “worm.”
Soon after, an ear, nose and throat doctor got to work surgically removing 10 larvae and a pupa — a teenage insect between the larval and adult stages — from the big sinuses on the side of her nose.
With the help of some nasal decongestants, the woman made a full recovery, and none of her co-workers came forward with similar symptoms.
DNA testing of the dislodged critters, one of which was almost an inch long, revealed they were baby sheep bot flies (Oestrus ovis), a parasite with a well-documented history of taking up residence in the nasal passages of sheep and goats.
Less so in humans.
So how did this horror show wriggle into being?
There have been a handful of cases of these flies setting up shop in human cavities, most commonly around the eyes — a condition known as ophthalmic myiasis — rather than in the nose or mouth. Historically, the larvae in those cases were unable to develop past the first larval stage into full wormlike creatures.
In recent years, that’s changed a bit. There have been reports of later-stage larvae growing in people, especially when the person exhibits immunosuppression or has “traumatic or anatomic abnormalities of the nasal passages.”
The 58-year-old wormectomy patient — whose official diagnosis was “O. ovis nasal myiasis with pupation” — apparently had a seriously deviated septum, keeping the interlopers from being sucked into the nasal passages and allowing them to camp out in the sinuses.
There, they could proceed with their development and even reach the pupation stage — something scientists thought was hitherto “biologically implausible” in any mammal, including in their usual ruminant hosts. (Usually, the larvae grow and molt inside the nasal passages of sheep and goats and are later expelled into the soil, where they pupate.)
Later-stage larvae that get trapped in an animal’s sinuses haven’t been known to pupate, the report explained. “Instead, they desiccate, liquefy or calcify,” sometimes leading to “bacterial superinfection.”
Buzzkill.
In general, healthy, well-functioning sinuses aren’t an ideal landing pad for these baby flies, as certain biological elements create “hostile” conditions for pupation: They’re not the right temperature, humidity levels are wrong, and there are all kinds of mucuses and immune response bacteria that get in the way of pupal development.
Doctors in this case believe the patient’s septum deviation made the difference, somehow changing the environment of the sinuses enough to give the larvae a cozy shelter.
The researchers also posed a disturbing alternative: Maybe this woman’s nightmare head cold was an early sign that the sheep bot fly was adapting into a human bot fly, “enabling O. ovis parasites to complete their life cycle in humans.”
But before the science fiction junkies and doomsday-ers get too ahead of themselves, it would behoove us all to see some more research on the fly’s actual capabilities.
