Diagnostic dilemma: Woman’s “biologically impossible” infection causes “worms” to come out of her nose when she sneezes

Patient: 58-year-old female resident in Greece

Symptoms: A patient working outdoors on a Greek island experienced pain near the center of his face that gradually worsened. About 2-3 weeks after this pain started, she also developed a severe cough.

Shortly after, she told doctors, she went to see a doctor because “bugs” came out of her nose when she sneezed.

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What happened next: The case report form does not say how the patient was tested. However, it states that an ear, nose and throat specialist surgically removed the wriggling creature from her maxillary sinus (a large sinus cavity on the side of the nose). These creatures included 10 larvae and one pupa (the insect life stage between the larval and adult stages).

After the extraction, experts took a closer look at the two larvae and part of the pupal chamber (the protective outer shell of the pupa until it becomes an adult). One larva was pale yellow and about 15 mm long, and the other was light brown and 20 mm long. The pupal chamber was black and wrinkled and contained pupal remains, the researchers noted.

The research team visually inspected the larvae and extracted their DNA for analysis.

Diagnosis: Testing revealed that this worm-like creature was a larva of the sheep fly (Oestrus ovis). This parasite is usually found in the nasal cavities and sinuses of sheep and goats. Notably, the outdoor areas where women worked were located next to fields where sheep were grazed, the report authors wrote.

Since fly infections caused by parasitic worms are commonly known as “pupariosis,” the woman was diagnosed with “O. ovarynaris with pupation.”

Treatment: In addition to surgically removing the larvae and pupae from the sinuses, the woman was given a nasal decongestant. After these two treatments, she made a “complete recovery,” according to the report.

What’s unique about this case: Although human cases of O. ovis myiasis have been reported in the past, these infections usually affect the eyes rather than the nasal cavity.

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“The O.ovis bot fly rarely affects humans, and in most cases the larvae inhabit the conjunctival sac between the eyelid and the eyeball,” the authors note. In rare cases, flies have also been reported to introduce larvae into human nostrils, mouths, and ear canals.

Historically, it was thought that O. ovis could not develop in the human body for long periods of time and only grew to the first larval stage known as L1. However, older larvae, including L2 and L3, have been identified in recent cases, the report authors wrote. Pupation, the point at which the larva develops into a “teenager,” follows the L3 stage.

“The patient we reported had a severely deviated nasal septum and appeared to have been inoculated with a large number of larvae,” the researchers noted. “From a purely anatomical point of view,” the authors hypothesize that the large number of larvae, combined with the female’s deviated septum, may have prevented the larvae from exiting through the nose. The researchers concluded that this allowed the larvae to progress to the L3 stage and, in some cases, pupate.

When infecting sheep or goats, the adult female O. ovis deposits larvae (also called maggots) in and around the host animal’s nostrils. The larvae then travel to the nasal cavities and sinuses, where they may mature for several months before exiting through the nostrils. Once they emerge, they burrow into the ground and enter a pupal phase that lasts several weeks. Upon maturity, the adult moth is released from the pupal chamber and emerges from the ground.

In some cases, L3 larvae can become lodged in the host animal’s nasal cavity, but they usually do not pupate at that point. Instead, they typically dry, liquefy, or calcify, and the debris can cause secondary bacterial infections.

The maggots die because the sinuses do not provide a favorable environment for them to enter the pupal stage. Therefore, “pupation of O. ovis larvae within a mammalian host is considered biologically improbable,” the authors write. Nevertheless, it happened to their patients.

The authors suggest that some “unidentified anatomical or physiological factor” must have enabled pupation in this female case. Alternatively, the researchers thought, this strange event may reflect an evolutionary adaptation that allows the species to complete its life cycle inside humans.

“In either scenario, additional cases and data are needed to understand this phenomenon, but clinicians need to be aware of the possibility of human fly infection in endemic areas,” the researchers concluded.

For more interesting medical cases, check out our Diagnostic Dilemma archives.