Rhinomyiasis: clinical and surgical management
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Myiasis is a parasitic infection caused by Oestrus ovis, primarily diagnosed in goats and rams in tropical and Mediterranean countries. Humans, different from sheep, are rarely affected by myiasis. Patients usually have symptoms, including a sensation of a small foreign body being struck in the nose and sore throat, sometimes leading to cough, nasal discharge, sneezing, laryngospasm, dyspnoea, and stridor.12

A 39-year-old Italian woman with a clinical history of rhinoseptoplasty and a major depressive episode spent 2?weeks of vacation in Corsica in summer 2018. During her stay, she performed outdoor activities, with subsequent appearance of unilateral nasal respiratory obstruction, cough and pharyngodynia. On her return, she was visited by her physician who prescribed her antibiotic therapy. Owing to the persistence of symptoms, she was then admitted to the Otorhinolaryngology Unit of Biella Hospital, showing mucous rhinorrhoea, frontal cephalgia with less maxillary involvement, olfactory disorders and progressive asthenia; fever was never reported. Fiber-optic endoscopy of the patient’s nose revealed some dark-edged formations, 1?mm in size, at the level of the left middle nasal meatus and near the eustachian tube. The formations, at a closer inspection, seemed to move slowly; therefore, a parasitic infection was suspected, and sampling, under endoscopic guidance, was performed.

The analysis, performed by the Parasitology Laboratory of IZS (Istituto Zooprofilattico Sperimentale), confirmed the morphological identification of O. ovis . Then, a specimen was sent to the Laboratory of Genetics and Immunobiochemistry of the Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta for genetic identification using the forensically informative nucleotide sequencing method.16 Genomic DNA was extracted from the specimen and a portion of the Cox1 gene was amplified by PCR reaction. Genetic analysis confirmed previous morphological identification. Instrumental investigations based on clinical results were performed in the emergency department. Blood chemistry tests showed mild neutrophilia and C reactive protein levels <3?µg/mL. The chest X-ray showed no pulmonary thickening but a modest bilateral reinforcement of the interstitial texture, compatible with mild bronchitis.

Non-contrast maxillofacial CT scan showed bilaterally phlogistic material at the level of the anterior and posterior ethmoid and at the level of the ostiomeatal complex. On the contrary, no evidence of frontal, maxillary and sphenoid sinus involvement was detected (figure 2).Endoscopic examination and CT scan allowed the exclusion of sinonasal malignancies, atrophic rhinitis and neglected nasal foreign bodies.

The patient additionally underwent an eye examination to exclude the simultaneous presence of larvae at the ocular level. No deposits of larvae were identified on the ocular surface, stimulated with a high-intensity light and analyzed up to the level of fornices; the conjunctiva appeared pink, the cornea transparent and mirroring, the aqueous humor optically empty, and the optic disc pink with neat edges, regular vases, and macula. The retina was stimulated in each section through the ophthalmoscope light, with no evidence of subretinal movements due to the presence of larvae.

The patient was submitted to antibiotic therapy, prescribed on the grounds of infectious disease diagnosis to treat bronchitis (ciprofloxacin 500?mg every 12?hours+amoxicillin/clavulanate 1?g every 8?hours for 10 days); no specific antiparasitic therapy was administered considering the side effects (nausea, vomiting, diarrhea, abdominal pain, headache). Once CT scan and infectious and ophthalmological evaluations were performed, the patient urgently underwent endoscopic sinus surgery under general anesthesia.

During the surgery, several larvae were identified inside the nasal cavities (nasal septum, lower and middle nasal meatus) and then removed, whereas no larvae were found at the level of the nasopharyngeal cavity and tubes. The maxillary sinus mucosa was moderately hypertrophic, hyperaemic, and easily bleeding. A lower uncinectomy and bilateral meatotomy were performed; the maxillary cavities, explored with an angled fiber-optic endoscope, appeared empty. Finally, the maxillary and ethmoidal sinuses were washed with 0.9% saline solution. No postoperative complications were observed.