Human Oro-Nasopharyngeal Myiasis by Chrysomya Bezziana (Old-World Screwworm): The First Reported Case in Sri Lanka.

Myiasis is the invasion of mammalian tissues by dipterous larvae. Cutaneous myiasis is the commonest type, and less commonly, internal tissues and organs are affected. Here, we report the first case of oro-nasopharyngeal myiasis caused by the third-instar larvae of Chrysomya bezziana (Old-World screwworm) in Sri Lanka. A retired 71-year-old female tea-plucker presented to the hospital with a 4-day history of nasal bleeding and neck discomfort. Except for well-controlled hypertension, she had no significant medical history. On examination, there was an ulcerated area in the posterior oro-nasopharynx filled with maggots. Hematological analysis showed a high C-reactive protein level (24 mg/dL) and white blood cell count (17.5 × 109/L) with 80% neutrophils. Computed tomography showed severe inflammation of the pharynx with no features of a neoplasm or parapharyngeal abscess. An examination was performed under anesthesia followed by manual removal of larvae, surgical debridement with biopsy, and treatment with antiparasitic medicines and antibiotics. Histopathology excluded neoplasm and only showed inflammatory changes. All extracted larvae were morphologically similar and identified as third-instar larvae of C. bezziana using a trinocular zoom stereomicroscope. The patient recovered and was discharged from the hospital on the 15th day and was well at 2 months follow-up.