Nasal cavity myiasis presenting with preseptal cellulitis

AbstractNasal Myiasis is the infestation of the nasal cavity by dipterous larvae and which are commonly documented in developing countries where sanitation is a public problem. Other predisposing factors being poorly nourished patient with poor hygiene, atrophic rhinitis, and diabetic with purulent nasal discharge, midline granulomatous lesions or malignancy involving the nose. We have reported a case of a patient with underlying sinonasal tumour post excision and postoperative concurrent chemoradiation presenting with preseptal cellulitis and nasal myiasis.


Introduction
Infestation of human and vertebrate animal by larvae of insects is known as Myiasis; these larvae feed on the living and dead tissue from the host or on fluid substance. The presence of the larvae within the nasal cavity is known as Nasal Myiasis, this condition although rare can be a very embarrassing situation to the patient. It is a common occurrence in developing countries where sanitation is a public problem [1]. Other predisposing factors being poorly nourished patient with poor hygiene, atrophic rhinitis, and diabetic with purulent nasal discharge, midline granulomatous lesions or malignancy involving the nose. We are reporting Management of Nasal Myiasis in a patient who previously diagnosed with a recurrence of sinonasal malignancy.

Case report
A 68-year-old Chinese gentlemen with underlying recurrent sinonasal cancer underwent surgical resection, and postoperative concurrent chemoradiation therapy in April 2016, currently presented with left facial and periorbital pain, swelling, and redness with associated nasal discharge and blurring of vision for past two weeks. On examination of the patients face, there was left periorbital region oedema and redness. Nasal endoscopy of the left nasal cavity reveals multiple fly larvae which were seen crawling within the crevices of the nasal cavity ( Figure 1). MRI orbit and paranasal sinuses showed what appeared to be the presence of larvae surrounding the area of the left orbital region (Figure 2). Removal of the fly larvae was aided by nasal flushing with turpentine three times daily, while an inflated Foley catheter balloon is used to occlude the posterior nasal space while the turpentine was applied. Fly larvae were seen crawling out of the crevices nasal cavity as a result of turpentine fumes suffocation. The patient was discharged well after 4 d of the procedure and was given nasal douching and to be reviewed again in 1 week. During follow-up, patient preseptal cellulitis has completely resolved, and examination of the nasal cavity did not reveal any presence of fly maggots or necrotic tissue.

Discussion
Myiasis is the infestation of live vertebrates (humans and animals) with dipterous larvae. The name of the condition derived from the ancient Greek word Myia meaning fly. Myiasis varies widely on the form it takes and the effect it has on its victim, and it depends on the type of fly larvae and the location of the larvae in the human body. Flies may lay their eggs in open wound; other larvae may invade unbroken skin or even enter the body through the nose or ears [2]. Myiasis is classified based on the ICD-10 into dermal, sub-dermal, cutaneous, nasopharyngeal (nose, sinus, and pharynx), ocular, Auricular, intestinal, or urogenital [3].
Flies will deposit their eggs within the host, and from these emerge larvae between 8 and 24 h depending on the species and temperature. These larvae will feed on the infected or dead tissue and secretion over a period of few days until grown. Larvae will later leave the host and carry on developing in an isolated place. The larva remains. Still, its exoskeleton gets dark, and then it begins its pupal stage. From this moment it undergoes an important physical change, emerging as an adult fly from 1 to 3 weeks later.
Worldwide, the most common flies that cause the human infestation are Dermatobia hominis (human botfly) and Cordylobia anthropophaga (tumbu fly). The order Diptera is a large order of insects that are commonly known as true flies. Flies are ubiquitous and abundant, with approximately 150,000 species in 10,000 genera and 150 families. This order contains most of the insects vectoring diseases in humans.
The order Diptera is divided into two suborders, the Nematocera and the Brachycera. The Nematocera contain most families of blood-feeding flies that serve as vectors for a variety of viral, protozoan, and helminthic diseases, especially the Culicidae. Rarely, agents in this suborder can cause accidental myiasis. The Brachycera are composed of infraorders. The infraorder Muscomorpha or "Cyclorrhapha" contains all species that cause specific myiasis and most of the species responsible for facultative myiasis, especially the species within the Calyptratae. The Taxonomic division of calyptratae can be further divided into families of Muscidae, Fanniidae, Oestridae, Calliphoridae, and Sacrophagidae.
Ophthalmomyiasis, or oculomyiasis, is the infestation of any anatomic structure of the eye. Further subclassified of this group are ophthalmomyiasis externa (or superficial) and ophthalmomyiasis interna. Ophthalmomyiasis externa refers to the superficial infestation of ocular tissue. Conjunctiva myiasis is the most common form of ophthalmomyiasis, and it is a relatively mild, self-limited, and benign disease. Patients commonly present with acute foreign-body sensation. Upon examination, there will be presence of the larva movement across the external surface of the eyeball, any of the following symptoms may be found upon an ophthalmologic examination: red eye, photophobia, conjunctival hyperaemia, lid oedema, punctate conjunctival haemorrhages, pseudomembrane formation, and superficial punctate keratopathy [4].
Patient with nasal myiasis commonly presents with epistaxis, foul smell, and the passage of worms, facial  pain, nasal obstruction, nasal discharge, headache, dysphagia, and sensation of foreign body in the nose [5,6]. Endoscopic examination of the nasal cavity will reveal an oedematous, ulcerated mucous membrane filled with necrotic material, and crawling maggots. Patients may have a septal perforation or palatal perforation or both. Erosion of the bridge of the nose and adjacent area of the face, as well as orbital cellulitis and diffuse cellulitis of the face, may occur. In a smaller number of patients, examination reveals extensive ulceration of the tonsils and the posterior pharyngeal wall due to maggots [7].
Magnetic resonant imaging (MRI) is imaging option in cases of nasal myiasis to rule out infiltration of the larvae into the orbit, facial, or brain. In our case, MRI scan was reported by the radiologist as sinonasal tumour recurrence.
Treatment of nasal myiasis aimed towards removal of the invading parasite. Removal with the aid of an endoscope can be a difficult task as the larvae burrow within the crevices of the nasal cavity mucosa. In the case discussed above, the patient had undergone medial maxillectomy for initial sinonasal tumor, given this situation the larvae were seen occupying the mucosa surrounding the orbit as well as the ethmoidal and sphenoidal sinuses.
Removal of the larvae can be aided by the use of several substances including placing petroleum jelly, liquid paraffin, beeswax, turpentine, and chloroform. This approach takes advantage of the larva's oxygen requirement, encouraging it to exit on its own. Evidence has shown that, larvae will begin to emerge within 3-24 h after application of these materials [8]. An alternative treatment for all types of myiasis is oral ivermectin or topical ivermectin (1% solution), proven especially helpful with oral and orbital myiasis [9].
Care must be taken to extract the larva whole. Otherwise, a considerable foreign body reaction may ensue. Also, in the case of secondary pyogenic infection, appropriate antibiotics should be administered. Vaccination should be considered in affected individuals as myiasis can be a portal of entry for Clostridium tetani.

Conclusions
Nasal myiasis should be considered as a differential diagnosis with patient presenting with orbital or preseptal cellulitis. Larvae may extend rapidly into surrounding nasal cavity tissue resulting in debilitating consequences. Therefore, prompt treatment should be taken with turpentine application and endoscopic removal of larvae and follow up.

Disclosure statement
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.