What are the other Names for this Condition? (Also known as/Synonyms)

• Myiasis of the Nasal Cavity
• Nasal Cavity Myiasis

What is Nasal Myiasis? (Definition/Background Information)

• Myiasis is primarily a skin disease caused by several species of parasitic fly larva (of taxonomic order Diptera). The fly larvae (maggots) cause disease in humans and other vertebrate animals by feeding on the tissues. The infection is usually characterized by a painful, itchy, boil-like skin lesion that contains the parasite within it
• Nasal Myiasis is a form of myiasis that develops in the nose, due to infestation of the nasal cavity by fly larvae or eggs, usually when the individual sleeps. The main causative agents for the condition are the screw-worms and bot flies. The condition develops aided by factors such as poor personal hygiene, advancing age, mental illnesses, and atrophic rhinitis
• Nasal Myiasis can cause severe and extensive tissue destruction and serious complications, if not immediately addressed. Management of the condition involves removal of all larvae followed by surgical debridement of necrotic tissue. Nevertheless, the prognosis of Nasal Myiasis depends on its severity; mild cases have better prognosis than severe cases

Who gets Nasal Myiasis? (Age and Sex Distribution)

• Nasal Myiasis may be observed in individuals of any age group, although most cases are noted in adults over the age of 50 and children
• Both males and females are affected, and no gender preference is noted
• Worldwide, individuals of all racial and ethnic groups may be affected. However, most of the cases are reported from the developing nations of Asia, Africa, and South America

What are the Risk Factors for Nasal Myiasis? (Predisposing Factors)

There are a variety of risk factor for Nasal Myiasis (mainly in the endemic regions). Often, a combination of risk factors may be observed. The predisposing factors include:

• Atrophic rhinitis is a very common risk factor for individuals presenting Nasal Myiasis
• Poor personal hygiene
• Individuals who are unable to keep their nose chronically clean due to ill-health or hand deformities
• Living in poverty and overcrowded unclean surroundings, low socioeconomic status
• Poor nutritional status
• Old age
• In rare cases, chronic nose bleeding, or excess drainage from the nose. Foul-smelling nasal discharge can attract flies
• Leprosy
• Tuberculosis
• Rhinoscleroma, a bacterial infection of the nose
• Alcoholism and drug addiction
• Differently-abled people, especially those with mental disabilities
• Psychiatric illnesses: Elderly adults, especially those with certain neurodegenerative conditions
• Uncontrolled diabetes
• Immunocompromised status
• Bedridden patients who cannot care for themselves

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Nasal Myiasis? (Etiology)

Nasal Myiasis is a parasitic infection of the nasopharynx caused by any of the following species of insect larvae:

• Blue bottle fly (Calliphora vicina)
• Common green bottle fly (Lucilia sericata)
• New World screw-worm fly (Cochliomyia hominivorax)
• Old World screw-worm fly (Chrysomya bezziana)
• Sheep bot fly (Oestrus ovis)
• Spotted flesh fly or screwworm fly (Wohlfahrtia magnifica)
• Vinegar fly (Drosophila melanogaster)

The parasitic insects either lay eggs or deposit their larvae in the nose, typically when an individual is asleep; up to 200 eggs may be laid by an adult fly. In some cases, the condition may develop from ingestion of the eggs/larvae.

The condition may develop secondary to atrophic rhinitis and/or aided by factors such as poor hygiene and lack of mental alertness. Individuals with long-term smelly nasal discharge may also attract flies to their nose.

What are the Signs and Symptoms of Nasal Myiasis?

The signs and symptoms of Nasal Myiasis may vary from one individual to another and may also depend on the type of causative larva species. In many individuals, the following may be noted:

• Localized pain in the nose
• Generalized facial pain
• Severe irritation in the nose
• Foreign body sensation in the nose
• Congestion
• Sneezing
• Presence of a lesion/ulcer
• Nosebleed
• Foul-smelling nasal discharge consisting of blood, mucus, and pus
• Loss of smell
• Individuals can sense movement of the larva in their nose/nasal cavities
• Swelling of the face, lips, eyelids, and other affected areas
• In debilitated patients, caregivers may be able to visually observe larva in the nasal cavities

If the larvae move to other parts of the face, such as to the mouth or throat, additional signs and symptoms may be noted.

How is Nasal Myiasis Diagnosed?

Nasal Myiasis is diagnosed on the basis of the following information. The diagnostic techniques used may vary based on the specific type of causative parasite.

• Complete physical examination and a thorough medical history evaluation
• ENT examination
• CT scan of the sinuses 
• Nasal endoscopy or rhinoscopy
• Imaging studies of the head and neck region
• Laboratory tests: Blood tests, such as complete blood count and peripheral blood smear

A differential diagnosis to eliminate other conditions/infections, such as sinusitis, may be considered, before arriving at a definitive diagnosis.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Nasal Myiasis?

The complications of Nasal Myiasis can be significant and may include:

• Severe emotional stress
• Severe pain and discomfort
• Formation of fistula
• Secondary infection of the sinus l cavities and nasopharynx
• Infections involving the eye (orbit)
• Perforated septum and/or palate
• Facial cellulitis: Skin infection that involves the deeper skin tissues
• If the central nervous system/brain is affected, it can result in meningitis and pneumocephalus
• Hypereosinophilia and leukocytosis (increased white blood cells)
• Severe inflammatory response to dead larvae or parts of larvae, especially during its removal
• Sepsis, which can be life-threatening

How is Nasal Myiasis Treated?

The treatment goals for Nasal Myiasis includes limiting tissue necrosis/destruction and prompt visualization and removal of the parasitic larvae. The treatment may involve:

• Use of turpentine/oil/chloroform to immobilize and/or kill the maggots
• While performing a nasal endoscopy, special forceps may be used to remove the larvae
• Manual extraction of larvae when endoscopic removal through forceps is unavailable
• Irrigation of the nasal cavity before and after extraction of all larvae
• Surgical extraction of the maggots may be undertaken if necessary, followed by surgical debridement of necrotic tissue
• Administration of broad-spectrum antibiotics
• Topical or oral medications containing ivermectin
• Undertaking treatment for any underlying condition is also important

Examination and identification of the larva following removal from skin tissues may be undertaken.

How can Nasal Myiasis be Prevented?

Nasal Myiasis may be prevented by considering the following measures:

• Maintaining good personal hygiene
• Maintain basic personal and community hygiene and proper sanitation is highly important, particularly in the endemic zones
• Undertake prompt treatment of any nasal ulcers/wounds and medical conditions related to the nose and nasal cavity
• Controlling diabetes through lifestyle changes
• Stop drug abuse and limit alcohol intake
• Use insect repellents to prevent the insects from entering residences
• The growth of adult flies must be effectively controlled and methods for eradication followed on a regular basis

What is the Prognosis of Nasal Myiasis? (Outcomes/Resolutions)

The prognosis of Nasal Myiasis may vary from one individual to another depending on its severity. However, in many cases, the prognosis is good with early diagnosis and treatment (removal of all larvae).

• Extensive tissue destruction with involvement of the neurological system and delayed/inadequate treatment may result in severe complications that may even be fatal
• In some individuals, rupture of an abscess containing the larva may lead to a severe inflammatory response

Additional and Relevant Useful Information for Nasal Myiasis:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/skin-disorders/