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

• Pseudomyiasis

What is Accidental 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
• Accidental Myiasis describes an ecological classification of myiasis, wherein fly larvae are inadvertently deposited on living tissue, or accidentally ingested via food and water or inhaled through the nose, to result in the parasitic infection. The condition is also known as Pseudomyiasis
• Based on the anatomical location of the myiasis, Accidental Myiasis includes:
  • Intestinal myiasis
  • Urogenital myiasis (internal)
  • Tracheopulmonary myiasis
• A vast majority of cases of Accidental Myiasis are intestinal myiasis that develops due to intake of contaminated food and water. Some cases of internal urogenital myiasis and tracheopulmonary myiasis are known to be accidental occurrences. The larvae are usually unable to complete their lifecycle within the human hosts
• The signs and symptoms may not be significant in some cases, especially in intestinal myiasis that occurs from ingesting contaminated food and water. Generally, the signs and symptoms and complications depend on the body part involved. An early management of Accidental Myiasis by extracting all larvae and administering antiparasitic medications can result in a good prognosis

Who gets Accidental Myiasis? (Age and Sex Distribution)

• Accidental Myiasis may be observed in individuals of any age group
• Both males and females are affected, and no gender preference is noted
• Worldwide, individuals of all racial and ethnic groups may be affected

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

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

• Poor personal and oral hygiene along-with bad breath that attracts flies
• Old age
• Living in poverty and overcrowded unclean surroundings, low socioeconomic status
• Frequent contact with sheep, goats, horses, and other animals
• Eating and drinking contaminated food/water
• Individuals who habitually breathe through their mouths while sleeping
• Poor toilet facilities
• Urinary tract infection
• Alcoholism and drug addiction
• Differently-abled people, especially those with mental disabilities
• Psychiatric illnesses: Elderly adults, especially those with certain neurodegenerative conditions
• 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 Accidental Myiasis? (Etiology)

Accidental Myiasis offending fly species depend on the location of the condition in the body. It may be caused by any of the following insect larvae species:

• Intestinal myiasis:
  • Common housefly (Musca domestica)
  • False stable fly (Muscina stabulans)
  • Flesh fly (Sarcophaga sp.).
  • Lesser housefly (Fannia canicularis)
• Urogenital myiasis (internal):
  • Psychoda albipennis
  • Latrine fly (Fannia sp.) 
• Tracheopulmonary myiasis:
  • Horse bot flies (Gasterophilus sp.)
  • Rodent bots (Cuterebra sp.)
  • Sheep bot fly (Oestrus ovis)

An individual may accidently consume food/water contaminated with eggs or larvae of these parasitic flies resulting in accidental intestinal myiasis. In some cases, accidental tracheopulmonary myiasis may develop from inhalation of the eggs/larvae.

What are the Signs and Symptoms of Accidental Myiasis?

The signs and symptoms of Accidental Myiasis may vary from one individual to another and may depend on the type of causative larva species, the body systems and organs involved, and the severity of the condition.

Accidental Myiasis affecting the gastrointestinal tract or intestines may result in:

• Stomach or abdominal pain
• Nausea and vomiting
• Itching around the rectal area
• Rectal bleeding and blood in stool

Accidental Myiasis affecting the genitourinary tract may result in:

• Lower abdominal or back pain
• Painful or difficult urination; frequent urination
• Urine may be dark or brown in color
• Obstruction of the urinary tract
• Urinary incontinence

Accidental Myiasis affecting the respiratory tract may result in:

• Whooping cough
• Blood in sputum
• Nasal discharge that is foul-smelling
• Chest pain
• Difficulty in breathing

How is Accidental Myiasis Diagnosed?

The diagnostic techniques used for Accidental Myiasis vary based on the site of myiasis, such as the intestine or genitourinary system, and specific type of causative parasite. The following tests and exams may be required:

• Complete physical examination and a thorough medical history evaluation
• Laboratory tests: Blood tests, such as complete blood count and peripheral blood smear
• Oral and ENT examination
• Urine or stool sample analysis
• X-ray of the affected region
• Abdominal ultrasound scan
• Imaging studies such as CT or MRI scan of the involved region
• Examination of eggs and larvae by a trained entomlogist

A differential diagnosis to eliminate other conditions/infections 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 Accidental Myiasis?

The complications of Accidental Myiasis are based on the part of the body involved. It may include:

• Severe emotional stress
• Severe abdominal pain and discomfort
• Secondary infection in the gastrointestinal, genitourinary, or respiratory tract
• Spread of infection to other areas of the body
• 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 Accidental Myiasis Treated?

The treatment for Accidental Myiasis may involve the following measures:

• Manual removal (where possible) or surgical extraction of the maggots
• Surgical debridement of dead or necrotic tissue after removal of larvae
• Administration of broad-spectrum antibiotics, if needed

How can Accidental Myiasis be Prevented?

Accidental Myiasis may be prevented by considering the following measures:

• Maintain good personal hygiene
• Ensure proper healthcare for those with debilitating conditions, mentally ill, or chronically bedridden
• Keep mouth closed while sleeping
• Stop drug abuse and limit alcohol intake
• Undertake prompt treatment of any ulcers/wounds and other medical conditions
• Maintain basic community hygiene and proper sanitation is highly important, particularly in the endemic zones
• Taking steps to rear healthy farm animals, such as by vaccinating the herd and cleaning sheds regularly
• Quarantining infected herds and eliminating them from the healthy stock of animals
• 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 Accidental Myiasis? (Outcomes/Resolutions)

• The prognosis of Accidental Myiasis may vary from one individual to another depending on its severity. It is reported to be normally good with early adequate treatment (removal of all larvae)

In some individuals, rupture of an abscess containing the larva may lead to a severe inflammatory response

Additional and Relevant Useful Information for Accidental Myiasis:

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

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