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

• Myiasis of the Intestines

What is Intestinal 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
• Intestinal Myiasis is described as an accidental myiasis where ingestion of contaminated food or water containing fly eggs/larvae cause Myiasis of the Intestines. The causative agents include the lesser housefly (Fannia canicularis) and flesh fly (Sarcophaga sp.). Bedridden or mentally disabled individuals who keep their mouths open while sleeping are also at risk for infestation; the flies lay their eggs around the mouth, which get inadvertently swallowed by the host
• Intestinal Myiasis is not generally known to cause severe tissue destruction and serious complications within the gastrointestinal tract. However, an early management of the condition using suitable medications can result in a good prognosis

Who gets Intestinal Myiasis? (Age and Sex Distribution)

• Intestinal Myiasis is a rare condition that 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. However, most of the cases are reported in developing countries from Asia, Africa, and South America

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

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

• Poor personal and oral hygiene along-with bad breath that attracts flies
• Old age
• Living in poverty and overcrowded unclean surroundings, low socioeconomic status
• Eating and drinking contaminated food/water
• Individuals who habitually breathe through their mouths while sleeping
• Individuals with congenital mouth defects that cause it to remain partly open
• Bad breath (halitosis) that may develop from various dental conditions
• 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 Intestinal Myiasis? (Etiology)

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

• Australian sheep blow fly (Lucilia cuprina)
• Black blow fly (Phormia regina)
• Black soldier fly (Hermetia illucens)
• Common drone fly (Eristalis tenax)
• Common housefly (Musca domestica)
• False stable fly (Muscina stabulans)
• Flesh fly (Sarcophaga sp.).
• Laboratory fly (Megaselia scalaris)
• Lesser housefly (Fannia canicularis)
• Stable fly or barn fly (Stomoxys calcitrans)

An individual may accidently consume food/water contaminated with eggs or larvae of these parasitic flies resulting in Intestinal Myiasis. Also, the parasitic insects either lay eggs or deposit their larvae in the mouth/oral cavity, which are then swallowed. The condition is common in individuals who are unable to take care of themselves, such as those with poor mental health, or comatose patients.

What are the Signs and Symptoms of Intestinal Myiasis?

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

• Stomach or abdominal pain
• Nausea and vomiting
• Itching around the rectal area
• Rectal bleeding and blood in stool
• Intestinal inflammation
• Some individuals may be asymptomatic

How is Intestinal Myiasis Diagnosed?

The diagnostic techniques used may vary based on the specific type of causative parasite. In some individuals, intake of contaminated food/water may result in food poisoning or an intestinal infection (such as due to roundworms) that may cause confusing signs and symptoms, leading to a misdiagnosis or undiagnosed Intestinal Myiasis.

Intestinal Myiasis may be diagnosed on the basis of the following information:

• Complete physical examination and a thorough medical history evaluation
• Laboratory tests: Blood tests, such as complete blood count and peripheral blood smear
• Stool sample analysis for presence of larvae or larval remnants
• X-ray of the abdomen and pelvic region
• Abdominal ultrasound scan
• Capsule endoscopy - for observing the small intestine along its entire length
• CT or MRI scan of the abdomen and pelvic region
• Upper GI endoscopy
• Colonoscopy

A differential diagnosis to eliminate other conditions/infections may be considered, before arriving at a definitive diagnosis. These may include:

• Roundworm infection
• Food poisoning

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 Intestinal Myiasis?

The complications of Intestinal Myiasis may include:

• Severe emotional stress
• Severe abdominal pain and discomfort
• Secondary infection in the gastrointestinal tract
• 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 Intestinal Myiasis Treated?

The treatment for Intestinal Myiasis may involve the following measures:

• Use of purgatives to expel the larvae via feces
• Surgical extraction of the maggots may be undertaken via colonoscopy
• Oral medications such as albendazole, mebendazole, and levamisole
• Administration of broad-spectrum antibiotics, if needed

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

How can Intestinal Myiasis be Prevented?

Intestinal 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 oral ulcers/wounds and oral medical conditions
• Maintain basic personal and community hygiene and proper sanitation is highly important, particularly in the endemic zones
• 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 Intestinal Myiasis? (Outcomes/Resolutions)

• The prognosis of Intestinal Myiasis may vary from one individual to another depending on its severity. It is reported to be normally good with early adequate treatment
• In some individuals, rupture of an abscess containing the larva may lead to a severe inflammatory response

Additional and Relevant Useful Information for Intestinal Myiasis:

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

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