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

• Furuncular Myiasis
• Furunculoid Myiasis

What is Furunculous 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
• Furunculous Myiasis or Furuncular Myiasis is a form of cutaneous myiasis that is mostly caused by the larvae of the South American human botfly and the African tumbu fly. A ‘furuncle’ describes an inflamed pus-filled skin lesion/boil due to infection in the hair follicles
• Eggs of the parasitic fly hatch into larvae and penetrate the host skin; an infestation leads to infection that develops, which is visible within 10-15 days in the form of a furuncular lesion that presents severe stabbing pain, itchiness, and discharge. Without suitable medical intervention, the larva grows and matures within 2-3 months and exits (outwards) from the lesion
• It is difficult to address Furunculous Myiasis via conventional non-invasive methods alone. Generally, the preferred treatment is a surgical excision to remove the larva. Following its successful extraction, the wound heals, and the outcomes are mostly good unless complications, such as sepsis, develops

Who gets Furunculous Myiasis? (Age and Sex Distribution)

• Furunculous Myiasis is a rare fly larvae infestation of the body. The exact prevalence is not known
• The presentation of symptoms may occur at any age; both males and females are affected
• Individuals of all racial and ethnic groups may be affected
• Geographically, Furunculous Myiasis is endemic to sub-Saharan Africa and certain regions in central and south America 

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

The following are the risk factors for Furunculous Myiasis: (mainly in the endemic regions)

• Living in or visiting South America or sub-Saharan Africa
• Individuals who work outdoors, especially in forests, such as wildlife conservationists, archaeologists, tourists to the region, farmers and plantation workers, miners, etc.
• Wearing wet clothes
• Using contaminated clothes (washed and dried outside) without ironing
• Contact with animals in the endemic regions

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 Furunculous Myiasis? (Etiology)

Furunculous Myiasis is a parasitic infection caused by the following insect larvae:

• African tumbu fly or mango fly (Cordylobia anthropophaga): These lay eggs on the soil, usually tainted by urine or feces, or on clothing/bedding. Once they hatch, the larva waits for a suitable human host. On contact with humans, the larva penetrate the skin and resides and feeds on the subcutaneous skin layers
• Human botfly (Dermatobia hominis): It is found in Central and South America, including parts of Mexico. The eggs of the tiny botfly are deposited on the abdomen of a mosquito. The eggs get transmitted to its human host when the mosquito feeds on human blood. The larvae are able to penetrate unbroken human skin and then grows and develops by feeding on the skin tissues

Other causative parasites include rodent bots (Cuterebra spp.) and the myiasis fly (Wohlfahrtia vigil) in North America. Rarely, the Lund fly (Cordylobia rhodaini), which is commonly found in sub-Saharan Africa can also cause Furuncular Myiasis.

What are the Signs and Symptoms of Furunculous Myiasis?

The signs and symptoms of Furuncular Myiasis may include the following:

• Swelling and redness on the skin of exposed or non-exposed parts of the body
• Appearance of an enlarging skin lesion that is red and inflamed
• Abscess formation, with a white central plug-like spot (this spot often houses the live larva)
• Most of the lesions appear on the face, scalp, or arms and legs
• Oozing of pus from abscesses or a clear fluid from the white plug
• Once the larva matures into an adult, it bursts open the boil and drops to the ground

How is Furunculous Myiasis Diagnosed?

Furunculous 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, with emphasis on recent travel and/or handling of animals which may be infected
• Assessment of signs and symptoms, including a visual examination of the lesion
• Laboratory tests: Blood tests, such as complete blood count, which may show increased white blood cells
• Imaging studies, as necessary: Ultrasound scan of the affected region to localize the larva and extent of involvement. This can help enable the surgeon to remove the larva without damaging the surrounding tissues

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 Furunculous Myiasis?

The complications of Furunculous Myiasis may include:

• Severe emotional stress
• Severe pain and discomfort
• Secondary infection of the abscess; rupture of the abscess
• Cellulitis: Skin infection that involves the deeper skin tissues
• Severe inflammatory response to dead larvae or parts of larvae, especially during its removal
• Sepsis, which can be life-threatening

How is Furunculous Myiasis Treated?

The treatment for Furunculous Myiasis may involve the following measures. However, generally the most effective way to treat myiasis is via surgery.

• Asphyxiating the larvae by plugging the central pore of a lesion with petroleum jelly, paraffin, or sticky plasters (the central pore has an opening that allows airflow for larval breathing)
• Infusion of lesion with lidocaine/epinephrin to visualize the larval head, followed by removal of larva
• Insecticides to kill the larva within the abscess
• Surgical extraction of the larva from affected skin. Care must be taken to excise the complete larva from the abscess; breaking or rupturing the larva while extracting it, can result in severe inflammatory reactions
• Dressing and wound care, as required

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

How can Furunculous Myiasis be Prevented?

Furunculous Myiasis may be prevented by considering the following measures:

• Maintaining basic personal and community hygiene and proper sanitation is highly important, particularly in the endemic zones
• Extra care should be taken while travelling to tropical and sub-tropical areas
• Try to cover all portions of the skin using long-sleeved shirts, full trousers, and socks to protect the body and skin from insect bites
• Use insect repellents to prevent the insects from entering residences
• Dry clothes in direct sunlight
• Iron clothes to help kill the eggs, which may have been laid on damp clothes
• Seek medical attention for any changes in skin; especially, after visiting known endemic regions
• The growth of adult flies must be effectively controlled and methods for eradication followed on a regular basis

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

The prognosis of Furunculous Myiasis is good, if the larva or larvae can be located and removed completely from the body.

• In some individuals, rupture of an abscess containing the larva may lead to a severe inflammatory response 
• Additionally, life-threatening sepsis may occur due to secondary infections

Additional and Relevant Useful Information for Furunculous Myiasis:

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

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