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# Tungiasis and furuncular myiasis

Tungiasis (sand flea, «nigua») and furuncular myiasis (bot-fly larva, «nuche») are [skin](https://durgical.com/en/anatomy/skin/) infestations common in rural Colombia that cause painful nodules.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Skin](https://durgical.com/en/anatomy/skin/)
- [Big toe](https://durgical.com/en/anatomy/great-toe/)
- [Second toe](https://durgical.com/en/anatomy/second-toe/)
- [Little toe](https://durgical.com/en/anatomy/little-toe/)
- [Calcaneus](https://durgical.com/en/anatomy/calcaneus/)

## Microorganisms that cause it

- [Tunga penetrans](https://durgical.com/en/microbiology/tunga-penetrans/)
- [Dermatobia hominis](https://durgical.com/en/microbiology/dermatobia-hominis/)

## What it is

Two parasitic skin infestations that produce painful nodules and are frequent in rural tropical areas. In tungiasis, the female sand flea Tunga penetrans burrows into the skin, usually of the toes, and swells with eggs. In furuncular myiasis, a fly larva, in the Americas mainly the human bot fly Dermatobia hominis, develops inside a boil-like lesion with a central breathing pore.

## Who gets it

Both are neglected tropical skin diseases of poor rural communities. Tungiasis affects people in South America (including Colombia), the Caribbean and sub-Saharan Africa who live with earth floors and walk barefoot; children and older adults carry the heaviest burden, and pigs, dogs and rats are reservoirs. Dermatobia myiasis is endemic from Mexico to northern Argentina, including Colombia's warm rural zones, and also affects travellers.

## Causes

- Tungiasis: impregnated female sand flea (Tunga penetrans), known as chigoe, jigger or «nigua», living in dry sandy soil and earth floors
- Furuncular myiasis: larva of the human bot fly (Dermatobia hominis, «nuche» or «tórsalo»), whose eggs are carried to the skin by mosquitoes or other flies; the larva enters through the bite or intact skin
- Other myiasis: wound myiasis by screwworm flies (Cochliomyia hominivorax) in neglected wounds

## Risk factors

- Walking barefoot and living in houses with earth floors (tungiasis)
- Poverty, crowding and contact with infested animals (pigs, dogs, cattle)
- Rural or forest exposure in the tropics (myiasis)
- Open or neglected wounds, poor hygiene, older age, alcohol use disorder or neurological disability (wound myiasis)

## Pathophysiology

In tungiasis, the female flea penetrates the epidermis, keeps its rear end open to the surface to breathe, mate and expel eggs, and enlarges to a pea-sized nodule over about two weeks before dying in the skin. The dead flea and its bacteria trigger intense inflammation. In furuncular myiasis, the bot-fly larva grows in the dermis for 6–12 weeks, feeding on tissue and breathing through a skin opening, with backward-pointing spines that anchor it and cause pain.

## Classification

- Tungiasis: by stage (penetration, hypertrophy with a white nodule and central black dot, involution) and by severity
- Myiasis: furuncular (Dermatobia), migratory, wound (traumatic) and cavitary (nasal, ocular, aural)

## Symptoms and signs

- Tungiasis: itchy then painful white or yellowish papule or nodule with a central black dot, typically around and under toenails, between toes and on the heel
- Tungiasis: several to many lesions, clusters, nail deformity and difficulty walking
- Myiasis: boil-like painful nodule with a central pore that may leak serous fluid
- Myiasis: sensation of movement or stabbing pain inside the lesion; bubbles when the pore is covered with liquid
- Myiasis: usually on exposed skin such as the scalp, arms and legs

## Red flags

- Spreading redness, abscess, lymphangitis or fever (bacterial superinfection)
- Unvaccinated patient with wounds from flea removal or myiasis (risk of tetanus)
- Myiasis near the eye, nose, ear or a large open wound (tissue destruction)
- Many lesions with inability to walk, particularly in children or older adults

## Diagnosis

**Clinical**
Clinical: in tungiasis, a nodule with a central black dot in typical foot locations in someone from an endemic area; in myiasis, a boil-like lesion with a central pore, movement and history of exposure. Dermoscopy shows the flea's rear end and eggs, or the larva's spiracles.

**Tests**
Identification of the extracted flea or larva confirms the diagnosis and the species. Wound culture when superinfection is suspected. Check tetanus vaccination status.

**Imaging**
Ultrasound can show the larva and its movement in furuncular myiasis or deep lesions.

## Differential diagnosis

- Bacterial furuncle or abscess
- Plantar wart and paronychia
- Cutaneous larva migrans
- Insect bite reaction or epidermoid cyst
- Foreign-body reaction

## Goal of treatment

Remove the parasite completely and safely, prevent and treat bacterial infection and tetanus, and reduce reinfestation by protecting feet, improving floors and treating animal reservoirs.

## Treatment

**Procedure**
Tungiasis: sterile extraction of the entire flea with a needle or curette, widening the opening and avoiding rupture; Myiasis: occlusion of the pore (for example with petrolatum) to force the larva up for extraction, or a small incision with removal under local anaesthesia.

**Medical**
Topical dimeticone (low-viscosity silicone oils) kills embedded fleas and is useful when lesions are numerous; topical or oral antibiotics for secondary infection; ivermectin is sometimes used in myiasis.

**Acute**
Tetanus vaccination or booster according to status, and wound care after extraction.

**Lifestyle**
Closed footwear, cemented or covered floors, regular foot inspection, and community control including treatment of animals and use of insect repellents.

## Complications

- Bacterial superinfection, abscesses, cellulitis and lymphangitis
- Tetanus in unvaccinated people
- Nail loss, toe deformity, difficulty walking and chronic pain
- Tissue destruction in wound or cavitary myiasis
- Sepsis and gangrene in severe, neglected cases

## Prognosis

Excellent after complete removal, with healing in days to weeks. Reinfestation is common in endemic communities unless living conditions improve.

## Prevention

- Wear closed shoes and seal or cover earth floors
- Inspect feet daily in endemic areas and control infested animals
- Use repellents and mosquito protection, and cover wounds

## Test yourself

Think of the answer, then tap the question to see it.

## What causes tungiasis and where on the body are lesions typical?

The female sand flea Tunga penetrans; around and under the toenails, between the toes and on the heel.

## What is the typical lesion of tungiasis?

A white nodule with a central black dot (the flea's rear opening).

## Which fly causes furuncular myiasis in Latin America and how do its eggs reach the skin?

The human bot fly Dermatobia hominis; its eggs are carried by mosquitoes or other flies.

## What simple technique helps extract a bot-fly larva?

Occlude the central pore (for example with petrolatum) so the larva moves up for air and can be removed.

## Which vaccine status should be checked in both conditions?

Tetanus.

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## Related conditions

- [Cutaneous larva migrans](https://durgical.com/en/conditions/cutaneous-larva-migrans/)
- [Tetanus](https://durgical.com/en/conditions/tetanus/)
- [Cellulitis of the leg](https://durgical.com/en/conditions/cellulitis-of-the-leg/)
- [Abscess, furuncle and carbuncle](https://durgical.com/en/conditions/abscess-furuncle-and-carbuncle/)
- [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/)
- [Scabies](https://durgical.com/en/conditions/scabies/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Tungiasis](https://www.who.int/news-room/fact-sheets/detail/tungiasis) (World Health Organization, 2026); [Tungiasis](https://www.cdc.gov/dpdx/tungiasis/index.html) (Centers for Disease Control and Prevention (CDC), 2026); [Myiasis](https://www.cdc.gov/dpdx/myiasis/index.html) (Centers for Disease Control and Prevention (CDC), 2026).

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Source: https://durgical.com/en/conditions/tungiasis-and-furuncular-myiasis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/tungiasis-and-furuncular-myiasis/