Tungiasis and furuncular myiasis !

Tungiasis (sand flea, «nigua») and furuncular myiasis (bot-fly larva, «nuche») are skin infestations common in rural Colombia that cause painful nodules.

Updated 2026-11-01

Structures involved

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Microorganisms that cause it

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

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.

Add to my cards (5)

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

Sources: Tungiasis (World Health Organization, 2026); Tungiasis (Centers for Disease Control and Prevention (CDC), 2026); Myiasis (Centers for Disease Control and Prevention (CDC), 2026).

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Representative model, for educational purposes only.

Skin highlighted on the Durgical 3D model