Tungiasis and myiasis

Tungiasis, myiasis, and cutaneous larva migrans (CLM) are the three skin infestations a dermatology candidate must be able to separate at sight. They share a tropical geography and a returning-traveller presentation, but their biology — and therefore their treatment — diverges sharply. Tungiasis is a flea that burrows into the skin and must be dug out. Myiasis is a fly larva that is already in the skin and must be coaxed out. CLM is a hookworm that wanders under the skin and is killed by anthelmintics rather than extracted. Confusing the three loses marks and mistreats the patient: incising a botfly nodule releases the larva into the wound, while curetting a CLM track yields nothing.[1][4][10]

All three belong to the broader family of ectoparasitoses — organisms that live on or in the superficial skin — alongside scabies (Sarcoptes scabiei), pediculosis (lice), and tick infestation. This topic covers tungiasis and myiasis as the primary focus, with CLM as the key differential, and ends with an ectoparasite comparison table that anchors the board answer. [1]

Overview & Definitions

Tungiasis is an inflammatory skin disease caused by the gravid female sand flea Tunga penetrans (and rarely T. trimamillata), which burrows head-first into the stratum corneum of its host, feeds on dermal blood, swells to the size of a pea, expels eggs through a posterior opening, and then dies in situ. The flea does not leave the host during the parasitic phase; it must be physically removed. The disease is endemic across the tropics and is recognised by the World Health Organization as a neglected tropical disease in endemic countries.[1][3][10]

Myiasis (from the Greek myia, fly) is the infestation of living or dead vertebrate tissue by the larvae (maggots) of two-winged flies (order Diptera). It is classified by the anatomical site of infestation and, within the skin, by the behaviour of the larva. The clinical importance of myiasis lies in distinguishing furuncular disease (a single larva in a boil-like lesion, removable at the bedside) from wound/cavitary disease (many larvae in neglected tissue, needing debridement) and from rare but dangerous nasopharyngeal, aural, and ophthalmic forms.[4][6]

Cutaneous larva migrans (CLM), the most common tropically acquired skin disease in returning travellers, is a creeping eruption produced when animal hookworm larvae (classically Ancylostoma braziliense of dogs and cats) penetrate human skin but cannot complete their life cycle in an abnormal host, so they wander aimlessly in the epidermis until they die weeks to months later. Humans are a dead-end host; the parasite never reaches the gut, so the disease is self-limiting but intensely pruritic.[7][8]

Classification

Myiasis and CLM each have a classification the examiner tests deliberately. For myiasis, the clinically useful axis is anatomical (where the larva lives) cross-referenced with behavioural (obligate, facultative, or accidental parasite). For CLM there is one entity with a defined set of mimics. [1]

A second distinction the examiner rewards is between obligate myiasis flies (which require a host to complete the life cycle — Dermatobia hominis, Cordylobia anthropophaga, Cochliomyia hominivorax) and facultative myiasis flies (which normally lay eggs in carrion or decaying matter but opportunistically infest wounds — Lucilia, Calliphora, Sarcophaga).[4][9]

Epidemiology & Risk Factors

Two epidemiological pearls recur in exams. First, Dermatobia hominis does not lay its eggs directly on human skin: it captures a blood-feeding mosquito (or other arthropod) and glues its eggs to the vector's abdomen — a process called phoresy — so that the eggs hatch and larvae burrow into the human when the mosquito takes a blood meal. Second, Cordylobia anthropophaga lays eggs on soiled clothing and shaded sandy soil, not on the body; the larvae hatch on contact with warm skin and penetrate within hours, which is why ironing clothes is a specific preventive measure in endemic Africa.[4][5][9]

Pathophysiology

Tungiasis — the burrowing gravid flea

The gravid female T. penetrans (only 1 mm before infestation) jumps onto a barefoot host and rapidly burrows into the stratum corneum using its mouthparts, advancing until its abdomen is flush with the skin surface. Over the next 7 to 14 days the flea feeds on dermal blood and enlarges enormously — the abdomen swells to the size of a pea (hypertrophy of about 2000-fold) while the head remains buried deep in the dermis. The posterior cone — bearing the respiratory, excretory, and genital openings — is the only part that stays flush with the skin surface, and it is this dark ring of chitin that produces the pathognomonic black dot in the centre of the nodule.[3][10]

Over the next 7 to 10 days the flea expels 150 to 200 eggs through the posterior opening onto the ground, where they hatch into free-living larvae, pupate, and emerge as adult fleas to repeat the cycle. After egg expulsion the flea dies in situ and is either extruded or calcified in the dermis. The surrounding erythema, pain, and pruritus reflect a foreign-body and inflammatory reaction to the embedded arthropod and its faecal material; the risk of secondary bacterial infection is high because the lesion is an open portal to the dermis.[3]

Furuncular myiasis — the larva in a breathing pore

In Dermatobia hominis infestation, the first-instar larva hatches on the skin from a mosquito-borne egg and penetrates the dermis through the mosquito bite wound or a hair follicle. Inside the dermis the larva moults to the second and third instar, excavating a cavity (the furuncle) and anchoring itself with rows of cuticular spines that make manual extraction difficult and painful. Crucially, the larva's posterior spiracles (its respiratory openings) align with the central punctum on the skin surface, so it breathes atmospheric air through this opening. This anatomy is the key to treatment: occluding the punctum cuts off the oxygen supply and forces the larva to surface, after which it can be extracted with forceps.[4][5]

The surrounding inflammation produces the classical furuncle-like nodule with erythema, tenderness, and a serosanguineous or purulent discharge from the punctum; patients often report a sensation of movement or a sharp pricking pain within the lesion as the larva feeds. Rupturing the larva in situ provokes a severe foreign-body granulomatous reaction and secondary infection, so intact extraction is the aim.[5][6]

Wound myiasis — opportunistic colonisation

Facultative calliphorid flies are attracted to the odour of decaying tissue and exudate in chronic wounds, ulcers, and body orifices of debilitated patients. Eggs are laid in clusters; the larvae (screwworms or maggots) feed on necrotic tissue and serous exudate, and in obligate species such as Cochliomyia hominivorax they also invade living tissue, causing extensive destruction. Wound myiasis is therefore a marker of neglected nursing care as much as of parasitism.[4][9]

Cutaneous larva migrans — the lost hookworm

Animal hookworm larvae in dog or cat faeces hatch on warm, moist sand and penetrate the bare human skin of a beach-goer. In the natural canine or feline host they would migrate via the bloodstream to the intestine, but in the human abnormal host they cannot penetrate the basement membrane of the epidermis. They therefore wander laterally in the stratum granulosum/spinosum, advancing 1 to 2 cm per day and laying down the track of inflammation, pruritus, and serpiginous erythema that gives the disease its name. Because the larvae cannot complete their life cycle, they eventually die — but only after weeks to months of misery and a high risk of excoriation and secondary bacterial infection.[7][8]

Clinical Presentation

Tungiasis

The classic lesion is a solitary, firm, whitish-yellow nodule, 5 to 10 mm across, with a central dark punctum (the black dot), surrounded by a variable rim of erythema and scaling. The site is almost always a weight-bearing or contact area of the foot: the plantar surface, the toes, the periungual folds, the interdigital webs, and the heels. Lesions outside the feet (hands, elbows, buttocks, scrotum) occur when the host has been sitting or lying on infested ground. Pain, tenderness, and pruritus are the dominant symptoms; itch is especially prominent early and pain late as the flea enlarges and stretches the dermis.[1][3]

In hyperendemic communities the disease is polymorphic and recurrent: dozens of lesions, deformed and lost toenails, difficulty walking, fissuring, lymphangitis, and abscess formation. The most feared acute complications are secondary bacterial infection (Streptococcus pyogenes, Staphylococcus aureus), ascending lymphangitis, abscess, sepsis, tetanus, and even gas gangrene in unvaccinated children.[3][10]

Furuncular myiasis

The patient — often a returning traveller or a rural child in the neotropics — presents with one or more furuncle-like nodules on an exposed site (scalp in children; face, neck, shoulders, arms, or legs in adults) that have failed to respond to antibiotics and that are accompanied by a sharp, intermittent lancinating pain ("something moving"). Closer inspection reveals a central punctum from which serosanguineous fluid may weep, and occasionally the black or yellow posterior tip of the larva is visible at the pore, bobbing up to breathe. The surrounding skin is erythematous and oedematous; regional lymphadenopathy and low-grade fever may be present. Lesions are typically solitary with Dermatobia and multiple with Cordylobia (the tumbu fly), which may lay many eggs on soiled clothing.[5][6][9]

Wound myiasis

The presentation is a neglected, malodorous wound, ulcer, or body cavity teeming with maggots in a debilitated patient. Larvae may be visible in the wound bed or expressed on dressing changes. Surrounding tissue destruction, erythema, and a pungent odour are typical. The clinical emergency is to exclude invasion of deeper structures, the orbit, the middle ear, or the paranasal sinuses.[4][9]

Cutaneous larva migrans

The hallmark is an intensely pruritic, serpiginous (snake-like), erythematous, slightly raised track that migrates 1 to 2 cm per day as the larva advances through the epidermis. The track is tortuous and may be several centimetres long, with the leading edge (the larva) at the advancing tip and the trailing segment fading as it heals. Sites are determined by contact with contaminated sand: the feet (most common), buttocks ('beach bum'), thighs, and abdomen. Multiple tracks occur in heavy infestation. Bacterial superinfection from scratching, folliculitis, and (rarely) a Löffler-like syndrome of transient pulmonary infiltrates with eosinophilia have been reported.[7][8]

The incubation is short — pruritus usually begins within hours to a few days of beach exposure, which is why CLM is the single most common dermatological diagnosis in travellers presenting in the first one to two weeks after return. Untreated, the disease is self-limiting: the larva cannot complete its life cycle in the human dead-end host and dies after weeks to months, but the intense itch, sleep loss, and risk of impetiginisation make active treatment preferable to watchful waiting. Vesiculobullous and follicular variants are described but uncommon.[7][8]

Differential Diagnosis

The differentials overlap because all three conditions produce a nodule, a track, or a chronic wound. The discriminator is the morphology of the punctum and the movement, combined with travel and exposure history. [1]

[1]

Two distinctions reward candidates. First, larva currens of strongyloidiasis moves much faster (5 to 10 cm per day, often perianal and recurrent from autoinfection) than CLM, and is urticarial rather than serpiginous-scaly. Second, migratory myiasis (from Gasterophilus or Hypoderma) produces a creeping eruption indistinguishable at sight from CLM, but the track is longer and less pruritic, the patient has animal (horse/cattle) exposure, and the larva is a fly larva — extractable rather than anthelmintic-responsive.[4][7]

Clinical & Bedside Assessment

Diagnosis is overwhelmingly clinical — the morphology plus the travel history is the test. Bedside steps that add value: [1]

• Inspect under good light and magnification (dermoscopy or a loupe). For furuncular myiasis, dermoscopy may show the white-yellow body of the larva with dark posterior spiracles (the "respiratory spikes") centred on the punctum; direct visualisation of rhythmic movement of the larval spiracles clinches the diagnosis.
• For tungiasis, the target appearance — a whitish nodule with a dark central punctum on a periungual toe — is pathognomonic. Note the number and depth of lesions, the presence of pus, lymphangitis, or systemic signs.
• For CLM, mark the leading edge with a skin-marking pen and review in 24 hours: measurable migration of the track confirms the diagnosis and excludes fixed mimics (tinea, granuloma annulare).
• Always take a full travel, occupational, animal, and footwear history, and check tetanus vaccination status in any patient with a skin infestation.[1][4][8]

Investigations

Investigations are usually unnecessary, but they have specific roles: [1]

A normal eosinophil count does not exclude CLM or myiasis; eosinophilia, when present, is supportive but never the basis of the diagnosis.[4][7]

Management — Resuscitation

Most ectoparasite infestations are managed electively, but three situations demand immediate action: [1]

1. Severe secondary bacterial infection (cellulitis, lymphangitis, abscess, sepsis) complicating tungiasis — take blood cultures, give empirical intravenous antibiotics against Streptococcus pyogenes and Staphylococcus aureus (e.g., intravenous flucloxacillin, or vancomycin if MRSA is suspected), and review tetanus status with tetanus toxoid and immunoglobulin as indicated.
2. Cavitary myiasis involving the nasopharynx, ear, orbit, or a deep wound in a debilitated patient — this is a surgical and ENT emergency requiring removal of all larvae under anaesthesia, debridement of necrotic tissue, and systemic antibiotics; Cochliomyia hominivorax (New World screw-worm) invades living tissue and can cause catastrophic destruction.[9]
3. Anaphylaxis to rupture of a larva is rare but reported during extraction of botfly larvae; have adrenaline and resuscitation equipment available when extracting deep or multiple lesions.[4]

Management — Definitive & Stepwise

Tungiasis: extract the flea en bloc

[1]

The principle is mechanical completeness. A partially extracted flea continues to cause inflammation and superinfection, and retained chitin provokes a chronic granuloma. In endemic communities, mass drug administration with ivermectin and topical agents has been studied as a public-health measure, and environmental insecticide spraying, concrete floors, and footwear are the structural interventions that actually reduce transmission.[3][10]

Furuncular myiasis: asphyxiate then extract

The aim is to deprive the larva of oxygen so it migrates to the surface, after which it can be gripped and extracted intact. Rupturing the larva in situ must be avoided because the cuticular spines anchor it and the contents provoke a severe foreign-body reaction.[5][6]

[1] [1]

Wound myiasis: debride and irrigate

Management is mechanical: expose the wound, remove all larvae with forceps under good lighting and irrigation (saline, dilute povidone-iodine, or ether/chloroform if larvae are deep), debride necrotic tissue, and dress the wound. Topical ivermectin and oral ivermectin have a role in extensive infestation. Address the underlying cause — neglected wound care, debility, incontinence, pressure relief — because recurrence signals a failure of basic nursing attention.[4][9]

Cutaneous larva migrans: anthelmintics, not extraction

CLM is not treated by extracting a larva — the larva is microscopic and cannot be grasped. Treatment is an oral anthelmintic: [1]

• Oral albendazole 400 mg daily for 3 to 5 days (first-line; safe in adults and children over 2 years).
• Oral ivermectin 200 mcg/kg single dose, repeated once after 7 to 14 days for extensive or relapsing disease.
• Topical thiabendazole 10 to 15% two to three times daily for 5 to 7 days — for localised, uncomplicated disease, pregnancy, or young children where oral therapy is avoided.
• Cryotherapy of the leading edge is less effective and risks ulceration; it is reserved for a single persistent track.[7][8]

Specific Subtypes & Scenarios

Complications & Pitfalls

The single most common procedural error in exams and in practice is incising a furuncular myiasis lesion. A botfly nodule looks like a furuncle, but incising it releases the larva, contaminates the wound, and leaves the spined larva behind. The correct manoeuvre is occlusion then extraction.[5][6]

Prognosis & Disposition

With correct treatment all three conditions have an excellent prognosis. Simple tungiasis heals within days of complete extraction; furuncular myiasis heals in 1 to 2 weeks after intact larval removal; CLM resolves within days of an effective anthelmintic. The prognosis deteriorates in endemic poverty — recurrent tungiasis in resource-poor communities causes chronic disability, deformity, lost schooling, and (rarely) death from tetanus or sepsis — and in neglected wound myiasis in the debilitated, where the underlying frailty drives outcome.[3][10]

Most patients can be discharged after definitive treatment with safety-net advice: return if there is spreading erythema, increasing pain, fever, or pus. In returning travellers, screen for co-acquired tropical infections (malaria, dengue, Strongyloides, schistosomiasis) that may share the same exposure. [1]

Special Populations

Evidence, Guidelines & Regional Differences

There is no single global guideline; practice draws on WHO public-health guidance for tungiasis, travel-medicine consensus for furuncular myiasis and CLM, and national dermatology guidance for management in non-endemic returning travellers. [1]

[1]

The principal controversy is the drug choice for CLM: oral ivermectin (one dose, convenient) versus oral albendazole (3 to 5 days, well tolerated, globally available). Both are effective; the choice often depends on availability, pregnancy status, and patient age. For tungiasis, the structural interventions (footwear, concrete floors) are the only measures shown to reduce community burden.[3][8][10]

Scabies vs Other Ectoparasites — The Board Comparison

Because the assignment and the frontmatter link tungiasis and myiasis to the wider ectoparasite family, the examiner will frequently ask for a distinguishing table. The five ectoparasitoses a candidate must separate are scabies, pediculosis, tungiasis, myiasis, and CLM.[11]

[1]

The must-not-miss message: a painful furuncle on the scalp of a returning traveller from the Americas that has not responded to antibiotics is a botfly until proven otherwise; a black dot on a barefoot child's toe is tungiasis; a wandering itchy track after a beach holiday is CLM; and intense nocturnal itch shared by household contacts is scabies.[1][4][7][11]

Prevention

Exam Pearls

Red Flags

Exam application bank (NEET-PG / INICET)

One-line answer

Tungiasis: gravid female Tunga penetrans (sand flea) burrows into the stratum corneum of the feet → a white-yellow nodule with a central black dot (the flea's posterior respiratory cone); endemic Caribbean/sub-Saharan Africa/South America; treatment is sterile needle/curette extraction en bloc plus antiseptic and tetanus prophylaxis, with oral ivermectin 200 mcg/kg for heavy infestation. Myiasis: infestation of living tissue by dipteran fly larvae — furuncular (Dermatobia hominis botfly, Central/South America, painful nodule with a breathing pore; Cordylobia anthropophaga tumbu fly, sub-Saharan Africa), wound (Lucilia/Calliphora/Cochliomyia in neglected wounds), migratory, and nasopharyngeal; treatment is occlude the pore with petrolatum/bacon to asphyxiate the larva → extract with forceps, plus debridement for wound myiasis. Cutaneous larva migrans: dog/cat hookworm larvae ( [1]

Worked stems (answer without another resource)

Stem 1 — Classic presentation. Map symptoms to mechanism; name the first investigation and first treatment step with dose/route if drug therapy is standard. [1]

Stem 2 — Unstable / complicated. List red flags that force immediate resuscitation, theatre, ICU, antidote, or reperfusion — and what you do in the first 15 minutes. [1]

Stem 3 — Atypical group. Elderly, pregnancy, child, or immunocompromised: how presentation and thresholds change. [1]

Stem 4 — Differential trap. Name the three closest mimics and one discriminator for each. [1]

Stem 5 — Disposition. Who goes home with safety-netting, who is admitted, who needs HDU/ICU/theatre, and what follow-up is mandatory. [1]

Rapid viva checklist

1. Definition + classification
2. Pathophysiology chain
3. Bedside signs / criteria
4. Score with exact components (if any)
5. Emergency bundle
6. Definitive therapy with doses
7. Complications of disease and of treatment
8. Special populations
9. Guideline/trial name if classic
10. Three exam traps

Coverage self-check

If you cannot answer any stem above from this page alone, re-read the matching section — the page is intended to be self-sufficient for final-prof and NEET-PG/INICET questions on Tungiasis and myiasis.

References

1. [1]Coates SJ, Thomas C, Chosidow O, et al. Ectoparasites: Pediculosis and tungiasis J Am Acad Dermatol, 2020.PMID 31306729
2. [2]Cestari TF, Pessato S, Ramos-e-Silva M. Tungiasis and myiasis Clin Dermatol, 2007.PMID 17350494
3. [3]Heukelbach J. Tungiasis Rev Inst Med Trop Sao Paulo, 2005.PMID 16553319
4. [4]Francesconi F, Lupi O. Myiasis Clin Microbiol Rev, 2012.PMID 22232372
5. [5]Solomon M, Lachish T, Schwartz E. Cutaneous Myiasis Curr Infect Dis Rep, 2016.PMID 27443558
6. [6]McGraw TA, Turiansky GW. Cutaneous myiasis J Am Acad Dermatol, 2008.PMID 18485982
7. [7]Leung AKC, Barankin B, Hon KLE. Cutaneous Larva Migrans Recent Pat Inflamm Allergy Drug Discov, 2017.PMID 28078983
8. [8]Palaniappan V, Gopinath H, Karthikeyan K. Cutaneous larva migrans Clin Exp Dermatol, 2026.PMID 40795202
9. [9]Calvopina M, Ortiz-Prado E, Castañeda B, et al. Human myiasis in Ecuador PLoS Negl Trop Dis, 2020.PMID 32084134
10. [10]Heukelbach J, Feldmeier H. Ectoparasites--the underestimated realm Lancet, 2004.PMID 15032237
11. [11]Galván-Casas C, Salavastru C, Ortiz-Álvarez J. Scabies and other ectoparasitoses Clin Exp Dermatol, 2026.PMID 40567146