Cutaneous larva migrans and other skin parasites

• Cutaneous larva migrans (CLM) is the creeping, very itchy eruption caused when animal hookworm larvae from contaminated soil enter human skin; humans are a dead-end host and the larvae cannot complete their life cycle.
• Scabies is an infestation with the human itch mite Sarcoptes scabiei, producing burrows in skin folds and intense night-time itch; lice are surface feeders on blood and leave nits attached to hairs.
• Tungiasis is the embedded sand flea Tunga penetrans, producing a painful, often single nodule, usually on the foot.
• Across all of these, a travel or exposure history, skin examination, and topical or oral antiparasitics are the backbone of care, and close contacts must be treated at the same time.
• Albendazole and ivermectin are the standard oral agents for CLM, while permethrin 5% cream and oral ivermectin are the standard first-line agents for scabies.^[5]

By the end of this page you should be able to:

1. Define cutaneous larva migrans, scabies, pediculosis, and tungiasis, and place them among the common parasitic skin diseases.
2. Explain the life cycle and mechanism that produces the creeping eruption of CLM, and distinguish CLM from larva currens.
3. Take a targeted exposure and travel history and recognise the key examination findings for each condition.
4. Plan first-line and alternative treatment for CLM, scabies, pediculosis, and tungiasis, with doses, duration, and safety notes.
5. Recognise crusted scabies, widespread infestation, and other red flags, and know when to refer.
6. Advise patients on prevention, contact management, and special groups including pregnancy and young children.

Scabies is an infestation of the epidermis by the human itch mite Sarcoptes scabiei var. hominis; the mite burrows and lays eggs, producing the characteristic burrows and a delayed hypersensitivity itch. Pediculosis is infestation by lice that feed on human blood; the usual species are Pediculus humanus capitis (head louse), Pediculus humanus corporis (body louse), and Pthirus pubis (pubic or crab louse). Body lice live in clothing and bedding rather than on the skin. Tungiasis is the infestation in which the fertilised female sand flea Tunga penetrans embeds in the skin, most often the sole of the foot, and enlarges as it matures. ^[8]

Classification matters because the four conditions need different drugs even though all cause itch:

• CLM and the underlying hookworms are nematodes; oral antihelminthics (albendazole, ivermectin) are used.
• Scabies and lice are arthropods; scabicides and pediculicides are used.
• Tungiasis is a flea; management centres on physical removal and topical or systemic antiparasitics rather than the scabicides used for mites.

Clinicians commonly cross-check these conditions against the standard references and guidelines (StatPearls, AAD, BAD, NICE Clinical Knowledge Summaries, and CDC); where schedules differ, especially for crusted scabies, local formularies and infection-control teams take precedence.

Sporotrichosis, although it appears among the parasitic skin infections of the same pages, is a subcutaneous fungal infection caused by Sporothrix species, usually after a plant or soil injury or a cat scratch. It is not a parasite and should not be treated with antihelminthics.^[7]

CLM is a disease of tropical and subtropical regions, especially Africa, South America, the Far East, and the South Pacific; in Europe it is most often seen in returned travellers, and cases of CLM occurred in about 2 to 70% of tourists who returned from endemic areas, with the higher figure reflecting selected high-risk exposures such as time on beaches.^[4] Risk factors are bare skin contact with moist, sandy or soil environments contaminated by dog or cat faeces: beaches, sandpits, gardens, and resort surroundings, plus owning or living close to stray dogs and cats. One series found that stray animals were the source of contaminated soil in tropical urban settings.^[4]

Scabies occurs worldwide and spreads by prolonged direct skin-to-skin contact and, less often, by sharing clothing or bedding. Households, care homes, prisons, schools, and crowded conditions are the setting, and asymptomatic contacts are common. The World Health Organization has recognised scabies as a neglected tropical disease because of its burden in resource-limited settings.

Head lice spread most often by head-to-head contact and are common in school-aged children; they are not a marker of poor hygiene. Body lice are more common where clothing is not changed or washed regularly and can carry rickettsial and other infections. Tungiasis is common in parts of sub-Saharan Africa, South America, and the Caribbean and clusters among people who walk barefoot or wear open footwear; many cases are never diagnosed or reported.^[8]

The cause of CLM is the accidental penetration of human skin by animal hookworm larvae. The usual culprits are dog hookworms (Ancylostoma braziliense, A. caninum, A. ceylanicum) and cat hookworms (A. braziliense, A. ceylanicum), with Uncinaria stenocephala also implicated.^[4] Moist sand or soil contaminated by animal faeces carries the infective larvae, which can survive 3 to 4 weeks in the soil and penetrate skin on contact.^[4] No modifiable human risk factor other than exposure exists; prevention is behavioural.

For scabies, the female mite burrows into the stratum corneum and deposits eggs; re-infestation from untreated contacts is the common cause of recurrence. The established risk factors are crowding and skin contact, not cleanliness. For lice, the risk factor is simply contact with an infested person or their headwear and bedding; lice move slowly and cannot jump or fly. Tungiasis follows bare-foot exposure to soil or floor cracks containing flea eggs.

In CLM, the larvae enter through hair follicles or skin cracks, then migrate in the narrow space between the epidermis and the germinal layer of the dermis. Because zoonotic hookworm larvae lack the enzymes to penetrate deeper into the human dermis, they are confined to this shallow plane and produce the raised, serpiginous, intensely itchy track. The track is usually 1 to 5 cm long, and migration advances at about 1 to 2 cm per day (occasionally quoted as 1 to 3 cm per day in clinical case series).^[4] Secondary bacterial infection from scratching is common and can produce a more angry, exudative picture.

Larvae may enter a dormant state in subcutaneous tissue and reactivate weeks or even months later, producing new tracks; this is the reason some patients have a relapsing course despite initial treatment.^[4] Humans are a dead-end host, so the eruption is self-limiting: the larvae usually die within 5 to 6 weeks of skin entry even without treatment.^[1]

Scabies pathophysiology is different. The mite burrows and lays eggs; larvae hatch and mature on the skin. Itching is largely a type IV hypersensitivity reaction to mite products and eggs, which is why it appears weeks after a first infestation and within days in a previously sensitised person. In crusted (Norwegian) scabies, impaired immunity allows enormous mite numbers to accumulate, producing thick hyperkeratotic crusts with extreme infectivity.

Lice feed on blood several times a day and inject saliva; itch and papules are hypersensitivity reactions. Body lice live and lay eggs in seams of clothing, leaving only to feed. A female head louse cements each egg (nit) to a hair shaft. Tunga penetrans embeds head-down, feeds on blood, expels eggs through an opening at the skin surface, and the pregnant flea swells to a pea-sized nodule with a characteristic central black dot.

CLM symptoms depend heavily on where larvae entered. Patients report an extremely itchy, sometimes burning rash that worsens at night, with a visible worm-like or snake-like trail that seems to move day by day; a minority report only a papulovesicular rash at the inoculation site. The minimum useful history questions are:

• recent travel to tropical or subtropical regions (beaches, sand, soil), including the destination and dates;
• walking barefoot, sitting or lying on sand, or gardening;
• whether pets (or stray animals) were present;
• how fast any "track" is moving and whether new tracks have appeared weeks later (reactivation of dormant larvae);
• what treatment was tried and whether it helped.

Scabies presents with intense generalised itch that is worse at night and after a hot bath, affecting the whole body apart from the head and neck in adults; infants and older adults may have scalp and facial involvement. Burrows are often not visible because of scratching and secondary eczema. Family or household contacts are usually itchy at the same time. Lice cause tickling, itching, or a crawling sensation; head lice may be noticed because of nits or impulse scratching. Tungiasis presents as a painful or pruritic nodule, most often on the toes or soles, with a central dark dot, in a person who has walked barefoot in an endemic area.

A full mucocutaneous history, comorbidities (immunosuppression), medications, pregnancy, and occupation should be recorded for every patient, because they change management and the risk of crusted scabies.

CLM. Look for linear, raised, serpiginous tracks, usually 1 to 5 cm long, with a reddish, slightly oedematous, sometimes vesicular advancing end; the track advances 1 to 2 cm per day.^[4] Bullous (blistering) CLM is uncommon but recognised. Scattered papules or pustules from secondary bacterial infection are common. Sites are usually the feet, legs, buttocks, thighs, and hands. Fresh tracks are most visible after a hot bath or shower. A magnifying lens helps; dermoscopy is not required. There is no central dark dot (this separates CLM from tungiasis). The exam is usually otherwise normal and blood tests are usually normal.

Scabies. Inspect the whole body with good lighting. Look for burrows (tiny, slightly raised, silver-coloured lines ending in a tiny black dot, the mite), with a deltascopic triangle visible on dermoscopy. Predilection sites are the finger webs and sides of the fingers, palms, wrists and forearms, axillae, groin and genitals, breasts and nipples, waistline, and feet and ankles; in infants and older adults the head, neck and palms can be involved. Secondary eczema, excoriation, pustules and impetigo are common. Crusted scabies shows thick, hyperkeratotic, crusted, yellow plaques on hands, feet, elbows and knees, with minimal itch despite enormous mite numbers. ^[3]

Lice. For head lice, separate the hairs with fine-toothed comb sticks from the scalp outward, especially at the nape and behind the ears, looking for live, moving lice and for nits cemented to hair shafts; nits close to the scalp are the most likely to be viable. Body lice are found in clothing seams rather than on the skin; examine the seams of underclothing. Pubic lice are short, crab-like lice attached to coarse body hair in the pubic region, axillae, chest, or eyelashes (phthiriasis palpebrarum in young children can indicate abuse and needs careful assessment).

Tungiasis. A small papule evolves into a whitish or yellowish nodule with a central black dot (the flea's posterior segments), usually on the toes, sole, or heel; it can be painful, especially if secondarily infected. Multiple lesions can occur with heavy exposure.

CLM is diagnosed clinically from the appearance and the epidemiological history. No blood test confirms it; eosinophilia is sometimes present but is not consistent, and stool examination is not useful because humans are a dead-end host. Scabies is likewise clinical in most cases; the AAD describes the diagnosis as a careful skin examination, with confirmation by painless skin scraping showing mites or eggs under the microscope, which is useful for atypical cases (for example in immunosuppression).^[2] Pediculosis is diagnosed by finding live lice or viable nits on examination and combing. Tungiasis is diagnosed by the characteristic lesion plus exposure.

A dermatoscope is a useful office tool for scabies burrows and for distinguishing tungiasis from CLM. Skin scrapings for microscopy, bacterial culture of secondary infection, and biopsy are used only for atypical or refractory cases. In immunocompromised patients or any patient with suspected crusted scabies, a low threshold for microscopy or biopsy is appropriate.

There is no widely accepted scoring system or severity stage for CLM; the distinction that changes management is single versus extensive disease and the presence of complications such as folliculitis. The closest practical stratification is: localised CLM (small number of tracks), extensive CLM (numerous, multiple limb or truncal tracks), and chronic/reactivated CLM (dormant larvae releasing after the first course of treatment). Extensive or follicular disease usually needs systemic rather than topical therapy.

For scabies, the important classification is classic (typical distribution, few mites) versus crusted/Norwegian (hyperkeratotic, thick crusts, enormous mite burden, highly contagious) and institutional outbreak settings; crusted scabies drives the need for combined oral and topical therapy and repeated dosing. For lice, the classification is head, body or pubic (each has a different treatment site and practical focus). Tungiasis is classified as simple (small, uninfected nodule) versus complicated (secondary infection, nail or digital involvement, deformity), which foretells complications.

A useful bedside differential check is the speed of migration: larva currens, the skin form of strongyloidiasis, advances at 5 to 10 cm per hour, whereas CLM advances at about 1 to 2 cm per day; both are serpiginous, raised, and intensely pruritic.^[4]

• Any patient with suspected crusted scabies in a household, care home or school needs immediate recognition, isolation of cases, and simultaneous treatment of all contacts, because a single case can seed an outbreak.
• Secondary bacterial infection, especially cellulitis, should be treated with appropriate antibiotics alongside the antiparasitic.
• Ocular involvement (lice on lashes in young children), systemic symptoms with fever, or immune compromise requires urgent referral.
• A patient with a creeping eruption and systemic symptoms, or one who is immunosuppressed, should be assessed for larva currens due to Strongyloides, which has different treatment.

CLM is self-limiting because the larvae die after 5 to 6 weeks, but treatment shortens symptoms, reduces transmission and scarring, and prevents secondary infection. Topical agents that require targeting the individual larva (freeze-blasting, topical thiabendazole) are of limited value because the larva's location is usually uncertain; they are best reserved for very limited disease. Systemic antihelminthics are the standard.

• Albendazole 400 mg by mouth once daily for 3 to 7 days in adults.^[1]
• In children older than 2 years, albendazole 400 mg by mouth once daily for 3 days; albendazole is contraindicated in children younger than 2 years.^[1]
• Ivermectin 200 mcg/kg by mouth as a single dose in adults and in children who weigh more than 15 kg.^[1]
• Severe or relapsing CLM, or disease with folliculitis, may need additional doses.^[1]
• Younger children (younger than 2 years or under 15 kg) are usually treated with topical preparations rather than systemic drugs.^[1]
• WHO guidance allows albendazole in mass prevention campaigns from the age of 1 year and ivermectin from about 90 cm height (reached by roughly half of boys at 28 months and half of girls at 30 months), always at an appropriate dose.^[1]

Relapses after the first course are not uncommon because of dormant larvae. A practical approach to relapse is a second full course, or combining albendazole and ivermectin, which has been used for refractory CLM. In one family of three returning travellers, treatment (pyrantel followed by two 3-day courses of albendazole 400 mg) was followed by reactivation of dormant larvae at day 28 to 33 and eventual full resolution by two months.^[4]

In the United States, CDC guidance lists first-line therapy for classic scabies as either permethrin 5% cream (FDA-approved from 2 months of age, applied to all skin from the neck down, washed off after 8 to 14 hours, with one application often sufficient and two or more applications about a week apart when needed) or oral ivermectin 200 mcg/kg per dose (two doses with food, 7 to 14 days apart); topical permethrin and oral ivermectin have similar cure rates.^[5] The AAD adds that permethrin 5% is approved for patients from 2 months of age and for pregnant women, and lists crotamiton 10%, benzyl benzoate 25% (for crusted scabies), spinosad 0.9% (from 4 years), sulfur 5% to 10% (usable in infants younger than 2 months), and lindane 1% (reserved for treatment failure).^[2] The United Kingdom practice (reflected in BAD patient guidance and the formularies based on NICE Clinical Knowledge Summaries) uses permethrin 5% cream first line, applied to all skin including the neck, scalp and face (avoiding the eyes), left on for at least 12 hours and repeated after 7 days, with malathion as an alternative where available, and oral ivermectin for selected or refractory cases.^[3]

Application details matter. Mites may be anywhere on the skin, so the product must cover all skin, not just the itchy parts, with particular attention to between the fingers and toes, the palms, genitals, skin behind the ears, nipples, and under the nails. Treatment is applied at night to cool, clean, dry skin, left for at least 12 hours, and the whole process repeated 7 days later so that the mite and the eggs are both destroyed.^[3] Clothing, bedding and towels should be washed, or sealed in bags for 3 days.^[3] Itching commonly continues for several weeks after successful treatment; the AAD notes that the skin should heal within 4 weeks, and persistence beyond that warrants re-examination.^[2] Contacts without symptoms must still be treated at the same time or re-infestation is likely.^[2][3]

Crusted scabies is treated with combined oral and topical therapy: CDC recommends ivermectin 200 mcg/kg per dose, given in three doses (days 1, 2, and 8), five doses (days 1, 2, 8, 9, and 15), or seven doses (days 1, 2, 8, 9, 15, 22, and 29) according to severity, together with whole-body permethrin 5% applied at least initially daily to every 2 to 3 days for the first 1 to 2 weeks, plus a keratolytic on days without permethrin, until crusting resolves.^[5]

Head lice. First-line options are over-the-counter topical pediculicides, but efficacy is reduced where resistance is common.^[6] CDC recommends pyrethrins with piperonyl butoxide (retreat 9 to 10 days later) for patients from 2 years of age, or permethrin 1% lotion (may retreat on day 9) for patients from 2 months of age; prescription alternatives include benzyl alcohol 5% lotion (repeat after 7 days, from 6 months), spinosad 0.9% (from 6 months, usually no retreatment), malathion 0.5% (from 6 years), and ivermectin 0.5% lotion (from 6 months). Oral ivermectin given as a single dose of 200 or 400 mcg/kg repeated in 9 to 10 days is effective against head lice, but should not be used in children under 15 kg or in pregnant women.^[6] Nit combing is always a sensible adjunct; repeated treatment with the same agent should not be given more than 2 to 3 times without success.^{[6] [1][5]}

Body lice are best treated by hot washing and hot drying (or ironing) of clothing and bedding, and by treating the person with the same pediculicides as for head lice; simply treating the skin without treating the garments fails. Pubic lice are treated with the same topical agents applied to the affected area; sexual partners within the preceding month should be treated, and a full sexually transmitted infection screen is appropriate because pubic lice are co-transmitted with other infections. Lashes can be treated with careful application of a bland ointment to smother the lice.

The embedded flea is best dealt with by surgical or sterile extraction with a sterile needle or forceps, with care not to rupture the flea, followed by cleaning and dressing. Killing the flea in situ with a drop of dimeticone or silicone oil, or by cryotherapy, and then extracting, has been reported to work. There is no single agent with the weight of evidence behind permethrin for scabies. Always exclude tetanus prophylaxis where indicated by local guidance. Trauma and secondary infection are the main reasons treatment of tungiasis matters; a simple nodule in an otherwise healthy person can still produce pain, difficulty walking and, if infected, abscess formation. Walking barefoot should stop until healed.

Non-drug measures are central to all of these conditions. For CLM, avoid bare skin exposure on potentially contaminated sand or soil, wear footwear and a barrier towel, and wash off soil or sand promptly; pets should be dewormed. For scabies and lice, hot-wash and hot-dry clothing, bedding and towels, or seal them in bags for a few days, and clean combs and hairbrushes.

For tungiasis, wear closed shoes and use environmental measures (sweeping and treating soil floors, rat and dog control). Education of the patient and contacts is as important as the prescription; written instructions on how to apply scabicide, and reminders to treat asymptomatic contacts, markedly improve cure rates.^[3]

• Albendazole and ivermectin are both adult doses taken by mouth; both are pregnancy category C in CDC labelling, so they should be used in pregnancy only if the benefit justifies the risk.^[1]
• Oral ivermectin (for scabies and lice) is taken with food for better bioavailability, and is not recommended in children under 15 kg or in pregnant women.^[5][6]
• For scabies, two permethrin applications about one week apart or two ivermectin doses 7 to 14 days apart are the standard regimens for classic disease; crusted disease needs repeated dosing.^[5]
• Monitor for treatment failure at 4 weeks and re-treat rather than escalate prematurely; persistent itch after cure is expected.^[2]

Surgery is not standard for CLM, scabies or lice. It matters for tungiasis (sterile extraction), for crusted scabies with hyperkeratosis (mechanical debridement of crusts to let medication penetrate), and for drainage of a secondary abscess. Cryosurgery is an option for thick keratotic lesions of sporotrichosis.^[7]

Re-examine after a few weeks, with a telephone check in between where local systems allow. For CLM, relapse is common because of dormant larvae and is treated with a further course. For scabies, confirm that contacts were treated and that compliance (correct application, adequate time, correct repeat) was good, because apparent failure is usually due to one of these rather than drug resistance. For head lice, re-treat at 9 to 10 days if live lice reappear before the eggs have cleared.^[6]

• Suspected crusted or Norwegian scabies, or an outbreak in an institution.
• Any patient who is immunosuppressed, very young, or has widespread disease.
• Scabies or CLM that fails two compliant courses of first-line therapy.
• Tungiasis with complicated (infected, deformed, digital) lesions.
• Lice in the eyelashes of a young child (possible safeguarding).
• Suspected sporotrichosis or any lesion that does not fit, before starting antifungals.
• Travel-related undifferentiated creeping eruption with systemic symptoms.

• CLM: secondary bacterial infection (impetigo, folliculitis, cellulitis), bullous CLM, post-inflammatory pigmentation, persistent pruritus, urticarial or eczematous reaction, and recurrence from dormant larvae. Rarely, migration into deeper tissue is reported, but the larvae generally cannot advance beyond the epidermis.^[4]
• Scabies: secondary bacterial infection (especially Staphylococcus aureus and streptococci), impetigo, post-streptococcal glomerulonephritis, rheumatic fever risk from streptococcal superinfection, localised or generalised eczema, hyperpigmentation, and crusted scabies with extreme infectivity and mortality in the frail.
• Lice: anaemia with very heavy infestation (body lice in extreme poverty), secondary infection, pyoderma, and, for body lice only, transmission of rickettsial, borrelial and trench-fever organisms.
• Tungiasis: pain, difficulty walking, secondary bacterial infection, abscess, loss of nails or digits in severe cases, and tetanus risk.
• Sporotrichosis: dissemination in immunocompromised patients and chronic skin and lymphatic disease if untreated.

In CLM the natural history is self-limiting; the larvae die within 5 to 6 weeks, and treatment shortens symptoms and usually resolves the eruption within days to weeks, although reactivation of dormant larvae can produce new tracks weeks after the first course. Treatment failure should prompt a review of compliance and a possible re-course, and even then the condition ultimately resolves because the larvae cannot complete their life cycle in humans.

Scabies and pediculosis carry an excellent prognosis if contacts are treated at the same time and compliance is good; most patients are cured after 1 or 2 applications or doses. Crusted scabies carries a higher risk of secondary sepsis and death in frail patients. Tungiasis resolves after removal of the flea, with recovery of the skin over days to weeks. Sporotrichosis usually resolves after 3 to 6 months of oral antifungal treatment.^[7]

There is no formal screening programme for CLM, scabies, lice or tungiasis in the general population, although scabies is a notifiable problem in many institutional outbreak protocols. Prevention is the practical core of all four:

• CLM: deworm dogs and cats, clean up animal faeces from public beaches and sandpits, and encourage footwear and barrier towels; returning travellers should wash off sand and shower promptly after beach exposure and report itchy creeping tracks early.^[4]
• Scabies and lice: treat household and close contacts simultaneously, wash bedding and clothing, and inspect children when scabies or lice appear in a classroom; institutional protocols should include early recognition, isolation of cases, and simultaneous treatment of contacts.^[2][3]
• Tungiasis: wear shoes, treat and maintain floors, and in endemic areas reduce the reservoir by controlling stray dogs and rats.

Patient handout points useful at the end of a consultation:

• Itch after scabies treatment can last several weeks and does not mean the treatment failed.

• Treat everyone in the household at the same time, even those without symptoms.

• Reapply scabicide to the hands if they are washed during the contact time; hands are the commonest missed area.

• Do not use veterinary or agricultural antiparasitics on people.

Pregnancy. Both albendazole and ivermectin are pregnancy category C and should be used only when the benefit outweighs the risk to the fetus; CLM is not life-threatening and can be treated with non-drug measures or deferred in pregnancy, with topical treatment reserved for troublesome cases.^[1] For scabies, permethrin 5% cream is widely used in pregnancy because of its topical action and poor absorption; AAD guidance lists it as approved for pregnant women.^[2] Lindane is contraindicated in pregnancy. Oral ivermectin for scabies is avoided in pregnancy because safety has not been established.^[5] Sporotrichosis in pregnancy may be treated with cryosurgery or local therapy because itraconazole is generally avoided; severe disease is an infectious disease specialist decision.

Children. CLM: systemic albendazole is contraindicated under 2 years and ivermectin is used only over 15 kg, so younger children are usually treated topically under specialist or guideline advice.^[1] Scabies: permethrin 5% from 2 months, sulfur ointment 5% to 10% for infants under 2 months, crotamiton for adults, sulfur for babies; benzyl benzoate 25% and spinosad 0.9% (from 4 years) are options.^[2] Head lice: pyrethrins from 2 years, permethrin from 2 months, benzyl alcohol, spinosad and ivermectin lotion from 6 months.^[6] Crusted scabies and widespread disease in children should be referred.

Older adults. Older adults are more prone to crusted scabies and misdiagnosis as eczema or urticaria; infestation can cover the scalp, face and hands. Topical permethrin is the usual first choice; lindane is avoided. Dementia and frailty increase the risk of failed application and of outbreaks in care homes, so supervised application and institutional protocols matter. Tungiasis in older people often presents with complications because of delayed presentation.

Immunocompromised. This is the main risk group for crusted scabies and for dissemination in sporotrichosis; HIV and HTLV-1 infection in particular change the expected presentation. Such patients should be referred early, and strongyloidiasis with larva currens should be actively excluded when there is a creeping eruption in an immunocompromised traveller.

• CLM. Diagnosis is clinical and inexpensive; albendazole and ivermectin are both widely available. If neither is accessible, the condition is self-limiting within 5 to 6 weeks and symptomatic relief, wound care, and treatment of secondary infection remain useful.
• Scabies. When permethrin is unavailable, 5% to 10% sulfur ointment compounded locally is safe, including in infants, and is cheap; the application schedule remains the same. Sealing garments and hot-water washing are low-cost measures.
• Lice. Conditioner and fine-toothed wet combing performed carefully on several consecutive days is effective and free; reserve prescriptions for failures.
• Tungiasis. Flame-sterilised instruments, a magnifier, and basic dressings are enough for simple extraction; closed footwear and sealing floors address recurrence.
• General. Written, illustrated skin-care instructions and teaching given to patients and, where possible, to community health workers improve adherence more than is expected.

• CLM is a dead-end animal hookworm infection of the outer skin: serpiginous track, intense itch, advancing 1 to 2 cm per day, acquired from contaminated sand or soil.
• Larvae usually die within 5 to 6 weeks, but dormant larvae can reactivate weeks or months later; systemic albendazole or ivermectin is the standard treatment.
• Scabies is a Sarcoptes scabiei infestation with burrows and night-time itch; treatment is permethrin 5% cream or oral ivermectin 200 mcg/kg, with all contacts treated simultaneously.
• Itching can persist for up to 6 weeks after successful scabies treatment and does not by itself mean failure.
• Crusted (Norwegian) scabies needs combined oral plus topical therapy in a repeated schedule and is a serious infection-control event.
• Head lice are treated with topical pediculicides and wet combing; body lice need treatment of the clothing and environment; pubic lice need partner treatment.
• Tungiasis is a sand-flea nodule on the foot, usually extracted aseptically, with attention to tetanus and secondary infection.
• Sporotrichosis is fungal, not parasitic, and is treated with oral itraconazole for 3 to 6 months.
• A travel and exposure history is the single most useful piece of information in a creeping skin eruption; speed of migration separates CLM from larva currens.
• Asymptomatic contacts of scabies, lice and tungiasis (where relevant) need treatment at the same time as the index case.
• Ivermectin and albendazole are pregnancy category C and avoided in pregnancy where possible; permethrin 5% and sulfur are the safer choices in infants and pregnancy.
• Low-cost measures (footwear, sealing garments, wet combing, sulfur ointment) are effective alternatives when first-line agents are unavailable.

Parasite and skin disease topics that belong with this one, to be linked as they are published: infectious diseases (strongyloidiasis and larva currens, soil-transmitted helminths), dermatology (eczema and urticaria mimics, bacterial skin infection), travel medicine (ill returned travellers, tropical dermatoses), and pharmacology (antihelminthics and scabicides).