Skin ectoparasitosis

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Human Acarian Gale


It is a cosmopolitan ectoparasitary disease, highly contagious, due to the colonization of the skin by a sarcoptes scabiei sarcoptes, variety hominis


  • Widespread worldwide affection, affects all individuals regardless of gender or ethnicity
  • Transmission:

Direct human contact: skin-to-skin, most often within a couple (Sexually Transmissible Infection) or a family

Indirect: rarely, by contact with laundry or especially bedding

  • Parasitology: mandatory human parasite, lifespan of 1 to 2 months, the female lays 3 to 5 eggs per day in the furrow of the surface layer of the epidermis. Each egg will hatch, giving a larva then a nymph and then an adult in 20 days. Adult Sarcopte survives no more than 1 to 2 days outside its host


  • Typical shape:

Incubation: 3 weeks in case of first infestation, 1-3 days if re-infestation

Subjective sign: pruritus: diffuse, sparing face and back, nocturnal upsurge, often marital or family

Objective injuries:

non-specific ▪: frequent, due to scraping

Topography: evocative, interdigital spaces, anterior face of wrists, elbows, umbilical, buttocks, inner thighs, external genitalia in men, nipple and breast areola in women

Specifics: rarer, to be systematically searched

Scabrous furrows: the path of the female mites in the corneal layer, sinuous lesions a few millimetres long, visible mainly between the fingers and on the anterior side of the wrists, can be highlighted by coloring at the anchor, each sillo n contains the eggs laid and, at one end, there is a discrete elevation corresponding to the position of the female mites

Beaded vesicles: small translucent yeasts, resting on an erythematous base, sit mostly in interdigital spaces

Scabrous nodules: papulo-nodules, purple reds, pruriginous, sometimes excoriated, sitting mainly on the axillary and genital regions of the man

  • Clinical forms:

Infant Gale: In addition to the signs already mentioned, there are vesiculo-pustules

palm and plantar nodules, peri-axillary scabinous nodules, possible facial damage

Profuse Gale: characterized by the profuse and extensive nature of the rash (including the back). It is the result of a late diagnosis, sometimes of an immune deficiency

Hyperkeratosic Gale (norwegian): highly contagious

prurit▪: often discreet or absent

Plot: Immunosuppressed or Elderly In the Community

Clinic: Full-body injury, including face, scalp and nails, with hyperkeratosic areas

Gale of "clean people": misleading (because it is pauci-lesion, very discrete specific signs), the diagnosis is based on history (characteristics of pruritus and family context) and the search for specific lesions

Complicated shapes:

Overinfection: Impétiginization of Lesions

Eczema: secondary to scabies or its treatment

Post-Scabieux Nodules: ubiquitous, pruriginous, red or copper papuloular lesions, which may persist for several weeks after effective treatment. They are of immuno-allergic origin


  • Without treatment: it persists indefinitely and becomes more complicated
  • Under treatment: the pruritus disappears, usually in a few days, sometimes it persists longer (2 to 4 weeks). Beyond this time, there is talk of post-scabrous pruritus that may be linked to re-infestation or persistence of the condition

Positive diagnosis:

Diagnosis is, above all, clinical and based on:

  • Anamnesis (nocturnally strengthened familial preuritus) and evocative topography rash
  • Parasitological examination: scratch a furrow with a vaccineostyle, collect the material of this furrow by taking. Optical microscope examination allows the adult female eggs or mites to be seen

Differential diagnosis:

Body pediculosis, animal scabies (which gives humans a pruritus with excoriated lesions, but no furrows), other causes of pruritus


  • Goals: treatment of the patient, bedding and loved ones
  • Local treatments:

Benzoate (Ascabiol®): 10% lotion

Directions: after a warm bath, on moist skin and respecting the face and mucous membranes, one applies: J1 – 2 applications in the evening at 10 minutes apart, J2, J3, J4 – – renew the application without washing, J5 – – take a bath. In infants, a single diluted brushing of 1/2, kept 12-24 h, bandage hands to avoid accidental ingestion

Side effects:

Locals: irritation, cooking, contact eczema

Generals: neurological toxicity if ingestion or skin passage

Organochlorines (Lindane: Scabecid®): 1% lotion

Instructions: a single application on dry skin, apply the product and then rinse (after 12 hours in adults, after 6 am in children). To be renewed 1 week after if failure

Side effects:

Local: contact irritation and eczema

Generals: neurological toxicity, kidney, hematological and liver toxicity

Contraindications: child under 2 years of age, pregnant woman (greater risk of skin passage)

Crotamiton (Eurax®): 10% cream

Indications: Symptomatic treatment of pruritus and scaly nodules

Application mode: 2 to 3 times a day

Others: Pyrethrine (Spregal®), Benzochloryl (DDT®), Vacuum Vaseline (2-10%, especially for infant scabies)

  • General treatment: Ivermectin (Mectizan®): 3 mg and 6 mg tablets

How to use: at a rate of 200 g/kg on an on-set for 2 hours, i.e. 1 tablet of 3 mg/15 kg, a second dose at 15 days interval set may be required

Indication: crusty scabies, scabies of HIV-infected patients

Contraindications: pregnancy, child less than 15 kg or 2 years old

  • General measures: disinfection of laundry and bedding for the 3 days prior to treatment and during treatment (leached and ironed with hot iron), those that cannot be washed are sidelined for 3 days or powdered by Aphteria® for 48 hours in a large pouch, concomitant treatment of contact subjects even without clinical signs


  • Pediculoses are ubiquitous pathologies related to infestation by cosmopolitan blood-eating insects: lice
  • Three species of lice are likely to infect humans:

Pediculus humanus variety capitis: who lives in the scalp

Pediculus humanus variety corporis: who lives in clothes and feeds on the body

Phtirius pubis (or inguinalis): who lives on the pubis

  • Parasitology: Lice are 1-3 mm insects, visible to the naked eye, the female lays an average of 10 nits (eggs) per day that hatch in 8 days to give nymphs that become adults in 10 days. The female lives for 1 to 3 months but can survive outside her host (a few hours for P. capitis and up to 3 weeks for P. corporis)

Pediculosis of the head:

  • It is due to the infestation of the scalp by the louse of the head (Pediculus humanus variety capitis)
  • Epidemiology: the most common of pediculoses, preferentially affects school-aged children (4-11 years), mostly direct human transmission (by contact) rarely indirect (by clothing or a hairbrush)
  • Clinical events:

Prurit: scalp (50% of cases), especially in temporal, occipital and retro-ear regions, which can extend to the neck and upper back

Scratching injuries: scalp and neck

Overinfected crustal lesions (impétiginization), cervical adenopathy or even eczema (any impetigo of the neck or scalp should have a pediculosis sought)

  • Diagnosis of certainty: is based on the discovery of live lice and the presence of nits (retro-ear regions)

Body pediculosis:

  • It is due to the infestation of the body by the body's lice (Pediculus humanus variety corporis)
  • Epidemiology: much rarer than scalp pediculosis, predilecated on subjects in a precarious state, direct human-to-human transmission (promiscuity of night asylums) or indirect (clothing)
  • Parasitology: the louse circulates on the body while feeding, then takes refuge in the clothes and lays its eggs
  • Clinical events:

Prurit: intense and widespread (related to awareness of lice)

Scratching lesions: scattered on the trunk and root of the limbs, which may be haemorrhagic or over-infected, sometimes urticaran or melanocodemic lesions

  • Diagnosis of certainty: the discovery of lice and nits on clothing or on the body during undressing

Pubic pediculosis (phtiriase):

  • This is an ectoparasitosis due to Phtirius inguinalis, pubic or morpion
  • Epidemiology: rare, mainly direct transmission through sexual contact (STIs).  Indirect contamination is, in theory, possible by towels or bedding
  • Parasitology: unlike the head louse and the body lice which are very mobile, the adult lives clinging to the hairs of the pubis and adjacent hairs (inguino-fessiers, thighs, abdominals, chests) and sometimes the axillary hairs, beard, eyelashes and Eyebrows
  • Clinical manifestations: pruritus (pubic, sometimes armpits, beards, eyebrows…), scratching lesions or local overinfection…
  • Diagnosis of certainty: discovery of lice and nits attached to the emergence of hairs

Treatment of pediculoses:

Treatments are neurotoxic insecticides for louse; regardless of their class, they must have a pediculicide and lenticide activity

Shampoos and powders are less effective than solutions, lotions or creams. Spray use is contraindicated if the child or parent is asthmatic due to the risk of bronchospasm

  • Pharmacological classes:

Organophosphates (Malathion: Prioderm®): is the leader, 0.5% lotion for local application, avoided before 6 months, pediculicide and lenticide, an application, stingray by stingray, of 10-20 ml on the scalp and non-wet hair, then followed, 12h apr (e) non-treat shampoo, vinegared water rinse and careful combing

Pyrethrins: the duration of the application varies according to age and the specialty used (a few minutes to a few hours), pediculicide and lenticide, there are several forms: lotion, solution, shampoo, cream. Example: lice item® shampoo (0.4%) and lotion (0.3%)

Lotion: Apply to the base of the hair to moisten the entire scalp and hair, leave in contact for 10 minutes and then rinse

Shampoo: put 8-20 ml on the previously wet scalp, lather well, leave in contact 5-10 minutes then rinse. 2nd application 24 hours later

Organochlorines (Lindane: Scabecid®, Aphteria®): pediculicide but weakly slow, should be avoided (potential neurological toxicity). Aphteria®: left overnight, renew the application the next day and 8 days after

  • Indications:

Pediculosis of the scalp:

Individual Measures: First-line: Malathion-based lotions (Prioderm®), for people living in the same household, only parasitis subjects are treated

Other measures: clothes and bedding should be treated in the event of a massive infestation: washing sheets, pillows, stuffed animals and beanies in a machine at 50oC. Combs and brushes are cheated in insecticide or isolated for 3 days

Body Pediculosis: The decontamination of laundry and bedding by Aphteria powder® is usually sufficient

Pubic pediculosis: pubic lice are treated in the same treatment as scalp pediculosis, hair shaving is sometimes necessary if nits are plentiful, clothing and bedding are washed at 50oC, detect another associated STI and treat Partners

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