scabies and pediculosis

8/12/2019 Scabies and Pediculosis

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SCABIES AND

PEDICULOSIS

Dr. Akreti Sobti

Dept of Dermatology, Venereology & LeprosyK. J. Somaiya Hospital


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Scabies Common ectoparasitic skin infection Causative miteSarcoptes scabiei

Characterized by itchy papular lesions and

burrows (tunnels housing mites)

Primarily affects children and young adults

Predisposing factors are poverty, overcrowding

and poor hygiene.


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Morphology of mite

Ovoid bodydorsoventrally flattened

Female longer than male

Dorsal surfacebristles and spines

Four pairs of short legs, anterior two pairs have

small suckers.

Larva has three pairs of legs.


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Adult female mite


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Biology of the mite

Ovigerous female

Larva

1st nymph

Adult male 2ndnymph

Moulting pocket


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Clinical features

Nocturnal itching

Positive family history

Rash

burrows/tunnels

Papules

nodules

excoriations


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Sites of predilection

Finger web spaces

Wrist

Axillae

Breast

Umbilicus

Genitals


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Diagnosis

Demonstration of the mite under the microscope

Burrow ink test

Liquid tetracycline test

Complications:

Secondary bacterial infection

Eczematization


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Clinical variants

Scabies in the clean

Crusted/Norwegian/hyperkeratotic scabies

Nodular scabies

Infantile scabies

Genital scabies

Scabies incognito

Ping pong scabies

Animal scabies


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Nodular scabies


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Genital scabies


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Ping pong scabies


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Crusted/Norwegian scabies

The patient harbours millions of mites.

Host response to the mite is modified, allowingthem to multiply.

Etiology:Reduced itch : Sensory neuropathy, spinal injury

Reduced scratching : Immobility due to paralysisor arthropathy

Altered immunity

Mental retardation


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Norwegian Scabies

Clinical features:

Large warty crusts on extensor surfaces.

Diffuse erythema and scaling

Generalised lymphadenopathy

Nail involvement

* Rx same as for classical scabies

Keratolytics for crusts


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Treatment

Topical agents:

Gammabenzene hexachloride1%

Benzyl benzoate25%

Permethrin5%

Sulphur-5%

Crotamiton- 10%

Oral : Ivermectin


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Pediculosis

Ectoparasitic infestation caused by the lice:

Pediculus capitisPediculosis capitis

Pediculus corporisPediculosis corporis

Phthirus pubisPediculosis pubis


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Pediculosis capitis

Common in children & women

No correlation between the hair length & louse

infection rates

Spread of lice is encouraged by poverty, poorhygiene & overcrowding

Transmission by direct head to head contact


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Clinical features

Scalp pruritus

Secondary bacterial infection:

Impetigo

Matting of hair[plica polonica]

Occipital lymphadenopathy

Generalised rash

Fever

O/E : Adult lice and Nits in the scalp


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Pediculosis corporis

(Vagabonds disease) Mostly seen in adult males

Poor hygiene, poverty and overcrowding

Infrequently washed clothes harbour body lice

Lice rarely seen on body


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Clinical features

Severe itching on trunk esp. back

Erythematous macules and papules

Excoriations

Hyperpigmentation in chronic cases

Examination of clothing seams reveals lice and

nits


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Pediculosis pubis

Sexually transmitted condition

Affected young adults

nocturnal itching

Sites : pubis, inner thighs,

perineum

O/E :

Lice and nits in the pubic hair

Excoriations and bluish macules on

lower trunk


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Complications

Secondary bacterial infection

Louse borne relapsing feverBody louse

Epidemic typhusBody louse

Trench feverBody louse


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Treatment

Type Main therapy Supportivetherapy

Capitis GBH 1%

Permethrin2%

Malathion0.5%

Antibacterials

Antihistaminics

Shampooing

Corporis Wash clothesin boilingwater

Hot ironing

Good hygeineAntihistaminics


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scabies and pediculosis

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