Scabies, Dermatology

MEDICINE-DERMATOLOGY-DISEASES BY ARTHROPODS SCABIES LIFECYCLE HISTORY

1.

Reported for >2500

years

2.

Aristotle

3.

Celsus recommended sulphur mixed

1.

Eggs incubate and hatch (3-4 days)

2.

90% of the hatched eggs die and 1%

described Lice in the flesh

survive 3.

Larva (3 pairs of legs) migrate to the

with liquid as remedy

skin surface  Burrow into the intact

4.

Bonomo related mite to the disease

Stratum Corneum  Short Burrows

5.

First

(Molting Pouches) (3-4 days)

human disease known to be

caused by a specific pathogen

4.

Larger Nymph

5.

Adults

6.

Mating

 A. INTRO: a.

Skin infestation caused by arthropod Sarcoptes scabiei var hominis

b. B.

OF SARCOPTES SCABIEI:

7.

Highly pruritic and contagious skin lesions

takes place once

a.

Female fertile for life

b.

Male

die

Female secrete proteolytic enzyme 

Dissolve stratum corneum further  Serpentine burrows with Laying of eggs

INCIDENCE:

 further burrowing (1-2 months)

a.

300 million cases annually

b.

One

8.

Transmission of impregnated female

of the 6 major epidermal parasitic skin

diseases (EPSD)

c.

Any

d.

M:F::1:1

age group

OTHER VARIETIES OF SARCOPTES SCABIEI (Mange) 1.

C.

ETIOPATHOGENESIS: a.

Risk Factors: i. Young age

Infest dogs, cats, pigs, ferrets and horses

2.

Unable to reproduce in humans

3.

Cause irritation and transient dermatitis

ii. Illiteracy iii. Poor socioeconomic condition iv. Poor housing condition v.

Overcrowding

d.

Mode of transmission:

vi. Poor hygiene, irregular bathing

i. Direct skin to skin contact (common)

vii. Sharing of clothes and towels

ii. Sexual contact

viii. Homosexual Men

iii. Indirect fomites (Larger the no of the arthropod, more the chances)

b.  Agent: i.

Sarcoptes scab iei var hominis

SARCOPTES SCABIEI VAR HOMINIS 1.

Female

a.

infests the human

Can be seen with naked eyes

2.

Male

is half the size of female

3.

4 pairs of legs

4.

Unable to fly or jump

5.

Crawl at the rate of 2.5 cm/min

6.

Cannot penetrate deeper the outer

D. CLINICAL: a.

History: i.

Age:

ii. Sex: any iii. Socioeco:any iv.

Itching 1.

Short time or persistent (7 year itch)

2.

More at night

layer of epidermis 7.

Complete life cycle in human

8.

Survive in the beddings and clothes for 2-3 days at room temp

c.9.

<20 deg C  remain immobile

SASHMI-5 TH BATCH

any

a.

Sensation more in quiet env

b.

Steroid levels are low at night

3.

Peak At 2- 3 weeks

4.

Immunocompromised Immunocompromised might not have itching

v. Infestation in family members

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MEDICINE-DERMATOLOGY-DISEASES BY ARTHROPODS

b.

Examination: i. Primary lesions: 1.

E.

Sites (Circle of Hebra):

VARIANTS: a.

Infantile:

a.

Head and face (in children)

i.

b.

Webbed spaces of fingers

ii. Vesicopustules with eczematisation eczematisation

c.

Flexor area of wrist

d.

Axilla

e.

Antecubital area

f.

Breast and nipples (in female)

g.

Abdomen

h.

Umbilicus

i.

Genital areas (Glans penis, shaft and

i.

scortum involvement in males is

ii. >=0.5 cm

typical)

iii. Due to hypersensitivity reaction to the mite

Gluteal folds (Involvement of back in

iv. In the covered areas ( Axillary folds and

 j.

iii.

2.

3.

Because sebum secre is less in infants in head and face  So no lysis of the org

iv. H/O scabies in parents

b.

Nod ular: Firm, red itchy nodules

scotum)

Feet

Lesions: a.

Burrows

b.

Papules

c.

Pustules

d.

Nodules

e.

Utricarial papules and plaques

c.

a.

Pathognomic of Scab ies infestat ion

b.

Short (2-3 mm) and thin (width of a

Cr usted/ Norwegian: i.

Thick hyperkeratotic crusted lesions with scales

ii. Usually immunocompromised, elderly and retarded persons iii. Hundreds to millions mites

Burrows:

iv. IgG and IgE are high v. CD8 predominanc pr edominance e

d.

human hair) c.

May involve head and face 1.

old age) k.

Rare

Straight or tortuous (serpentine)

Scabies incognito: i.

Modified by steroids

raised tract d.

In the superficial epidermis

e.

With a vesicle at the tip (where the

e.  Atypical/ Clean Scabies: i.

Itching with few scattered papules

mite enters the burrow) 4.

Mite

 f.

may be visible as a small dot

Scabies galeusus: i.

ii. Secondary lesions

Development of primary lesions of syphilis in scabetic lesions of genetalia

1.

Utricaria

2.

Impetigo

3.

Eczematous plaques

a.

Insect bites

4.

Pyoderma (Aerobic, anaerobic or mixed)

b.

Atopic dermatitis

c.

Contact dermatitis

d.

Psoriasis

e.

Utricaria

SASHMI-5 TH BATCH

F.

D/D:

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MEDICINE-DERMATOLOGY-DISEASES BY ARTHROPODS necessary (Some dev larva survive the initial RX)

b.

1% Lindane i. C/I in pediatrics

G. INVESTIGATIONS: a.

ii. Transcutaneous absorption 

Diagnostic test: i.

Neurotoxicity 2.

Identification of the mites, eggs, eggshell fragments and mite pellets

Oral: a.

(Scybala)

repeat after 10-14 days

ii. Drop of mineral oil over the burrow 

IVERMECTIN:

Longitudinal and lateral scrapping of  skin with scalpel blade  Study under

1.

Not FDA recommended for the RX

2.

MOA:

microscope iii.

Avoid

Failure

Binds selectively to glutamate

gated chloride channel of nerve and

using KOH as it can dissolve the

muscle cells  Paralysis and cell death

pellets iv.

Ivermectin, 0.2 mg/kg once; can

of the identification of eggs or

3.

t1/2=16 hr, metabolized in the liver

4.

C/I in infants

mites does not rule out the diagnosis

b.

Localizing the burrow: i.

Application of topical

Scabies in Pregnancy and lactat ing mother:

tetracycline tetracycline

Washing off the excess  study under

1.

6% Sulphur Cream

2.

Ivermectin, Petmithrin and Lindane C/I

the Wood Lamp  Fluorescence ii.

Application of the washable ink

ii.  Antihistaminics: c.

Others:

1.

i. Dermatoscopy

To relief itching  Hydroxyzine Hydroxyzine hydrochloride

ii. PCR

iii.  Antibiotics:

iii.  IgE and eosinophilia iv. Skin biopsy

H. TREATMENT: a. General:

I.

For sec bac infections

COMPLICATIONS: a.

Impetigo

i. Consultation with the dermatologist

b.

Furunculosis

ii.

Treatment of the family members and the

c.

Cellulitis

people in close contact

d.

Pyelonephritis

e.

Post strep glomerulonephritis glomerulonephritis

f.

Abscess

g.

Sepsis

h.

Death

iii. Providing reassurance that the disease is not a reflection of poor hygiene

b.

1.

Specific: i. Scabicide: 1.

Topical: a.

5% Permethrin cream i.

DOC, esp for >2m and small children

ii. Dose: Application all over the body, except on the scalp; Shower after 8-14 hours; repeat the application after 7 days if 

SASHMI-5 TH BATCH

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