SCABIES
ONE OF THE MOST COMMON SKIN DISEASES IN BANGLADESH
Contagious, Pruritic
Parasitic dermatosis
Extremely common in poor and under privileged.
CAUSATIVE AGENT
Sarcoptes scabiei (microscopic (0.3-0.5 mm long), eight-legged, burrowing itch mite).
Notoedres cati (animal scabies)
F Infestation occurs in the stratum corneum of the skin.
F Once away from the human body
mites usually do not survive more than 72 hours.
F When living on a person, an adult female mite can live up to a month.
F Male mite dies after copulation. Female mite dies after egg laying.
F An affected individual harbours about 10-15 mites.
INCIDENCE
Worldwide distribution.
Both sex, all races.
But common in poor hygienic condition, low socioeconomic classes. Children, hypersensitive & immunosuppresed persons are more prone to have scabies.
Seasonal influence : More in winter. Reservoir of infection: Patient.
Period of communicability: Until cured
Mode of transmission:
Skin to skin contact- 97%
House hold utensils-3%
Incubation period:
Primi exposure-2-4 weeks.
Re-exposure-1-4 days.
MODE OF TRANSMISSION
(i) By direct, prolonged, skin-to-skin contact with a person already infested with scabies. Examples: Madrashas, hospitals, garments’ factories, prisons, hostels, prolonged hand shack or hug, sexual partners & household members etc.
(ii) Sharing contaminated clothings, beddings, towels etc.
(iii) Poor hygiene (slums, brothels etc)
EMBED PowerPoint.Slide.8
PRESENTATION OF SCABIES:
Various presentations may develop in scabies patients
>Generalized pruritus without any skin lesions
>Generalized pruritus with various form of skin lesions → Papules, pustules, papilovesicular bullons, nodular, crusted, exorited, ulceration with oozing , secondary eczematization and urticaria
>Presence of burrow à slightly elevated, grayish, tortuous lines in the skin
(Pathognomic)
>Pruritus is more at night and during day time the pruritus is tolerable but persistent
>Other members of the family may be affected – since it is contagious
> may be presented with complications ~ like AGN, Pyoderma, secondary eczematization etc.
USUAL SITES OF PREDILECTION
Though almost anywhere in the skin may be involved, it is most often found:
finger webs, wrists, elbows (antecubital fossae), axillae, breasts , around umbilicus, genital area, buttocks—
An imaginary circle intersecting axillae, elbow flexures, wrists hands & crotch called the circle of Hebra.( Classical scabies )
(usually face & scalp spared except in immunocompromised patients)
In children, common sites of infestation include the: Scalp, Face, Neck, Palms of the hands. Soles of the feet.
How soon after infestation will symptoms begin?
For a person who has never been infested with scabies, symptoms may take 4-6 weeks to begin. For a person who has had scabies before, symptoms appear within several days.
COURSE & PROGNOSIS
The prognosis for complete recovery from scabies infestation is excellent. In patients with weak immune systems, the biggest danger is that the areas of skin involved with scabies will become secondarily infected with bacteria.
COMPLICATIONS:
Early
Secondary bacterial infection àpyoderma
Secondary eczematization or Lichenification
Urticaria
Late
AGN (Acute Glomerulo-nephritis)
(Nephritis strain : Group- A, Beta-hemolytic Streptococci – 49, 55, 57, 60)
Erythroderma
(By Norwegian scabies)
Remember notes
Sensitization begins about 2 to 4 weeks after onset of infection.
The fertilized female mite burrows into stratum corneum and deposit her eggs
The female mite can survive only 2 or 3 days away from warm skin
Burrows can be made visible by Indian ink and gentian violet applied to the infected areas followed by removed with alcohol / spirit Êthin thread like burrow retains the ink
Lab Diagnosis
INVESTIGATIONS
Diagnosis is usually based on history & clinical features.
Consider the diagnosis of scabies in any patient presenting with a recent onset of intense night itching that increases at night. Any patient with itching for which cause can not be found should receive a therapeutic trial for scabies.
1. By using Indian ink Microscopic examination to demonstrate the mite
¹ A burrow is sought and position of mite is determined
Hands, wrist (commonly mites found)- also elbow, genitalia, buttock, axilla etc
Place a drop of mineral oil over lesion (A vesicle or pustule containing mite may be noted at the end of the burrow
Gently scraping with surgical blade / needle with the epidermis A Place on glass slide and add normal saline and cover up with cover slip
A Microscopic examination of scabies mites
2.Dermoscopy
3.PCR ( polymerase chain reaction
Management of Scabies:
GENERAL MEASURES
p Reassurance and educate the patient about the disease
# All members should be treated
pAll clothing should be washed in boiling water
TOPICAL MEASURES
Specific
F Permethrin( 5% cream ) once apply whole body (except scalp and face) followed by bathing in the next morning and repeat after one week
FCrotamiton cream(10%) 5 nights application whole body
FMonosulfiram 25% alcoholic solution. Dilute with water (same proportion) 3 nights application
F6-10% precipitated sulphur – 3 nights application whole body
F25% Benzyl Benzoate emulsion- 12 hourly application for 3 consecutive days
Supportive
Topical mild steroid and antibiotics
To reduce itching and infection (Fusidic acid + Hydrocortisone cream)
SYSTEMIC MEASURES
Specific Supportive
Tab. Ivermectin (3 mg / 6 mg ) Antihistamine
200mg /kg single dose Tab. Citirizine
(10 mg) 0+ 0+1 for 1 months
Treatment of complications if any
Secondary bacterial infection (Pyoderma)-
Antibiotics – Flucloxacilin / Cephradin / Azithromycin
AGN – Consultation with Nephrologists
Follow up – to prevent relapse
PREVENTION
Good hygiene is essential in the prevention of scabies. When a member of a household is diagnosed with scabies, all that person’s recently worn clothing and bedding should be washed in very hot water.
DIFFERENTIAL DIAGNOSIS
(i) Atopic dermatitis.
(ii) Papular urticaria
(iii) Pyoderma
(iv) Prurigo simplex
Pediculosis corporis
Insect bite
Lichen Plannus
Gianotti-crosti syndrome
Other medical causes of generalized pruritus.
