Contagious, Pruritic

           Parasitic dermatosis

           Extremely common in poor and under privileged.


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.


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 


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


>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.


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. 


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.



       Secondary bacterial infection  àpyoderma

       Secondary eczematization or Lichenification



AGN (Acute Glomerulo-nephritis)

(Nephritis strain : Group- A, Beta-hemolytic Streptococci – 49, 55, 57, 60)


(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 


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


3.PCR ( polymerase chain reaction

Management of Scabies:


p Reassurance and educate the patient about  the disease

# All members should be treated

pAll clothing should be washed in boiling water



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


Topical mild steroid and antibiotics

To reduce itching and infection (Fusidic acid + Hydrocortisone cream)


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


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.


(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.