PADJADJARAN UNIVERSITY

MEDICAL SCHOOL

TROPICAL MEDICINE BLOCKCASE 9 : SCABIES

TUTOR GUIDE

Block title: Tropical Medicine

Case title: Scabies

Case theme: The purpose of this week is to review the sign and symptoms,

aetiology, epidemiology, pathophysiology, laboratory findings,

diagnosis, complication, management prevention and control, and

medico-ethico-legal aspect of scabies.

Case objective for the student:

By the end of the week the students will be able to describe the:

1. Sign and symptoms of scabies.

2. Etiology.

3. Epidemilogy.

4. Pathogenesis.

5. Laboratory findings.

6. Diagnosis.

7. Complication

8. Management.

9. Prevention and control of scabies.

10. Ethico-medico-legal aspect of scabies.

CASE TITLE: SCABIES

CASE SYNOPSIS

TUTORIAL CASE : SCABIES

Budi 15 year-old boy , present to the Dermato-Venereogical out patient clinic with

pruritic lesions affecting the whole body surface. He feels very itchy especially at

night.. Skin lesions distribute generally mainly on the finger webs, wrist, axillary

folds and his scrotum. The lesions consist of many pruritic papular lesions with mild

erytematous papules and crusts. On direct microscopic examination from skin

scrapings revealed mite. His mother and his younger brother also have the same skin

disease. The patient was diagnosed as scabies based on history, physical

examination and laboratory findings. After the patient treated with permethrin 5%

cream once a week for two weeks, the patient was free from symptomps.

Reference for the students and tutors.

1. Odom R.B, James W.D, Berger T.G. Andrews’ Diseases of the Skin.

Clinical Dermatology, W.B Saunders Company; Philadelphia, 2000: 563-

567.

2. PARASIT

Tutorial 1 Page 1

Identify the problems

- Pruritic papular lesion especially at night

- Distribution of the lesion

- The member of the family have the same diseases

- Overcrowded

Problem 1: Pruritic papular lesions.

Guiding question for tutor to focus on skin lesions

What is the definition of pruritic papular lesions? (please refer to

neurobehaviour system) :

- Pruritic means itch, especially at night because the mite more active in

low humidity and warm.

- Papule : are circumscribed, solid elevations with no visible fluid,

varying in size from a pinhead to 1 cm, they maybe acuminate,

rounded conical, flat topped, or umbilicated and may appear white, red,

yellow etc.

What are the possible causing of pruritic papular lesions ?

- Itching begins with sensitization of the host. In reinfections, itching

begin immediately and the reaction maybe clinically more intense.

Problem 2: Distribution of the lesion

You are a medical student at the fourth year in Dermato-venereological out patient

clinic. You meet a 15 year-old patient, name Budi who complain about itching

especially at night for about one month.. His brother and mother have the same

symptomps . He stayed with another 8 persons in a small house (6x6 m). On

physical examination revealed pruritic papular lesions located on his finger webs,

wrist, axillary folds and scrotum.

Guiding question for tutor:

What kind of diseases which have the same lesions and its distributions?

- Scabies with the distribution of lesions are finger webs, wrist,

antecubital fosae, axillae, areolae, and areas around the umbilicus, the

lower abdomen, genitals and buttocks. And this distributions called the

circle of Hebra.

- The lesions of pediculosis corporis and pediculosis pubis can mimics

scabies however the distribution of pediculosis corporis mainly on the

inter scapular area and for pediculosis pubis on the genitals area.

What’s your Hypothesis? - Scabies, Pediculosis corporis , pediculosis pubis

Tutorial 1 Page 2

- What is the diagnosis of this patient ?

- Explain the pathogenesis of the disease !

- What is the complication ?

What is the diagnosis of this patient?

- The cardinal signs for scabies: 1.the presence of fierce itching at night (what

is?). 2. The distributions of the diseases are: finger webs, wrist, axillary folds

and scrotum. 3. Another member of friend or family is also affected. The

eruption is characteristic in boy; itchy papules on the scrotum and penis are

typically. 4. Microscopic examination under lower magnification demonstrate

mite, egg, larva, nympha and or scibala of the mite

Explain the pathogenesis of the disease!

- Sarcoptes scabiei is the causative organism, usually contracted by close

personal contact, such as nursing an infested patience, over crowding or

sleeping together, and in frequently by the common use of contaminated

towels, bed linen and clothing. The female mite is 0,3 to 0,5 mm long the

fertilized female burrows into the stratum corneum and there deposits her

Dermatological examination: Beside pruritic papular lesions and erythematous-

papules lesions, you find many canaliculies on Budi's interdigital areas of his hands.

Skin scraping from this area you find an oval and ventrally flattened mite with 0,4

mm long and some eggs.

eggs. A view after start of the burrows, egg laying begins. The male dies after

copulation, the female dies after laying the eggs. The eggs hatch into larvae in

3 to 4 days. The larvae are transformed into nymphs and these in turn into

adults. During this time the parasites maybe on the skin and ay burrow into it

without causing pruritus or discomfort. Sensitization begins about 2 to 4

weeks after onset of infection. Severe itching begins sensitization of the host.

In reinfection itching begins immediately and the reaction maybe clinically

more intense.

-

What’s the canaliculi ?

The characteristic lesions barely discernible to the naked eye. These are slightly

elevated, grayish, straight or tortuous lines in the skin. A vesicle or pustule maybe

produced at the end of the burrow, especially in infants and children. The burrow or

canaliculi which are produces female mites, occur mainly on the palms, the palmar

and lateral aspects of the finger. The mite is situated at the vesicle near the blind end

of the burrow. In addition, a papular pruritic eruption is present, ussualy without

recognizable burrow. In histologic examination of the specimen containing a burrow

refills that the burrow in almost its entire length is located within the horney layer.

Only the extreme, blind and of the burrow, when the female mite is situated, extends

in to the stratum malphigi.

What are the complications ?

- The complications are: secondary infection and eczematization.

Tutorial 2 Page 1

Guiding question:

Is the treatment appropriate?

- Permethrin 5% is the safest as well as the most effective medication for

scabies. Permethrin is a synthetic piretroid that is lethal to mites and has

extremely low toxicity for humans.

Permethrin is thoroughly rubbed to the skin from the neck to the feet with

particular attention given to the creases perianal areas and the free nail edge

and folds. It is washed off 8 to 10 hours later.

Budi is treated by cream permethrin 5% for 10 hours once in a week, repeated one

week later. The patient advised to control next 2 weeks.

- The other treatment for scabies are lindane, 6% to 10% precipitated sulphur in

petrolatum.

Tutorial 2 Page 2

Guiding question:

1. Why is the itching still present?

2. How is to prevent this disease?

Tutor guide

1. Why is the itching still present?

- The itching is still present because of the hypersensitization reaction.

2. How to prevent this disease?

- Everybody who contact with the patient should be treated.

- Health education especially personal hygiene.

Tutorial 1 Page 1

EPILOGUE

After 2 weeks Budi comes and completely cured.

After 3 weeks Budi visited Dermato-Venereological clinic and feels the itching

subside. No new lesions were found. No more medication was given.

You are a medical student at the fourth year in Dermato-venereological out patient

clinic. You meet a 15 year-old patient, name Budi who complain about itching

especially at night for about one month.. His brother and mother have the same

symptomps . He stayed with another 8 persons in a small house (6x6 m). On

physical examination revealed pruritic papular lesions located on his finger webs,

wrist, axillary folds and scrotum.

Tutorial 1 Page 2

Dermatological examination: Beside pruritic papular lesions and erythematous-

papules lesions, you find many canaliculies on Budi's interdigital areas of his hands.

Skin scraping from this area you find an oval and ventrally flattened mite with 0,4

mm long and some eggs.

Tutorial 2 Page 1

Guiding question:Budi is treated by cream permethrin 5% for 10 hours once in a week, repeated one

week later. The patient advised to control next 2 weeks.

Tutorial 2 Page 2

After 3 weeks Budi visited Dermato-Venereological clinic and feels the itching

subside. No new lesions were found. No more medication was given.

EPILOGUE

After 2 weeks Budi comes and completely cured.