ScabiesScabiesSitti Rahmah UmniyatiSitti Rahmah Umniyati

Learning objectiveLearning objective

Explain the etiology, life cycle, Explain the etiology, life cycle, pathogenesis, signs and symptoms. pathogenesis, signs and symptoms. diagnosis, prognosis, treatment, diagnosis, prognosis, treatment, epidemiology and control of scabies.epidemiology and control of scabies.

Scabies is a skin disease Scabies is a skin disease caused by a mite called caused by a mite called Sarcoptes scabiei.Sarcoptes scabiei.

It affects people of all ages.It affects people of all ages. It is usually associated with It is usually associated with

crowded living conditions, crowded living conditions, and its outbreaks often and its outbreaks often accompany wars, accompany wars, famine and famine and human migrationhuman migration

Sarcoptes scabiei Sarcoptes scabiei (itch mites)(itch mites)

Phylum: ArthropodaPhylum: Arthropoda Class: ArachnidaClass: Arachnida Order: AcarinaOrder: Acarina Family: SarcoptidaeFamily: Sarcoptidae Genus: SarcGenus: Sarcooptesptes Species: Species: Sarcoptes scabieiSarcoptes scabiei

MorphologyMorphology Capitulum and body Capitulum and body

saclikesaclike Legs 4 pairs, short (2 Legs 4 pairs, short (2

forward and 2 backward)forward and 2 backward) The anterior legs The anterior legs

terminate in delicate terminate in delicate sucking pads (pulvilli)sucking pads (pulvilli)

The posterior legs both The posterior legs both end in longhair bristle in end in longhair bristle in the femalethe female

While in the male the While in the male the third pair has bristles and third pair has bristles and the fourth pair pulvillithe fourth pair pulvilli

Sarcoptes scabieiSarcoptes scabiei Sixe of the bodySixe of the body++ 0.34 mm (female) 0.34 mm (female)++ 0.20 mm (male) 0.20 mm (male)

PathogenesisPathogenesis

Infection begin when fertile female mites are Infection begin when fertile female mites are transfered from infected individuals by direct transfered from infected individuals by direct contactcontact

Female, usually at night , burrows into the skin, Female, usually at night , burrows into the skin, progressing at the rate of about 2-3 mm per progressing at the rate of about 2-3 mm per day. day.

The burrow is confined to the corneous layer of The burrow is confined to the corneous layer of the skinthe skin

Lesions appear as short, sinous, or slightly Lesions appear as short, sinous, or slightly raised , cutaneous burrowsraised , cutaneous burrows

Thread-like lesions or vesicles may be seen on Thread-like lesions or vesicles may be seen on the skinthe skin

With primary infection, itching and With primary infection, itching and skin eruption are usually delayed for skin eruption are usually delayed for several weeks. several weeks.

As sensitization develops, the typical As sensitization develops, the typical scabies rash appears on various part scabies rash appears on various part of the body that do not necessarily of the body that do not necessarily correspond to the location of active correspond to the location of active adult female mites but represent a adult female mites but represent a generalized response to the generalized response to the allergen.allergen.

Minute vesicular swelling , possibly Minute vesicular swelling , possibly produce by the irritating fecal produce by the irritating fecal deposits or excretionsdeposits or excretions

The intense itching , aggragated by The intense itching , aggragated by warmth and precipitation , cawarmth and precipitation , cauuses ses scratching, which spreads the scratching, which spreads the infestation, irinfestation, iriitates the lesions, and tates the lesions, and induces secondary bacterial infection.induces secondary bacterial infection.

As a result multiple papular vesicular, As a result multiple papular vesicular, and pustular lesions may be produced. and pustular lesions may be produced.

At first clinical manifestation may be At first clinical manifestation may be mild, but after some weeks the skins mild, but after some weeks the skins becomes sensitized , resulting in an becomes sensitized , resulting in an itching erythematous eruption.itching erythematous eruption.

Life CycleLife Cycle

3 daysForm

a lateral branch

First nymph

2nd nymphFemale

male

Burrows Into the skin2to3 mm at night

The male excavates lateral pockets The male excavates lateral pockets in the burrowsin the burrows

The female during her life span 0f 4-The female during her life span 0f 4-5 weeks deposits up to40-50 eggs, 5 weeks deposits up to40-50 eggs, 2-4 at a time, in the burrow.2-4 at a time, in the burrow.

The female may suThe female may surrvive off the vive off the host for 2-3 days at room host for 2-3 days at room temperature.temperature.

Clinical featuresClinical features

The main symptom is intensive itchiness which The main symptom is intensive itchiness which is more severe at night. is more severe at night.

The common affected areas are finger webs and The common affected areas are finger webs and the skin folds of wrists, armpits, buttocks, groins, the skin folds of wrists, armpits, buttocks, groins, elbows, nipples and lower abdomen. elbows, nipples and lower abdomen.

The face and scalp are usually not affected, The face and scalp are usually not affected, except in small infants. Thread-like lesions or except in small infants. Thread-like lesions or vesicles may be seen on the skinvesicles may be seen on the skin

A patient who was infested with A patient who was infested with scabiesscabies

shows the typical pruritic shows the typical pruritic red papules in the red papules in the interdigital spaces of interdigital spaces of handhand

shows the typical pruritic shows the typical pruritic red papules in the fingerred papules in the finger

A nursing home patient who was A nursing home patient who was infested with scabiesinfested with scabies

shows the typical pruritic shows the typical pruritic red papules in the axilla. red papules in the axilla.

these papules on the these papules on the flexural wrist are flexural wrist are secondary to scabies secondary to scabies infestation.infestation.

Scabies rash on the Scabies rash on the hands. Burrows are hands. Burrows are visible. visible.

Scabies burrows Scabies burrows between the fingersbetween the fingers

Scabies with flexural Scabies with flexural wrist involvementwrist involvement

Scabies with inflamed Scabies with inflamed lesions in periumbilical lesions in periumbilical distributiondistribution

Mode of transmissionMode of transmission

Scabies usually spreads through Scabies usually spreads through direct contact with an infected person. direct contact with an infected person.

Clothing and bedding may also carry Clothing and bedding may also carry the mite and transmit the disease.the mite and transmit the disease.

Incubation periodIncubation period

For people without previous For people without previous exposure of the disease, incubation exposure of the disease, incubation period is around two to six weeks. period is around two to six weeks.

People who have been previously People who have been previously infested may develop symptoms infested may develop symptoms earlier, usually within 1-4 days after earlier, usually within 1-4 days after re-exposure. re-exposure.

DiagnosisDiagnosis

Diagnosis can be confirmed by Diagnosis can be confirmed by demonstration of the mites, eggs, demonstration of the mites, eggs, or scybala (fecal pellets). or scybala (fecal pellets). Because the mites are located Because the mites are located under the surface of the skin, under the surface of the skin, scrapings must be made from the scrapings must be made from the infected area. infected area.

Skin Scraping TechniqueSkin Scraping Technique

1.1.Place a drop of mineral oil on a sterile Place a drop of mineral oil on a sterile scalpel blade. (Mineral oil is preferred scalpel blade. (Mineral oil is preferred over potassium hydroxide solution or over potassium hydroxide solution or water. Mites will adhere to the oil, skin water. Mites will adhere to the oil, skin scales will mix with mineral oil, refractility scales will mix with mineral oil, refractility of differences will be greater between mite of differences will be greater between mite and oil, and oil will not dissolve fecal and oil, and oil will not dissolve fecal pellets.) pellets.)

2.2.Allow some of oil to flow onto the papule. Allow some of oil to flow onto the papule. 3.3.Scrape vigorously six or seven times to Scrape vigorously six or seven times to

remove the top of the papule. (There remove the top of the papule. (There should be tiny flecks of blood in the oil).should be tiny flecks of blood in the oil).

4. 4. Transfer the oil and scraped material to a Transfer the oil and scraped material to a glass slide (can use an applicator stick).glass slide (can use an applicator stick).

5.5. Add 1 or 2 extra drops of mineral oil to the Add 1 or 2 extra drops of mineral oil to the slide, and stir the mixture. Any large clumps slide, and stir the mixture. Any large clumps can be crushed to expose hidden mites. can be crushed to expose hidden mites.

6.6. Place a coverslip on the slide and examine Place a coverslip on the slide and examine (first on low power). The adult mites range (first on low power). The adult mites range from approximately 215 to 390 microns in from approximately 215 to 390 microns in length, depending on sex. The eggs are length, depending on sex. The eggs are 170 microns long by 92 microns wide, and 170 microns long by 92 microns wide, and the fecal pellets are about 30 by 15 the fecal pellets are about 30 by 15 microns. The fecal pellets will be yellow-microns. The fecal pellets will be yellow-brown. brown.

Plastic Box or Petri Dish Method Plastic Box or Petri Dish Method

If mineral oil preparations of skin scrapings If mineral oil preparations of skin scrapings fail to demonstrate the mites, the encrusted fail to demonstrate the mites, the encrusted skin scrapings, etc., can be placed in a small skin scrapings, etc., can be placed in a small plastic box or small petri dish.plastic box or small petri dish.

The container should be left undisturbed at The container should be left undisturbed at room temperature for 12 to 24 h. Away from room temperature for 12 to 24 h. Away from the living host, the mites will drop down onto the living host, the mites will drop down onto the bottom of the box or dish and can be seen the bottom of the box or dish and can be seen with a magnifying glass or with a dissecting with a magnifying glass or with a dissecting microscope. microscope.

This demonstrates the application of mineral oil to This demonstrates the application of mineral oil to suspected scabies lesions prior to scraping.suspected scabies lesions prior to scraping.

The scale and mineral oil The scale and mineral oil are applied to a slide after are applied to a slide after scraping the skin looking for scraping the skin looking for scabies mites.scabies mites.

The scraping is viewed The scraping is viewed under the microscope at low under the microscope at low magnification. The scabies magnification. The scabies mite measures about 0.1 to mite measures about 0.1 to 0.3 mm in diameter, and is 0.3 mm in diameter, and is not visible with the naked not visible with the naked eye, but very slight eye, but very slight magnification will make it magnification will make it visible.visible.

Differential diagnosisDifferential diagnosis

ImpetigoImpetigo ScabiesScabies

Scarlet FeverScarlet Fever ScabiesScabies

PrognosisPrognosis

Prognosis is good with persistence Prognosis is good with persistence treatmenttreatment

TreatmentTreatment Infestation with the itch mites can be Infestation with the itch mites can be

eradicated by the use of 1% gamma benzene eradicated by the use of 1% gamma benzene hexachloride in a lotion BASE. hexachloride in a lotion BASE.

The medication should be applied in the The medication should be applied in the evening after the lesions have been cleaned evening after the lesions have been cleaned and soften by soaking in a warm water and and soften by soaking in a warm water and should be left of overnight. should be left of overnight.

One or two additional application, at weekly One or two additional application, at weekly intervals may be necessary to kill those mites intervals may be necessary to kill those mites that hatch subsequent to the initial treatment.that hatch subsequent to the initial treatment.

For pediatric use, 10 per cent concentration , For pediatric use, 10 per cent concentration , N-ethyl-o crotonotoluide (Eurax) in a cream or N-ethyl-o crotonotoluide (Eurax) in a cream or lotion base, is prefered by many physicians. It lotion base, is prefered by many physicians. It is applied to the skin of whole body from the is applied to the skin of whole body from the chin downs and a second application is made chin downs and a second application is made after 24 hoursafter 24 hours

A cleansing bath is given after another 24 A cleansing bath is given after another 24 hours. hours.

Allergic reactions and local irritation have been Allergic reactions and local irritation have been reported.reported.

Treatment of choice for scabies is to apply Treatment of choice for scabies is to apply permethrin (Elimite) overnight from the neck permethrin (Elimite) overnight from the neck down, and to ensure that everyone in the down, and to ensure that everyone in the patient's family is treated at the same timepatient's family is treated at the same time

EpidemiologyEpidemiology

Scabies is transmitted by personal Scabies is transmitted by personal contact especially by person sleeping contact especially by person sleeping together, less frequently by towels, together, less frequently by towels, clothing and bed linens. clothing and bed linens.

InInffectivity is low and the indication ectivity is low and the indication tends to run a limited course in healthy tends to run a limited course in healthy persons of cleanly habitspersons of cleanly habits

ControlControl

Prevention of scabies requires the Prevention of scabies requires the treatment of infected individuals, the treatment of infected individuals, the sterilizations of garments and sterilizations of garments and bedding, and personal cleanlinessbedding, and personal cleanliness