Is It a Recurrent or Resistant Scabies? Dr Chieng Chae Hee

Consultant Paediatrician

Sibu Hospital

8 April 2017

Scabies

• A common condition in children

• “seven-year itch”

• Not properly treated or inadequately treated

Pathogen

• Sarcoptes scabiei var hominis • A whitish-brown eight-legged mite • It has no eyes (Kudis Buta!) • Size - <0.5mm

Life Cycle

• On human body, scabies mites can live up to 2 months

• Mating once but fertile for the rest of the life

• Females lay 2-3 eggs per day

• Continue to lay eggs for 1-2 months

One life cycle takes 10-17 days

Transmission

• Human to human by direct contact with infected lesions

• Through contaminated clothing or linens

• Mites can survive off a host for 24 to 36 hours

• Animal to human transmission can occur but symptoms are transient

Incubation Period

• 3-6 weeks after primary infestation

• Patients with previous infestation, symptoms usually begin within 3 days after re-infestation

Clinical features

• Itchy rashes is a prominent feature

• Worst at night

• The pruritus is due to type-IV hypersensitivity to the mite, mite feces, and mite eggs

Rashes distribution

Head is spared except in very young children

Papular rashes with hemorrhagic crusts

Vesicular/bullous rashes

Nodular scabies

Crusted (Norwegian) scabies

Infected scabies

Case 1

• 4 yr old boy

• Admitted for acute gastroenteritis

Case 2

• 1 yr 2 mth old boy

• Admitted for viral wheeze

• Was treated as scabies in Nov 2016 • Whole family treated with crotamiton but applied cream over the rashes only

• Clothing washed with detergent

• Rashes recurred 3 months later • Both parents and other 3 siblings have similar rashes

• Itchiness was worst at night

Diagnosis

• Clinical

• Skin scraping

• Dermatoscopy

• Digital photography

Treatment

• Education • Eradicate the mites

• Medications • Permethrim 5% lotion • Benzyl benzoate 12.5% and 25% emulsion • Crotamiton 10% cream • Sulphur 6% in petroleum • Lindane (GBHC 1%) lotion • Oral ivermectin (for Norwegian scabies)

• Clothing and bedding

• Wash in hot water (≥50⁰C for 10 minutes) • Dry cleaning • Store in a sealed plastic bag for three days (72 hours)

Treatment in specific considerations Treatment in specific considerations

8

Clinical condition Recommended therapy Alternative therapy Additional measures Comments

Classical scabies i. Infants < 2

months

Sulphur 6% in petroleum in ointment base for 3 days

Treat whole body including the face (avoid eyes and mouth)

Treat all family members/close contacts simultaneously

ii. Children < 2 years

Two applications of Permethrin 5% for 8-12 hours at one week apart

Sulphur 6% in petroleum for 3 days

Treat whole body including the face (avoid eyes and mouth)

Crotamiton cream TDS for 5-7days for nodular scabies

iii. Children < 12 years

Two applications of permethrin 5% for 8-12 hours at one week apart

Benzyl Benzoate 12.5% Whole body neck and below for 3 consecutive days

Crotamiton cream TDS for 7-14 days for nodular scabies

iv. Adults Two applications of permethrin 5% for 8-12 hours at one week apart

Benzyl Benzoate 25% whole body; neck and below for 3 consecutive days

People in close physical contact, even without symptoms, should receive treatment at the same time

v. Pregnancy/ lactating women

Two applications of permethrin 5% for 8-12 hours at one week apart

-

Crusted scabies Permethrin and

Ivermectin for

Scabies

Oral ivermectin alone or in combination with permethrin is very useful OR Several applications of Benzyl Benzoate

Apply keratolytic agents (salicylic acid ointment) to hyperkeratotic areas.

Keep nails short and apply medication to subungual areas.

Patients may need admission.

Strict control to prevent spread of infection

Interventions for Treating Scabies Strong M, Johnstone P

Cochrane Database Syst Rev. 2010

• OBJECTIVES • To evaluate topical and systemic drugs for treating scabies.

• MAIN RESULTS

• Twenty-two small trials involving 2676 people were included. One trial was placebo controlled, 18 compared two or more drug treatments, three compared treatment regimens, and one compared different drug vehicles.

• Fewer treatment failures occurred by day seven with oral ivermectin compared with placebo in one small trial (55 participants). Topical permethrin appeared more effective than oral ivermectin (140 participants, 2 trials), topical crotamiton (194 participants, 2 trials), and topical lindane (753 participants, 5 trials). Permethrin also appeared more effective in reducing itch persistence than either crotamiton (94 participants, 1 trial) or lindane (490 participants, 2 trials). No difference was detected between permethrin (a synthetic pyrethroid) and a natural pyrethrin-based topical treatment (40 participants, 1 trial), and between permethrin and benzyl benzoate (53 participants, 1 trial), however both these trials were small.

• No significant difference was detected in the number of treatment failures between crotamiton and lindane (100 participants, 1 trial), lindane and sulfur (68 participants, 1 trial), benzyl benzoate and sulfur (158 participants, 1 trial), and benzyl benzoate and natural synergized pyrethrins (240 participants, 1 trial); all were topical treatments. No trials of malathion were identified.

Treatment –cont..

• Stop the transmission • Treat everyone in the household and close contacts SIMULTANEOUSLY

• Patient can only back to school 24 hours after the start of treatment

• Notify health side for any outbreak in boarding school/long house

• Stop the itchiness • Oral antihistamine =/- topical corticosteroid to control pruritus which may

last for 3 weeks post treatment

• Treat superimposed bacterial skin infection

• Involve pharmacist to advise on the method of application, duration, etc

Follow up

• One month after treatment

• Treatment failure • Reappearance of papules/vesicles/burrows

• Itchiness does not improved/improved but worsened

• Causes: • Inadequate or improper treatment

• Re-infestation

• Management of treatment failure • Re-educate and re-counsel patient and family members

• Re-treat with topical scabicides using an alternative agent

Take Home Message

• Almost all recurrent scabies are due to inadequate eradication of mites rather than resistant.

• Provide written information on method of application of topical medication

• Treat every close contact, and also the bedding and clothing!

Work together to eradicate scabies!

Website: www.moh.gov.my –Guideline for management of scabies in adults and children