Scabies
Diagnosis and management

Definitive diagnosis requires microscopic identification of the mites, eggs, larvae or faeces. Clinical diagnosis is made by observing typical lesions on wrists, finger web spaces, axillae, penis or thighs or on eliciting the classic pattern of pruritus (at night, after a hot shower/bath). If associated with exposure to an infected person, the index of suspicion should be high even in the context of non-specific symptoms.

Immunosuppressed patients may present with Norwegian scabies. Large numbers of mites are present. The condition may not be pruritic. Extensive crusting may be seen.

Standard therapy

permethrin 5% cream topical from neck down washed off after at least 8 hours, but not more than 24 hours (ADEC B2)

Permethrin should be applied to clean and cool skin. The patient should not take a hot bath or shower prior to treatment. 1% creams and lotions are ineffective against scabies.

Pay particular attention to the areas between the fingers and toes, under fingernails and toenails, wrists, armpits, genitals, buttocks and perianal area. It is usually helpful for a second person to assist with the application of cream to areas that are not easily accessible. 

Reapply cream to the hands if they are washed within 8 hours of treatment.

Oral antihistamines can be used to control itching. 

Immunosuppressed and HIV positive patients 

These patients may prove resistant to topical therapy. Referral to a Dermatology or Infectious Diseases specialist may be necessary for treatment with systemic ivermectin. Norwegian scabies may also need ivermectin treatment.

The following points should be discussed:

• The nature of the infection 

• The need for concurrent treatment of sex partners and household contacts 

• Non-sexual transmission of scabies is possible, but requires direct and prolonged body contact.

• Clothing and bed linen which may have been contaminated by the patient within the past 2 days should be machine washed and dried (hot cycle) or dry cleaned.

•   Pruritus may persist for several weeks after adequate therapy. systemic antipruritics or topical steroids may be required for alleviation of symptoms

• Additional weekly treatments are warranted only if live mites can be demonstrated.

• Provide literature on scabies. Stress need for concurrent treatment of sex