Scabies

Question 1

What organism causes scabies?

Answer 1

Mite Sarcoptes scabiei

Question 2

How long do mites live away from human skin?

Answer 2

24-36h

Question 3

How long does it take for larvae to hatch?

Answer 3

2-4d

Question 4

How long does it take to mature into adult mites?

Answer 4

10-14d

Question 5

How long does it take after initial infection to develop a hypersensitivity reaction?

Answer 5

~3 weeks after first exposure

Question 6

What is the classic presentation of scabies?

Answer 6

Burrows, erythematous papules and generalized pruritus that is typically worse at night. Burrows are usually located between the fingers, in the flexure of the wrist, elbows or armpits, or on the genitals or breasts; however, they can sometimes be difficult to find

Question 7

What secondary bacterial infections are common?

Answer 7

1. Staphylococcus aureus

2. Group A streptococcus

Question 8

What complications can scabies lead to?

Answer 8

1. Stigmatization
2. Depression
3. Insomnia
4. Indirect financial costs

Question 9

What is Norwegian scabies?

Answer 9

Crusted scabies is a rare condition caused by the host response to control the mite, resulting in hyperinfestation with millions of mites, severe inflammation and hyperkeratotic reaction

Question 10

What is Norwegian scabies associated with?

Answer 10

1. HIV
2. Human T-lymphotropic virus 1
3. Leukemia
4. T cell lymphoma
5. Autoimmune disease
6. Developmental delay
7. Malnutrition

Question 11

How can you diagnose scabies?

Answer 11

1. Clinical: history of pruritic rash, worse at night, present in characteristic locations, esp. w/ similar symptoms occurring in other household members
2. Skin scraping (scraping an oil-covered scalpel blade across a burrow and examining the sample microscopically)
3. A burrow ink test (covering a lesion with ink and removing it with alcohol leaves ink tracking in the burrows)
4. Dermatoscopy (direct visualization of magnified skin). This option is not practical in many locations, especially remote communities.

Question 12

What are the recommended scabies control measures?

Answer 12

1. Treat all symptomatic and asymptomatic household members and close contacts with one of the therapies described in Table 1.
2. To prevent reinfection, treat all household members and close contacts at the same time as the known case.
3. All bed linen (sheets, pillowcases, blankets) and clothing worn next to the skin (underwear, T-shirts, socks, pants) should be laundered using a hot cycle wash and a hot drying cycle.
4. If hot water is not available, put all linen and clothing into sealed plastic bags and store them away from household members and close contacts for five to seven days. The mite cannot survive beyond four days without contact with human skin.
5. Children may return to child care or school the day after completing their initial treatment series.
6. By improving living conditions and building local expertise in Indigenous communities, individual morbidity and the risk of scabies spread can be reduced.

Question 13

What are the options for scabies management in Canada?

Answer 13

First Line 1. Kwellada-P Lotion, Nix Dermal cream (5% Permethrin cream) - leave on for 12-14h following by bathing, repeat in 7d, age restriction >3mo

Second line 2. Eurax Cream (10% crotamiton lotion/cream): apply for 24h, may be repeated in 24h, wash off 48h after last application

3. Sulphur (8-10%) precipitated in petroleum jelly: daily x 3d, no repeat, safe in pregnancy and for infants but messy
4. Benzyl benzoate 28% (adults), 10-12.5% (children): apply x 24h, repeat 1d apart, caution in pregnancy
5. Lindane 1% cream, apply 8-12h (adults), 6-8h (children) then bathe, if new mites or papules after 7d repeat, caution is small children, associated with neurotoxicity, ataxia, tremors, bone marrow suppression
6. Ivermectin 200mcg/kg PO x 1, may req. repeat in 2wk, not safe infants <15kg, pregnant, or lactating women, not licensed in Canada

Question 14

What are the CPS recommendations regarding scabies and working with Indigenous communities?

Answer 14

1. Thoroughly inform themselves concerning the signs and symptoms of scabies, current diagnostic measures and treatment options.
2. Engage in advocacy efforts to raise awareness of the link between scabies and substandard living conditions, and press for improvements to basic living standards. For more information, see the Canadian Paediatric Society position statement “Housing need in Canada: Healthy lives start at home”.
3. Help to lower infection rates through advocacy and education, because scabies should be a relatively infrequent health problem in a country such as Canada.