Scabies

Question 1

What causes scabies?

Answer 1

Scabies is caused by the mite Sarcoptes scabiei and is spread by prolonged skin contact.

Question 2

Who is typically affected by scabies?

Answer 2

Scabies typically affects children and young adults.

Question 3

How does the scabies mite affect the skin?

Answer 3

The scabies mite burrows into the skin, laying its eggs in the stratum corneum.

Question 4

What causes the intense pruritus associated with scabies?

Answer 4

The intense pruritus is due to a delayed-type IV hypersensitivity reaction to mites/eggs which occurs about 30 days after the initial infection.

Question 5

What are common features of scabies?

Answer 5

Common features include widespread pruritus and linear burrows on the side of fingers, interdigital webs, and flexor aspects of the wrist.

Question 6

In which areas may scabies affect infants?

Answer 6

In infants, the face and scalp may also be affected.

Question 7

What secondary features can be seen due to scratching?

Answer 7

Secondary features include excoriation and infection.

Question 8

What is the first-line treatment for scabies?

Answer 8

Permethrin 5% is the first-line treatment.

Question 9

What is the second-line treatment for scabies?

Answer 9

Malathion 0.5% is the second-line treatment.

Question 10

How long can pruritus persist after treatment?

Answer 10

Pruritus can persist for up to 4-6 weeks post eradication.

Question 11

What should patients avoid until treatment is complete?

Answer 11

Patients should avoid close physical contact with others until treatment is complete.

Question 12

What should be done for all household and close physical contacts?

Answer 12

All household and close physical contacts should be treated at the same time, even if asymptomatic.

Question 13

What should be done with clothing and bedding on the first day of treatment?

Answer 13

Launder, iron or tumble dry clothing, bedding, towels, etc., on the first day of treatment to kill off mites.

Question 14

What does the BNF advise regarding the application of insecticide?

Answer 14

The BNF advises to apply the insecticide to all areas, including the face and scalp.

Question 15

What are the instructions for applying insecticide?

Answer 15

Apply the insecticide cream or liquid to cool, dry skin, paying close attention to areas between fingers and toes, under nails, armpit area, and skin creases.

Question 16

How long should permethrin and malathion be left on the skin?

Answer 16

Leave permethrin on for 8-12 hours and malathion for 24 hours before washing off.

Question 17

What should be done if the insecticide is removed during treatment?

Answer 17

Reapply if insecticide is removed during the treatment period, e.g., if washing hands or changing a nappy.

Question 18

When should treatment be repeated?

Answer 18

Repeat treatment 7 days later.

Question 19

What is crusted (Norwegian) scabies?

Answer 19

Crusted scabies is seen in patients with suppressed immunity, especially HIV.

Question 20

What is the treatment of choice for crusted scabies?

Answer 20

Ivermectin is the treatment of choice for crusted scabies.

Question 21

What is essential for patients with crusted scabies?

Answer 21

Isolation is essential for patients with crusted scabies.

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