[7] Scabies Flashcards Preview

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Flashcards in [7] Scabies Deck (34)
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1
Q

What is scabies?

A

An itchy rash caused by the parasitic mite Sarcoptes scabiei

2
Q

How do scabies mites colonise the skin?

A

They mate on the skin surface, the male dies and the female tunnels into the epidermis and deposits eggs along the burrow

3
Q

How long does it take for scabies mite eggs to develop from eggs to adult mites?

A

10-15 days

4
Q

What happens once scabies mites develop into adults?

A

They return to the surface and mate again

5
Q

What is the life-span of scabies mites?

A

4-6 weeks

6
Q

How are scabies mites classically transmitted?

A

Via direct skin contact

7
Q

How can crusted scabies be transmitted?

A

Via bedding, towels, clothes and furniture

8
Q

What causes the symptoms of scabies?

A

Allergic reaction to the host’s body to mite proteins

9
Q

What are the risk factors for scabies?

A
  • Overcrowding
  • Poverty and poor nutritional status
  • Homelessness
  • Poor hygiene
  • Dementia
  • Sexual contact
  • Immunosuppression
10
Q

What is the first period of scabies infection?

A

Asymptomatic infection

11
Q

After what period do scabies symptoms develop in primary infection?

A

3-4 weeks

12
Q

What are the characteristic features of scabies?

A
  • Intense itching

- Superficial burrows

13
Q

When is the itching due to scabies worst?

A

At night and when the person is warm

14
Q

How do the burrows of scabies mites often appear?

A

As linear lesions with rows of erythematous papular or vesicular lesions

15
Q

What additional skin lesions can be seen in scabies?

A
  • Widespread, symmetrical, itchy, papular eruptions around axillae, peri-areolar, abdomen, buttocks and thighs
  • Excoriation marks
16
Q

What is crusted scabies also known as?

A

Norwegian scabies

17
Q

What is crusted scabies?

A

A hyper-infestation of mites which presents as exfoliating scales

18
Q

Who is most at risk of crusted scabies?

A
  • Elderly
  • Immunocompromised
  • Decreased peripheral sensation
19
Q

How does crusted scabies appear?

A

Hyperkeratotic lesions affecting the hands, feet, nails, scalp and ear

20
Q

What secondary symptoms may be associated with crusted scabies?

A
  • Lymphadenopathy
  • Eosinophilia
  • Secondarily infected lesions
21
Q

Why is crusted scabies more concerning than classical scabies?

A
  • Very contagious

- More difficult to eradicate

22
Q

How is scabies diagnosed?

A

Clinically

23
Q

What additional techniques may help identify scabies?

A
  • Magnifying lens of burrows

- Ink burrow test

24
Q

How can diagnosis of scabies be confirmed?

A

Take skin scraping form the affected areas

25
Q

What are the differentials for scabies?

A
  • Seborrhoeic dermatitis
  • Dermatitis herpetiformis
  • Pediculosis
  • Atopic dermatitis
26
Q

What is the primary method of scabies treatment?

A

Topical application of parasiticidal preparation overnight on the whole body (including between fingers, toes and under nails)

27
Q

When should parasiticidal preparation be re-applied for scabies?

A

A week after first application

28
Q

What is the first-line parasiticidal preparation for scabies?

A

Permethrin 5% dermal cream

29
Q

How does permethrin treatment differ for crusted scabies?

A

May require 2 or 3 applications on consecutive days to penetrate hyperkeratotic areas

30
Q

What further steps should be taken to eradicate scabies?

A

Wash towels, clothes and bed-linen

31
Q

Who else should be treated for scabies in addition to the index patient?

A
  • Household members
  • Close contacts
  • Sexual contacts
32
Q

When should contacts of the index patient be treated for scabies?

A

Simultaneously to reduce risk of re-infestation

33
Q

When should treatment failure for scabies be assumed?

A

If symptoms persist beyond 6 weeks from first applications

34
Q

What are the potential complications of scabies?

A
  • Flaring or reactivation of eczema or psoriasis
  • Secondary bacterial infection
  • Social stigma and psychological harm