Scabies

Question 1

What is the name of the mites that cause scabies?

Answer 1

Sarcoptes scabiei

Question 2

Fill in the gap: it can take up to _ weeks for any symptoms or rash to appear after the initial infestation

Answer 2

8 weeks

Question 3

Give 2 clinical presentations associated with scabies:

Answer 3

1) incredibly itchy small red spots between finger webs (can be on body too)
2) track marks where mites have burrowed

Question 4

What is another name for Norwegian scabies?

Answer 4

crusted scabies

Question 5

What is Norwegian/ crusted scabies?

Answer 5

a serious, highly contagious infestation of scabies in immunocompromised patients who are covered in over a million mites

Question 6

How does Norwegian/ crusted scabies present?

Answer 6

patches of red skin with scaly plaques (often like psoriasis)

Question 7

How long is the life cycle of scabies?

Answer 7

4-6 weeks

Question 8

How long does it take for eggs to develop into adults?

Answer 8

10-15 days

Question 9

How many eggs does an average female lay?

Answer 9

25

Question 10

How is classical scabies transmitted?

Answer 10

Classical scabies is transmitted through close/prolonged skin contact with an infected person.

Scabies is frequently sexually acquired.
Transmission through casual contact, such as a handshake, is unlikely.

Question 11

How long can the mites live away from their host?

Answer 11

The mites can live away from a host for an average of 24–36 hours, although survival can be prolonged at lower ambient temperature and higher humidity. Transmission via shared clothing or bedding can therefore occur.

Question 12

How is crusted scabies transmitted?

Answer 12

Crusted scabies is highly contagious, and, in addition to transmission by direct contact, is easily transmissible via bedding, towels, clothes, and upholstery due to the large numbers of mites on an infested person.

Question 13

How long can the mites live away from their host in crusted scabies?

Answer 13

up to 7 days

Question 14

What are 4 risk factors for scabies?

Answer 14

1. Close contact with infected person
2. High levels of poverty and social deprivation
3. Crowded living conditions and institutionalisation
4. Winter months

Question 15

Name 3 complications associated with scabies.

Answer 15

1. Secondary bacterial infection
2. Secondary eczematisation
3. Nodular scabies

Question 16

What does a mite burrow look like?

Answer 16

a thin, brown-grey line of 0.2-1cm in length

Question 17

What is the ink burrow test?

Answer 17

Back or blue ink is applied to the suspected papule and then wiped off with alcohol to remove surface ink. If the person has scabies, a dark zigzagged line running across and away from the lesion appears, due to ink tracking down the mite burrow.

Question 18

What is involve in the skin scrapping investigation?

Answer 18

Papules or linear lesions are scraped with a number 15 scalpel blade which has been dipped in liquid paraffin. Multiple (four or more) lesions should be scraped from each patient, with scraping sufficient to cause bleeding.
The skin scrapings are then transferred to a slide and viewed under a microscope.
The presence of mites, eggs, or mite faecal material confirms the diagnosis.
This test is 100% specific if a mite is seen, however, sensitivity is generally less than 50% due to the low number of mites typically found on an infested person.

Question 19

Name 3 differential diagnosis.

Answer 19

1. Dermatitis
2. public lice
3. Insect bite

Question 20

What topical medication is used to treat scabies?

Answer 20

permethrin cream

Question 21

Describe how permethrin cream should be used to treat scabies

Answer 21

1) apply to whole body onto cool skin (not after shower/bath)
2) leave for 8-12 hours before washing off
3) repeat a week later to kill the eggs that survived and have now hatched

Question 22

Give 2 ways the household should respond to a scabies case:

Answer 22

1) hot wash all clothing, bedding and towels
2) all household members and close contracts need to treat themselves with permethrin cream

Question 23

Give 2 medications that can be used to relieve the itching in scabies:

Answer 23

1) Crotamiton cream
2) chlorphenamine