Scabies Flashcards
What is the name of the mites that cause scabies?
Sarcoptes scabiei
Fill in the gap: it can take up to _ weeks for any symptoms or rash to appear after the initial infestation
8 weeks
Give 2 clinical presentations associated with scabies:
1) incredibly itchy small red spots between finger webs (can be on body too)
2) track marks where mites have burrowed
What is another name for Norwegian scabies?
crusted scabies
What is Norwegian/ crusted scabies?
a serious, highly contagious infestation of scabies in immunocompromised patients who are covered in over a million mites
How does Norwegian/ crusted scabies present?
patches of red skin with scaly plaques (often like psoriasis)
How long is the life cycle of scabies?
4-6 weeks
How long does it take for eggs to develop into adults?
10-15 days
How many eggs does an average female lay?
25
How is classical scabies transmitted?
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.
How long can the mites live away from their host?
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.
How is crusted scabies transmitted?
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.
How long can the mites live away from their host in crusted scabies?
up to 7 days
What are 4 risk factors for scabies?
- Close contact with infected person
- High levels of poverty and social deprivation
- Crowded living conditions and institutionalisation
- Winter months
Name 3 complications associated with scabies.
- Secondary bacterial infection
- Secondary eczematisation
- Nodular scabies
What does a mite burrow look like?
a thin, brown-grey line of 0.2-1cm in length
What is the ink burrow test?
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.
What is involve in the skin scrapping investigation?
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.
Name 3 differential diagnosis.
- Dermatitis
- public lice
- Insect bite
What topical medication is used to treat scabies?
permethrin cream
Describe how permethrin cream should be used to treat scabies
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
Give 2 ways the household should respond to a scabies case:
1) hot wash all clothing, bedding and towels
2) all household members and close contracts need to treat themselves with permethrin cream
Give 2 medications that can be used to relieve the itching in scabies:
1) Crotamiton cream
2) chlorphenamine