Rash: Scabies Flashcards
What is scabies?
A highly infectious rash caused by the parasitic mite Sarcoptes scabiei.
How is scabies spread?
Direct skin to skin contact or via fomites (less common).
Cause of scabies?
An infestation of the skin by mite Sarcoptes scabiei resulting in a pruritic eruption
Appearance of rash in scabies?
Small, erythematous papule with haemorrhagic crusts on fingers, elbows, axillary folds, thighs, genitalia, feet.
What causes the rash in scabies?
From a local allergic reaction to the presence of the scabies mite, rather than being directly caused by the mite itself.
What are some key risk factors for scabies?
Living conditions: poverty and overcrowding are key risk factors.
This includes institutional care facilities, such as residential aged care homes, hospitals, and prisons.
Clinical features of scabies?
1) Intense, widespread pruritus
2) Linear burrows on the side of fingers, interdigital webs and flexor aspects of the wrist (face and scalp may be affected in infants)
3) 2ary features: excoriation, infection
1st line for management of scabies?
Permethrin 5%
2nd line for management of scabies?
Malathio 0.5%
How long can pruritus persist in scabies post eradication?
Up to 4-6 weeks
What causes the intense pruritus associated with scabies?
A delayed-type IV hypersensitivity reaction to mites/eggs which occurs about 30 days after the initial infection.
How does the BNF advise to apply the inseticide in scabies?
ALL areas, including the face and scalp.
Pay close attention to areas between fingers and toes, under nails, armpit area, creases of the skin such as at the wrist and elbow.
When should treatment be repeated in scabies?
7 days after
Where are scabies ‘burrows’ typically found?
These are small irregular tracks ~1cm in length, classically found in the webbed spaces between the fingers
What is crusted scabies?
A severe variant of scabies where an individual is infected with thousands or millions of mites (compared with 5-20 in a typical infection).
What is a key complication of scabies?
2ary bacterial infection of scabies rash (due to itching).
Which bacteria typically causes 2ary infection in scabies?
GAS (S.pyogenes) or S.aureus
What is measles caused by?
An infectious disease caused by a morbillivirus of the paramyxovirus family.
Appearance of measles rash?
Maculopapular rash lasts 6-8 days
What associated symptoms can there be in measles?
- prodrome: fever, coryza, cough, non-purulent conjunctivitis
- Koplik spots
How is measles spread?
Droplets
Incubation period of measles?
10-14 days
How long are you infective for with measles?
infective from prodrome until 4 days after rash starts
What are Koplik spots?
White spots (‘grain of salt’) on buccal mucosa.
These appear BEFORE the rash in measles.
Where does the measles rash typically start?
Behind the ears (and then spreads to the whole body)
Prevention of measles?
MMR vaccine at 18 months
Key investigation of measles?
IgM antibodies can be detected within a few days of rash onset
Managment of measles?
1) Notifiable disease –> inform public health
2) Mainly supportive
Who should admission be considered in in measles?
Immunosuppressed or pregnant women.
Management of a child who is not immunised against measles that comes into contact with measles?
Offer MMR vaccine (within 72 hours)
Why can the MMR vaccine be offered if a non immunised child comes into contact with measles?
As vaccine-induced measles antibody develops more rapidly than that following natural infection
What is the most common complication of measles?
Otitis media
What is the most common cause of death in measles?
Pneumonia
What are some complications of measles?
- Otitis media
- Pneumonia
- Encephalitis
- Subacute sclerosing panencephalitis
- Diarrhoea
- Myocarditis