SCABIES

Question 1

(1) A contagious parasitic infection of the skin caused by the mite Sarcoptes scabiei, var. hominis
(2) An obligate human parasite
(a) Whitish-brown, eight-legged mite.
(b) After mating, female mites burrow into the epidermis, a process facilitated by secretion of proteolytic enzymes that cause keratinocyte damage.
(c) Female mites continue to extend the burrow and lay two to three eggs per day before dying after four to six weeks.
(d) Larvae hatch in three to four days and molt three times within the burrow to reach adulthood.
(3) Primarily transmitted by prolonged human-to-human direct skin contact

Answer 1

Scabies

Question 2

Presentation

Answer 2

(1) Scabies rash appears 2-6 weeks after exposure.
(2) Intense pruritus that worsens at night is a cardinal feature.
(3) A burrow is the classic lesion; a linear, curved or S-shaped slightly elevated vesicle or papule up to 1-2 mm wide.
(a) Finger webs, wrists, sides of the hands and feet, the penis, buttocks and scrotum.Burrows may obscured by scratching and secondary lesions
(b) Partners will also be symptomatic.
1) Persistent itching after adequate treatment is due to prolonged allergic response.
2) Eczema and Impetigo may appear as secondary lesions

Question 3

Differential Diagnosis

Answer 3

(1) Insect bites
(2) Impetigo
(3) Folliculitis

Question 4

Labs/Studies/Imaging

Answer 4

(1) Ink test: Rub a black felt-tip marker across an affected area. Remove excess ink is wiped away with an alcohol pad, burrow appears darker than the surrounding skin because of ink accumulation in the burrow

Question 5

Disposition

Answer 5

Full Duty, take consideration for laundering clothing, bedding and those in close quarters with other persons.

Question 6

Complications

Answer 6

(1) Secondary infections

(2) Recurrence

Question 7

Treatment

Answer 7

(1) Treatment is two fold:
(a) Killing scabies mites & removing infestation
(b) Controlling the dermatitis & pruritus
(2) Permethrin 5% or Lindane 1% applied to entire skin surface from the neck down, including under the fingernails and toenails an in the umbilicus.
(3) After 12 hours patient will bathe.
(4) Treatment regimen should be repeated in 1 week.
(5) Topical steroids may be used to control pruritus and inflammation after treatment with a scabicide.
(6) All clothes and bedding must be washed in hot water or put in a hot dryer at the time of application.
(7) Can also be set aside wrapped in plastic bags for 14 days