Parasites of the Skin

Question 1

Pediculosis capitis

Answer 1

Head lice

Question 2

What is the causative agent of head lice?

Answer 2

Pediculus humanus capitis

Question 3

Pediculosis corporis

Answer 3

Body Lice

Question 4

What is the causative agent of body lice?

Answer 4

Pediculus humanus humanus

Question 5

Pediculosis pubis

Answer 5

Pubic lice (crabs)

Question 6

What is the causative agent of pubic lice?

Answer 6

pthirius pubis

Question 7

What is the causative agent of scabies?

Answer 7

Sarcoptes scabiei var hominis

Question 8

Infestation of the scalp by the head louse, which feeds on the scalp
and neck and deposits its eggs on the hair

Age of onset 3-11 years (but can affect all ages)

Girls > boys

Transmitted by shared hats, caps, brushes, combs, head to head
contact

Parasites size of sesame seed, 1-2mm

Answer 8

Head lice

Question 9

What are some treatment options for head lice?

Answer 9

Permethrin

Malathione (Ovide)

Lindane 1% shampoo

Ivermectin 0.8% lotion or shampoo or 200 ug/kg, repeat in 10 days

Home remedy: mayonnaise in place of cream (suffocates the lice)

Question 10

What are some preventative measures for spreading head lice?

Answer 10

Avoid contact with possibly contaminated items

Vacuum all areas

Wash and dry affected items

Soak combs in rubbing alcohol or Lysol 2% solution for 1 hour

Question 11

Infestation of the body by the louse

Larger than the head louse; 2-4mm

Feeds on the body and irritates the skin

Lives in seams of clothing

Can survive without blood meal for up to 3 days

Grabs body hairs to feed

Answer 11

Body Lice

Question 12

What are some risk factors for body lice?

Answer 12

Poor socioeconomic conditions
When clothing is not changed or washed frequently
Poverty
War
Natural disasters
Indigence
Homelessness
Refugee camp populations

Question 13

What are some differential diagnoses to consider when evaluating for head lice?

Answer 13

Seborrheic dermatitis

Question 14

What are some differential diagnoses to consider when evaluating for body lice?

Answer 14

Scabies
Bedbugs

Question 15

What is the treatment for body lice?

Answer 15

Pyrethrins/pyrethroids for 8-24 hours (Not for infants < 6 months)

Malathion

Bedding and clothing must be systematically decontaminated

Basic sanitation measures

Question 16

AKA “crabs”

Louse size 0.8 to 1.2mm

Infestation of the hair-bearing regions

Most commonly the pubic area, but can be other areas

Mild to moderate pruritis, popular urticaria, and excoriations

Most common in young adults

More extensive infestation in males

Answer 16

Pubic Lice

Question 17

How is pubic lice transmitted?

Answer 17

Sexual: Close physical contact; Sharing bed

Non-sexual: Occurs in homeless persons who have pubic lice in hair on head and back; Possibly exchange of towels

Question 18

Below are the skin findings of which infestation?

Lice appear as 1-2mm brownish-grey specks in hairy areas involved

Nits attached to hair appear as tiny white-grey specks

Can be few to numerous

Eggs at hair-skin junctions indicate active infestation

Answer 18

Pubic lice

Question 19

Below are the skin symptoms of which infestation?

Often asymptomatic

Mild to moderate pruritis for months

Excoriations and secondary infections

Patient may notice “hair nodules”

Papular urticaria

Can infect eyelashes

Answer 19

Pubic Lice

Question 20

What is the treatment for pubic lice?

Answer 20

Treatment includes patient and partner

Screen for other STDs as well

Decontaminate clothing

Medications – same as for head louse

Question 21

Parasitic infection below the skin surface

Typically spares the head and neck

Tunnels/burrows into epidermis (typically linear burrows)

Typically active at night (tunneling/burrowing), lays eggs during the day

Transmission through skin to skin contact, fomites

Answer 21

Scabies

Question 22

How is scabies diagnosed?

Answer 22

H&P

Skin scapings - Place a drop of mineral oil over a burrow, scraped off with a number 15 scalpel blade and placed under a microscope slide

Question 23

Burrows: Gray or skin colored ridges, 0.5-1cm in length either linear or wavy/zigzag pattern, with minute vesicle or papule at the end of tunnel

Really likes the webs of fingers - If have lesions/bumps in the webs of fingers, think scabies until proven otherwise

Pruritis: Intense, worse at night, may persist after infection resolves

Rash: None to erythroderma, Spares the head and neck (can be in the faces on infants however)

Crusted - In immunocompromised patients

Answer 23

Scabies

Question 24

What are the treatment options for scabies?

Answer 24

Permethrin (Elimite 5%) cream
Lindane 1% lotion or cream
Ivermectin pill

Triamcinolone 0.1% cream can resolve the dermatitis