Scabies

Sarcoptes scabiei var hominis
- Obligate human parasite
Transmission by direct physical contact or contact with infected clothes
Highly contagious
Incubation period 3 – 6 weeks
Risk factors
- Nursing homes
- Childcare facilities
- Prisons
Pathomechanism
- Female mites burrow into stratum corneum, lays eggs and feces
- Feces and dead mites trigger type IV hypersensitivity
Clinical features
- Intense pruritus, especially at night
- Skin lesions
  - Elongated erythematous papules
  - 2 – 10 mm burrows (elevations in the skin)
  - Vesicles
  - Excoriation due to itching
- Predilection sites – warm areas with thin skin
  - Wrists
  - Fingers
  - Male genitalia
Diagnosis
- Dermoscope
- Clinical
Treatment
- Permethrin 5% lotion
  - Applied to the whole body and left on the skin for 8 – 12 hours
  - The rest of the family should be treated too
- Lindane 1% lotion
- Oral ivermectin
- Symptomatic treatment of pruritus
  - Oral antihistamines
  - Topical steroids

Pediculosis

Lice infection
Transmission by direct physical contact or indirect contact with infected clothes, etc.
Risk factors
- Crowded places
- School
- Homeless
Pathomechanism
- Delayed allergic reaction to lice saliva
- May be asymptomatic for weeks while sensitization occurs
Pediculosis capitis
- Pediculus humanus capitis (head louse)
- Most common in children
- Clinical features
  - Scalp/neck pruritus
  - Louse eczema on back of neck
- Diagnosis
  - Detection of lice on the scalp or hair
- Treatment
  - Permethrin shampoo
  - Lindane shampoo
  - Malathion shampoo
  - Then mechanical removal with a fine-toothed comb
  - Cleaning of all hair tools, bedding, clothes, etc.
Pediculosis corporis
- Pediculus humanus corporis (body louse)
- Most common in crowded, unsanitary living conditions
- Clinical features
  - Pruritus
  - Bites on skin
  - Scratching lines
- Diagnosis
  - Detection of lice in clothing
- Treatment
  - Topical permethrin
  - Cleaning of all bedding, clothes, etc.
Pediculosis pubis
- Pthirus pubis (crab louse)
- Transmitted by sexual contact
- Most common in teenagers and young adults
- Pruritus in genital area
- Blue-purple macules in patients with chronic infection
- Diagnosis
  - Detection of lice in pubic hair
- Treatment
  - Topical permethrin
  - Cleaning of all bedding, clothes, etc.