A16. Scabies, pediculosis
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
- Permethrin 5% lotion
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.