02-17 Infestations Flashcards

Goal: To introduce two common skin problems caused by infestations

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1
Q

This lecture has tons of pictures

A

Review them!

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2
Q

Scabies causative organism and life cycle

A

.

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3
Q

Scabies Sites of Infestation

A
  • flexor wrist
  • extensor elbow
  • between fingers, toes
  • breast
  • butt
  • genitals
  • waist
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4
Q

Dx Scabies

A

mineral oil on finger webs, scrape and look

OR

spray with ink, wait, wipe off

OR

ELISA

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5
Q

Why can’t you get folliculitis on your soles/palms?

A

No hair! (hopefully)

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6
Q

Tx scabies?

A
  1. permetherin (from crushed chrysanthemums)
  2. malathion

Treat all close personal contacts

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7
Q

Variants of lice infestation

A
  1. Head Lice - Pediculus humanus var. capitis
  2. Body Lice - Pediculus humanus var. humanus
  3. Crabs - Phthirus pubis
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8
Q

Txing lice

A
  • permetherin (RID) or malathion (OVIDE) shampoo
  • nit comb
  • bactrim - kills commensals that lice feed on for B Vitamins
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9
Q

How are body lice transmitted vs. head lice?

A

body lice are transmitted by fomites! groooooosss

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10
Q

Public Lice 101

  • Transmission
  • Pathophys
  • Physical Findings
  • Treatment
A

Transmission

  • a. transmitted by close physical or sexual contact
  • b. May be by clothing, towels, bedding
  • c. Other STD often evident.

Pathophysiology

  • a. Phthirus pubis - smallest louse
  • b. pubic hair, but also infest eyebrows, lashes, chest, beard, axilla or legs.
  • c. 1° ∆s due to pruritus and scratching.
  • d. can live 2-3 days off the host.

Physical findings

  • a. Pubic itching is 1° sx.
  • b. Excoriations, erythem. paps., or maculae cerulea (steel gray macules [SEEN HERE])
  • c. small brownish organisms on pubic hair/surrounding skin.
  • d. Nits near base of hair shaft.
  • e. Other hairy skin may be infected (e.g., eyelashes)

Treatment

  • a. Kwell or pyrethrin/piperonyl butoxide-containing shampoo (lathered in, left on for 5-10 minutes and washed out; repeat in 1 week)
  • b. All sexual contacts should be treated.
  • c. Fucking shave, good god
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11
Q

Scabies 101

  • Natural Hx
  • Pathophysiology
  • Physical Findings
  • Variations
  • LAb Findings
  • DDx
  • Tx
  • Public Health Tx
A

Natural history

  • common 2% of derm patients
  • become epidemic in war, overcrowding and low hygiene
  • Current “pandemic” in US and Canada has been going on since appx 1973.
  • Affects 300 million worldwide

Pathophysiology

  • infestation Sarcoptes scabiei variant hominis
  • close prolonged physical contact, venereally; ?fomites
  • After mating on skin female mite burrows into jct of strata corneum and granulosum.
    • (O2 by diffusion so mite can’t penetrate too far)
  • She burrows 2 mm/day, depositing ~10-25 eggs before death in 4 wks
  • Larvae emerge from eggs in 3-5 days.
  • Sensitization to mite prots is felt to be necessary before sx
    • 1st exposure: may not develop sx for 1-2 mos
    • re-exposure: sx faster
    • Th1 DTH rxn
  • COMPLICATIONS: excoriation, secondary bacterial infection, post streptococcal glomerulonephritis and acarophobia (parasitophobia).

Physical findings

    1. classic burrow: 5-10 mm curved ridges/thread-like, usually excoriated → crusted papules.
  • Common lesion locations are genital areas, flexor wrists, elbows, finger and toe webs, buttocks, breasts, waistline. Head and scalp are spared in adults.
    1. Lesions are intensely pruritic, especially at night.
    1. Eczematous changes are the primary expression of the problem.
    1. Secondary infection frequently leads to impetiginization, ecthyma, even cellulitis.

Variations

  • Nodular scabies: persistent red-brown pruritic nodules occurring especially in genital, intertriginous skin
    • (?exaggerated hypersensitivity)
  • Scabies in infants: h&n and esp hands and feet
    • Vesicles and pustules.
  • Crusted (Norwegian) scabies: tons of mites (?abnl immune resp)
    • hyperkeratotic, crusted eczematous or papulo-squamous appearing dermatitis
    • widespread: face, palms, soles, and nails
    • senile, MR, Down’s syndrome, immunosuppressed.
  • d. Scabies in the clean: only 1 - 2 mites found.

Laboratory findings

  • Scrapings: Mites, ova, feces
  • Bx: scale crust (ova, mites, feces), spongiosis, and infiltrate of lymphocytes, histocytes, eos
  • ELISA

DDx

  • Other eczematous dermatoses, esp atopic
  • Other arthropod bites, e.g., fleas
  • Pyoderma

Tx

  • ??Lindane WTF I thought he said no…
  • Crotamiton (Eurax) cream or lotion
    • also antipruritic; recommended tx for infants/kids, pregnant women
  • permethrin (Elimite), lotion (once, ~repeat in 1 wk)
  • precipitated sulfur ointment
  • benzyl benzoate malathion (Ovide) terpenoids (tea tree oil)
  • Oral ivermectin (not yet FDA approved): 200 ug/kg x2 1-2 weeks apart.

Public Health Considerations

  • tx close contacts and family members
  • Wash or store 1 wk in bag: clothes, bedding
  • In children treat head also. Pay close attention in all patients to nails, intertriginous regions, genitals
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12
Q

Head Lice 101

  • Natural Hx
  • Pathophys
  • Physical Findings
  • Tx
A

Pediculosis capitis

Natural history

  • a. Occurs most commonly in children and may appear in epidemic form in schools, day care centers, playgrounds (6-12 million cases per year)
  • b. Higher incidence in conditions of overcrowding and poor hygiene, but anyone may contract c. Uncommon in the black population
  • c. Transmitted by close contact, shared hats, hair care articles

Pathophysiology

  • a. Infestation with Pediculus humanus variant capitis
  • b. Lice favor scalp hair, especially of the occipital scalp, but may infest the beard, pubic hair.
  • c. Lice leave hairs to bite and obtain a blood meal from surrounding skin, releasing a mild toxinwhich causes purpuric spots and irritation.
  • d. Sensitization to louse products creates more inflammatory lesions, thus initial symptoms typically occur only after prior exposure. Secondary infection frequently occurs.
  • e. Nits are egg cases which are laid near the scalp surface. Eggs hatch in average of 7 days. Adult female lives approximately 1 month. Adult can live off host without a blood meal only 2-3 days; nits can live off host for 3 weeks.

Physical Findings

  • a. Pruritus is the most common symptom.
  • b. Lice are seen especially on temporal, occipital scalp.
  • c. Nits are small, oval, whitish-to-translucent, oblong objects firmly cemented to hair shaft.
  • d. Erythematous papular bites are seen in peripheral scalp and onto neck. These are often excoriated, with oozing and crust formation.
  • e. Regional adenopathy is common-secondary to pyoderma.

Treatment

  • a. Lindane lotion or shampoo (shampoo lathered in, left on 5-10 minutes, then washed out, repeated in 9 days)
  • b. Malathion lotion (Ovide) Also repeat treatment in 9 days
  • c. Pyrethrin (A-200, RID) with piperonyl butoxide-containing shampoo. Permethrin (Nix)
  • d. Remove nits with a fine-toothed comb.
  • e. Treat all close contacts and family members. Clean clothes and house
  • f. Bactrim DS-taken bid for 3 days, repeat in 1 wk (10mg/kg)
  • g. Treatment resistance to all therapy becoming a problem.
  • h. Clear 1,2,3 (oil of anise)
  • i. PawPaw Tree Lice Remover Shampoo
  • j. Suffocation – e.g., 5% benzyl alcohol lotion (Ulesfia)
  • k. Coming soon: Spinosad – a neurotoxin derived from a soil fungus
  • l. Topical – ivermectin (Sklice) x1
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13
Q

Body Lice 101

  • Natural Hx
  • Pathophys
  • Physical Findings
  • Treatment
A

Pediculosis corporis

Natural history

  • a. A disease of vagrants or persons with poor hygiene who rarely change or launder clothing
  • b. Transmitted by infected clothing or bedding
  • c. A major vector in epidemic typhus, trench fever, relapsing fever

Pathophysiology

  • a. Caused by infestation with Pediculus humanus variant humanus b.
  • Lice live in seams of clothing and are only found on the skin when feeding. Nits are attached to cloth fibers on clothing.
  • c. Sensitization to lice and their products contributes to signs and symptoms of infestation.
  • d. Secondary bacterial infection frequently occurs.
  • e. Nits may remain viable as long as 1 month. Lice die in 2-10 days without a blood meal.

Physical findings

  • a. Louse bites start as red macules with a central punctum which rapidly become papular and are quickly excoriated.
  • b. Lesions are most common about shoulders, interscapular areas, trunk, buttocks.
  • c. With long-standing infestation, can see a crusted, eczematous widespread dermatitis, thickened, dry, scaling, hyperkeratotic, hyperpigmented skin.
  • d. Nits and lice are found in seams of clothing.

Treatment

  • a. Clothing must be treated with lindane, or sterilized, washed, and ironed, or stored in plastic for 30 days.
  • b. Pyrethrums-sprayed onto clothing another option.
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