02-17 Infestations Flashcards
Goal: To introduce two common skin problems caused by infestations
This lecture has tons of pictures
Review them!
Scabies causative organism and life cycle
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Scabies Sites of Infestation
- flexor wrist
- extensor elbow
- between fingers, toes
- breast
- butt
- genitals
- waist
Dx Scabies
mineral oil on finger webs, scrape and look
OR
spray with ink, wait, wipe off
OR
ELISA
Why can’t you get folliculitis on your soles/palms?
No hair! (hopefully)
Tx scabies?
- permetherin (from crushed chrysanthemums)
- malathion
Treat all close personal contacts
Variants of lice infestation
- Head Lice - Pediculus humanus var. capitis
- Body Lice - Pediculus humanus var. humanus
- Crabs - Phthirus pubis
Txing lice
- permetherin (RID) or malathion (OVIDE) shampoo
- nit comb
- bactrim - kills commensals that lice feed on for B Vitamins
How are body lice transmitted vs. head lice?
body lice are transmitted by fomites! groooooosss
Public Lice 101
- Transmission
- Pathophys
- Physical Findings
- Treatment
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
Scabies 101
- Natural Hx
- Pathophysiology
- Physical Findings
- Variations
- LAb Findings
- DDx
- Tx
- Public Health Tx
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
- 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.
- Lesions are intensely pruritic, especially at night.
- Eczematous changes are the primary expression of the problem.
- 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
Head Lice 101
- Natural Hx
- Pathophys
- Physical Findings
- Tx
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
Body Lice 101
- Natural Hx
- Pathophys
- Physical Findings
- Treatment
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.