02-17 Infestations

Question 1

This lecture has tons of pictures

Answer 1

Review them!

Question 2

Scabies causative organism and life cycle

Answer 2

.

Question 3

Scabies Sites of Infestation

Answer 3

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

Question 4

Dx Scabies

Answer 4

mineral oil on finger webs, scrape and look

OR

spray with ink, wait, wipe off

OR

ELISA

Question 5

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

Answer 5

No hair! (hopefully)

Question 6

Tx scabies?

Answer 6

1. permetherin (from crushed chrysanthemums)
2. malathion

Treat all close personal contacts

Question 7

Variants of lice infestation

Answer 7

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

Question 8

Txing lice

Answer 8

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

Question 9

How are body lice transmitted vs. head lice?

Answer 9

body lice are transmitted by fomites! groooooosss

Question 10

Public Lice 101

• Transmission
• Pathophys
• Physical Findings
• Treatment

Answer 10

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

Question 11

Scabies 101

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

Answer 11

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.
• 3. Lesions are intensely pruritic, especially at night.
• 4. Eczematous changes are the primary expression of the problem.
• 5. 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

Question 12

Head Lice 101

• Natural Hx
• Pathophys
• Physical Findings
• Tx

Answer 12

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

Question 13

Body Lice 101

• Natural Hx
• Pathophys
• Physical Findings
• Treatment

Answer 13

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.