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I3 Exam 3 > Ectoparasites (Diemert) > Flashcards

Ectoparasites (Diemert) Flashcards

1
Q

Name two infestations with parasites that live on or in the skin (common to US)

A

Scabies (sarcoptes scabiei) and pediculoses (lice)

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2
Q

Name three infestations with parasites that live on or in the skin (seen in travelors)

A

Tungiasis, myiasis, cutaneous larva migrans

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3
Q

Common characteristics of ectoparasites

A

do not cause significant disease, higher prevalence in vulnerable groups, elicit strong inflammatory and immune response (not protective)

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4
Q

Sarcoptes scabiei transmission

A

person-to-person; fomites (towels, clothes); sexually transmitted

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5
Q

Sarcoptes scabiei mechanism (eggs and immune response)

A
  • female burrows into dermis and lays eggs; hatch in 3-4 days
  • Type IV hypersensitivity reaction to MITES AND EGGS
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6
Q

Sarcoptes scabiei clinical manifestation

A
  • intense pruritus 3-4 weeks (sooner after re-infestation)
  • erythematous papular, vesicular, pustular lesions
  • short, serpiginous burros (2-3 mm) in hands, feet, wrist, waistline, genitals
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7
Q

Sarcoptes scabiei diagnosis

A
  • microscopic exam of skin scrapings

- burrow ink-test

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8
Q

Sarcoptes scabiei treatment

A
  • topical permethrin cream (treat 2x 1 week apart because eggs hatching); treat entire house and sexual contacts; apply to whole bodt
  • oral: ivermectin (single oral dose, repeat after 1 week)
  • wash linens with hot water
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9
Q

What is crusted or Norwegian scabies?

A
  • affects immunocompromised (HIV, HTLV, alcoholic)
  • affects entire dermis
  • hypertrophic rxn
  • NOT pruritic (less inflam)
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10
Q

What is nodular scabies?

A
  • usually on genitals, axillae, but, areolae

- resolves w/ post-inflamm. hyperpigmentation

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11
Q

Pediculoses (lice) mechanism

A
  • hairy parts of body: female deposit eggs/nits on emerging hair shaft (nits hatch after 6-10; resulting nypmh develop into adults in 10 days; adults live for 1-3 months)
  • feed on human blood; dies within 24 hours w/o host
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12
Q

Pediculoses capitis (head lice) clinical

A

-pruritus: hypersensitivity to feeding adult lice saliva

secondary bacterial infection due to scratching

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13
Q

Pediculoses capitis (head lice)

A

visualize nits or lice

-Wood’s lamp: live nits fluoresce

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14
Q

Pediculoses capitis treatment

A

topical pediculocides

  • gels, lotions, creams or foams better than shampoos bc longer contact time
  • pyrethroids, malathion do not kill nits so need to re-treat after 7-10 days
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15
Q

Pediculoses corporis (body lice) mechanism

A
  • person-to-person transmission
  • poor socioeconomic conditions and crowding
  • found on clothing (adults attach to skin only to feed)
  • vector for epidemic typhus and relapsing fever
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16
Q

Pediculoses corporis clinical and treatment

A

same as head lice

-pruritus: hypersensitivity to feeding adult lice saliva
(secondary bacterial infection due to scratching)

topical pediculocides

  • gels, lotions, creams or foams better than shampoos bc longer contact time
  • pyrethroids, malathion do not kill nits so need to re-treat after 7-10 days
17
Q

Pediculoses pubis (Phthirus pubic; crabs) overview

A
  • nits/adult lice attach to hair
  • person-to-person (not prevented by condoms)
  • clinical: pruritus
  • treatment: topical pediculocides (retreat after 7-10 days); treat sex partners; wash everything
18
Q

Cimex lectularius (common bedbug) characteristics

A
  • nocturnal (hide in furniture during day)
  • blood feeding (bites are in CLUSTERS)
  • symptomatic treatment: anti-histamines and topical corticosteroids
  • killed by heat but difficult
19
Q

Tungiasis (Jiggers, chigoes) characteristics

A
  • SAND flea
  • epidermis affected
  • usually feet, under toenails, webs
  • feeds on blood and tissue
  • travelors
20
Q

Tungiasis clinical and mechanism

A
  • papule w/ central black dot marking rear of flea; grows rapidly
  • painful, itchy
  • 2-21 days after penetration, shiny white eggs extrude
  • flea dies after 3-5 weeks after penetration
21
Q

Tungiasis treatment and complication

A
  • extraction

- secondary bacterial infection

22
Q

Myiasis (maggots) affected areas of world

A

-tropics

23
Q

Myiasis transmission

A
  • tumbu fly in southern Africa (eggs laid on damp linen; larvae hatch and penetrate skin when come into contact)
  • botfly in South, Central America (captures mosquito, lays eggs on its abdomen, then gets delivered to human during bite)
24
Q

Myiasis types

A
  • furuncular: most common, subq
  • wound: eggs laid on existing wound
  • cavitary: intestinal, urogenital (uncommon)
25
Q

Myiasis typical lesion (furuncular)

A
  • boil-like, non-healing, erythematous lesions
  • ooze when squeezed
  • central punctum (may see rear of bug)
  • pruritus and pain common (may feel larva moving within lesion)
26
Q

Myiasis management

A
  • asphyxiate larva (vaseline, nail polish, bacon)

- may need to surgically extract

27
Q

Myiasis prevention

A
  • mosquito repellent and bed nets (Americans)

- iron all clothing prior to wearing

28
Q

Myiasis if left untreated…

A

-larva emerges in 5-10 weeks, drops to ground and pupates

I3 Exam 3 (9 decks)

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