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DERM > LICE SCABIES SPIDER BITES > Flashcards

LICE SCABIES SPIDER BITES Flashcards

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Dermatology Board Prep flashcards
1
Q

pediculosis

A

lice

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2
Q

Ectoparasites that live on the body and feed on human blood after piercing the skin

A

lice (pediculosis)

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3
Q

head lice
body lice
pubic lice

A

pediculosis capitis
pediculosis corporis
pediculosis pubis

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4
Q

life cycle of lice

A

unhatched egg(nit), three molt stages(growing), adult reproductive stage, death

live about 30-50 days
lay about 150-300 eggs per life cycle

feed on human host blood

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5
Q

body lice

A

can live much longer off of a host than head lice

head lice feed off of human blood - only last a few hours off of host

body lice can live up to 14 days off of a host; Transferred mostly through infested clothes, blankets

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6
Q

pubic lice

A

spread through intimate contact

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7
Q

head lice

A

Incidence is higher among girls. Being spread from combs and hats is not the usual mode. It is mostly hair to hair contact.

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8
Q

CLINICAL PRESENTATION OF LICE

A

⦁ pruritus (make take 2-6 weeks to develop after exposure)
⦁ itching & scratching can lead to secondary cellulitis
⦁ pubic lice = should prompt eval for other STIs
⦁ typical lesion of body lice = macule at bite site that may develop vesicles/wheals
⦁ nocturnal pruritus = common

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9
Q

DIAGNOSIS OF LICE

A

Observation of:
⦁ Eggs (nits)
⦁ Nymphs
⦁ Mature lice

Commonly found behind ears and on the back of the neck

Wood lamp of area
⦁ Yellow-green fluorescence of lice/nits

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10
Q

1st line tx for lice

A

permethrin (Nix)

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11
Q

lice treatment

A
  • 2 mechanisms
    o Neurotoxicity
    ⦁ Permethrin (Nix) = 1st line
    ⦁ Malathion

o Suffocation via “coating”
⦁ benzyl alcohol lotion (Ulesfia)

  • Spinosad (Natroba) = promotes hyperexcitation & death by paralysis

Environmental control = treat all ppl in contact with infested patient (especially sexual partners), then nit combs

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12
Q

SCABIES

A

Sarcoptes Scabiei (scabies)
From Latin: “to scratch”
Also known as the seven year itch
Contagious infection caused by the mite Sarcoptes Scabiei.
Tiny and usually not directly visible
Parasite that burrows under the host’s skin causing intense itching

After female mite is pregnant she burrows under the skin to lay her eggs.

She lays 2-3 eggs each day for 4-5 weeks. Eggs hatch and migrate to skin surface and continue to burrow back into skin for food and protection

Mites usually contracted by close contact with infected persons or fabrics. They can only live up to 2 days off of host in sheets, bedding, fabrics.
(can’t just get scabies from touching infected person, need CLOSE contact with infected person

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13
Q

three most common skin disorders in children

A

pyoderma
tinea
scabies

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14
Q

how long before scabies pt becomes symptomatic

A

2-6 weeks

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15
Q

scabies most often transmitted by

A

direct skin to skin contact

Higher risk with prolonged contact

Spread rapidly under crowded conditions
Nursing homes
Extended care facilities
Prisons
Child care facilities
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16
Q

scabies: where are mites present, and where is rash present

A

MITES are usually present at wrists and fingers

RASH present in underarms, abdomen, groin, back, buttock crease, elbows, knees

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17
Q

classic presentation for scabies

A

⦁ itching*** - caused by allergic rxn to mites
⦁ itching made worse by warmth
⦁ itching usually worse at night
⦁ watch for excoriations

  • look for burrowing type of lesion - linear tunnel where mite lives; skin lesions commonly in web spaces, flexor surface of wrists, axillae, waist, feet and ankles
  • facial & palmoplantar involvement = unique to infantile scabies
  • itching = most severe at night
  • itching takes about 4-6 weeks to develop in others
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18
Q

NORWEGIAN SCABIES

A
  • not very itchy
  • all over body - warty / scales / crusts
  • malodorous
  • nails affected

A severe form of scabies. It will usually involve millions of mites.

Conditions that compromise cellular immunity, such as acquired immunodeficiency syndrome (AIDS), human T cell lymphotropic virus type 1 (HTLV-1) infection, leprosy, and lymphoma.

The scalp, hands, and feet are particularly susceptible. If untreated, the disease usually spreads to entire skin. Scales become warty, especially over bony prominences. Crusts and fissures appear. The lesions are malodorous. Nails are often thickened, discolored, and dystrophic. Pruritus may be minimal or absent (body has shut off response)

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19
Q

Norwegian scabies more found in conditions such as

A

AIDS
HTLV-1 (human T cell lymphotropic virus type 1)
Leprosy
Lymphoma

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20
Q

diagnosis of scabies

A

Scraping off a tiny bit of skin; View under a microscope for mites or eggs

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21
Q

treatment of scabies

A

permethrin

Apply from head to feet
Leave on for 8-14 hours then wash with soap and water
Repeat in 7 days if necessary
Safe for children as young as 1 month old and pregnancy
Treat family members & sexual partners

Can give something for the itching:
⦁ Atarax (Hydroxyzine) 10-25mg po every 4-6 hrs prn itching
⦁ Benadryl 25mg po every 4-6 hrs prn itching

steroid cream

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22
Q

SE of permethrin

A

Mild to moderate burning and stinging
Itching
Rash
Redness

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23
Q

more effective than Lindane but less effective than permethrin

A

ivermectin

24
Q

has more neurotoxicity than Permethrin

A

Lindane lotion

25
Q

alternative treatments for scabies other than Permethrin

A

⦁ Lindane Lotion = has more neurotoxicity than Permethrin; apply thin layer of lotion & massage in from neck to toes. leave 8-12 hours, then bathe

⦁ Ivermectin = more effective than lindane lotion, but less effective than permethrin. Take 200mcg/kg by mouth - single dose. repeat dose in 2 weeks. CDC recommends NOT using in pregnant or lactating women

26
Q

treatment for crusted scabies (Norwegian scabies)

A

have to use both Permethrin & Ivermectin

27
Q

spiders most likely to inflict medically significant bites

A

⦁ Widow
⦁ Recluse
⦁ Hobo
⦁ Tarantulas - throw their hairs.

28
Q

TARANTULAS

A
  • Non-aggressive - have fangs but rarely bite
  • when threatened - dislodge small barbed hairs from posterior of their abdomen and launch them at attacker
  • urticating hairs, as well as airborne material from crushed tarantulas, may cause irritation if they come in contact with skin, eyes or mucous membranes
  • urticarial hairs = also common in certain plants (stinging nettles) & certain caterpillars
  • can cause localized skin urticarial reactions as well as eye issues if hairs lodge in cornea
29
Q

treatment for tarantula bites / urticarial rxns

A

o Bites
- most bites will cause local pain & local rxn without any significant systemic issues; risk = higher from secondary inoculation of infection from bite, or if pts scratch or mistreat the bite wound

o Urticarial Rxns = best treated with antihistamines and topical steroids if needed
- eye issues = refer to ophthalmologist for eval / hair removal

30
Q

Every spider bite = need to evaluate the victim’s

A

tetanus shot status

31
Q

black widows Release neurotoxin called

A

Alpha-Latrotoxin

released by all Latrodectus genus

32
Q

widow spiders

A
  • worldwide
  • unremarkable local lesions
  • characteristic systemic reaction
  • not all are black
  • Release neurotoxin called Alpha-Latrotoxin - released when they bite you - Latrodectus genus
  • mostly found outside
33
Q

patient hx with widow spider bite

A

recent “at risk” activity < 8 hrs

Gardening
Chopping wood
Using outdoor furniture
Cleaning a garage
Moving into a house that has not been occupied recently
34
Q

red hourglass on abdomen

A

black widow

35
Q

most prominent systemic reaction feature with black widow bite

A

MUSCLE PAIN****

o Other symptoms
⦁ tremor
⦁ weakness
⦁ shaking of the extremity

36
Q

symptoms with black widow bite

A

MUSCLE PAIN - extremity / abdomen / back

  • tremors
  • weakness
  • shaking of the extremity that was bitten
37
Q

PE OF BLACK WIDOW BITE

A

normal VS in 70% of patients

  • MSK exam = intermittent muscle rigidity & tenderness adjacent to bite - may also have this at abdomen, chest or back;
  • weakness, tremor, myoclonus.
  • Diaphoresis
38
Q

black widow bite

A
  • blanched circular patch with surrounding red perimeter & central punctum
  • appears like a “target” lesion in 50% of cases
39
Q

diagnosis of black widow bite

A
  • primarily based on symptoms & signs with hx
  • no specific lab studies
    ⦁ leukocytosis
    ⦁ elevated creatinine
    ⦁ elevated LFTs
  • In adults with cardiac risk factors = consider
    ⦁ EKG
    ⦁ Cardiac enzymes
40
Q

lab results for black widow bite

A

leukocytosis
elevated LFTs
elevated creatinine

if cardiac risk factors = consider getting an EKG and cardiac enzymes

41
Q

MILD / MOD / SEVERE ENVENOMATION WITH BLACK WIDOW BITE

A

o Mild
⦁ Localized pain at bite
⦁ Normal vital signs

o Moderate
⦁	Muscular pain in envenomated extremity
⦁	Extension of muscular pain to chest or abdomen
⦁	Local diaphoresis at bite
⦁	Normal vital signs

o Severe
⦁ Generalized muscular pain in back, abdomen and chest
⦁ Diffuse diaphoresis
⦁ Abnormal vital signs

42
Q

treatment for black widow bite

A

o Mild envenomation
⦁ gently clean bite with mild soap & water
⦁ Oral analgesic (acetaminophen, ibuprofen, oxycodone or hydrocodone)
⦁ oral muscle relaxer (benzo - valium, Methocarbamol - Robaxin)
⦁ Tetanus prophylaxis if indicated

o Mod / Severe Treatment
⦁ local wound care - clean with soap / water
⦁ tetanus prophylaxis if indicated
⦁ parenteral opioids (morphine)
⦁ parenteral benzos (lorazepam) to reduce frequency & severity of muscle spasms
⦁ antiemetic therapy (sublingual or IV ondansetron)
⦁ consider antivenom administration - consult with medical toxicologist - small risk of anaphylactic reactions

43
Q

notorious for becoming necrotic

A

brown recluse bite

44
Q

brown recluse spider

A
  • looks like a violin in the center
  • in north & south America
  • notorious for becoming necrotic
  • Loxosceles genus
  • brown
  • releases Sphingomyelinase D - unique to Loxosceles genus - causes necrosis
  • systemic reaction is mild - nonspecific signs & sympoms

Bites are usually sustained indoors
typically on upper extremities, thorax or inner thigh
south, west and midwest areas
notorious for sometimes causing skin necrosis
cytotoxic enzymes

45
Q

brown recluse symptoms

A
  • symptoms usually develop 2-8 hrs after a bite
  • usually initially painless, some have minor burning like a bee sting
  • after about 4 hours = severe pain at bite site
SYSTEMIC SYMPTOMS
⦁	malaise
⦁	Nausea / vomiting
⦁	fever
⦁	myalgias
46
Q

brown recluse bite appearance

A
  • initially, bite = mildly red, may reveal fang marks
  • blistering = common
  • necrosis of skin & subcutaneous fat (less common)
  • severe destructive necrotic lesions with deep wide borders (rare)
47
Q

diagnosis of brown recluse bite

A

DIAGNOSIS
- based on hx & clinical presentation

  • Definitive diagnosis = a spider was seen biting the pt & spider was collected & properly identified by expert entomologist

If both conditions are not met, then other conditions must also be excluded

48
Q

brown recluse treatment

A
  • clean local wound with mild soap & water, apply cold packs and maintain affected part in elevated or neutral position
  • Pain management
    ⦁ NSAIDS or opioids if necessary
  • Tetanus prophylaxis if necessary
  • Dapsone in some cases to prevent progression to necrosis & to reduce pain
  • no antivenom available in the US
49
Q

HOBO SPIDER

A
  • native to Europe
  • introduced to northwestern US - found primarily in Washington, Oregon, Wyoming, Colorado, Utah & Montana

venomous spider in Pacific northwest = Eratigena agrestis

Live in dark areas close to the ground = Woodpiles & Basements

Identification

  • lack colored bands around leg joints
  • abdomen has a yellow V-shaped pattern down the middle
  • have light stripe running down the middle of the sternum
50
Q

most common hobo bite symptom

A

SEVERE HEADACHE**

51
Q

SYMPTOMS OF HOBO BITE

A

severe headache
nausea / vomiting
lethargy
diarrhea

52
Q

hobo bite

A
  • bite similar to brown recluse, but necrosis is RARE
  • bite = involves induration of skin & expanding erythema
  • the wound blisters & ruptures
  • healing occurs gradually over 45 days
53
Q

bite = eschar

A

hobo

54
Q

the allergenic compound found in poison ivy, poison oak, and poison sumac

A

urushiol

55
Q

most common presenting signs of dermatoses - plants

A

erythema & pruritus

56
Q

plant dermatoses treatment

A

oatmeal baths and cool, wet compresses. Topical astringents such as Burrow’s solution used under occlusion may be useful to dry weeping lesions.

Oral antihistamines are commonly used to try to reduce pruritus. However, the itching in poison ivy dermatitis is not caused by histamine release.

High-potency topical corticosteroids are most helpful early in allergic contact dermatitis. Severe dermatitis, particularly involving the face or genital region, may require systemic corticosteroids

DERM (12 decks)

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