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Dermatology > Lice, Scabies, Spider Bites > Flashcards

Lice, Scabies, Spider Bites Flashcards

1
Q

Pediculosis

  1. What are they?
  2. What is head lice called?
  3. What is body lice called?
A
  1. Ectoparasites that live on the body and feed on human blood after piercing the skin.
  2. Pediculosis capitus: head lice
  3. Pediculosis corporis: body lice
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2
Q

Pediculosis
Clinical presentation?
3

A
  1. Pruritus
    - May take 2-6 weeks to develop after first exposure
  2. Itching and scratching can lead to secondary cellulitis
  3. Pubic lice should prompt evaluation for other sexually transmitted infections
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3
Q

Pediculosis

Dx? 3

A
  1. Observation of:
    Eggs (nits)
    Nymphs
    Mature lice
  2. Commonly found behind ears and on the back of the neck
  3. Wood lamp of area
    Yellow-green fluorescence of lice/nits
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4
Q

Pediculosis Treatment

1. Medication: Focus on two mechanisms? (which drugs go with these mechanisms?)

A 
Medication
Focus on 2 mechanisms
1. Neurotoxicity
-Permethrin 1% lotion (Nix) first-line
2. Suffocation via “coating”
-Benzyl alcohol 5% lotion (Ulesfia)
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5
Q

Which drug promotes hyperexcitation and death by paralysis?

A

Spinosad 0.9% (Natroba)

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6
Q

Environmental control

Treat all persons who have contact with infested patients (especially who?

A

Sexual partners

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7
Q

Sarcoptes Scabiei (Scabies)
1. What is it?
2. How do we find them?
2

A
  1. 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
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8
Q

Sarcoptes Scabiei (Scabies)

  1. May be transmitted from _____?
  2. Most often transmitted by what?
  3. Spread rapidly under crowded condition such as? 4
  4. Usually symptomatic after how long?
A
  1. May be transmitted from objects
  2. Most often transmitted by direct skin to skin contact

Higher risk with prolonged contact

  1. Spread rapidly under crowded conditions
    - Nursing homes
    - Extended care facilities
    - Prisons
    - Child care facilities
  2. Usually two to six weeks before become symptomatic
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9
Q

Sarcoptes Scabiei (Scabies)

  1. Common sites of mites?
  2. Common sites of rash? 7
A
  1. Creases in skin
    • Axilla
    • Stomach
    • Genitals
    • lower back/buttocks
    • elbows
    • knees
    • upper back
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10
Q 
Sarcoptes Scabiei (Scabies)
Classic scenario:

Itching:

  1. Caused by what?
  2. May be worse with what?
  3. Worse when?
  4. Watch for what?
A
  1. Caused by allergic reaction to the mites.
  2. Made worse by warmth
  3. Usually worse at night
  4. Watch for excoriation
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11
Q

Scabies
Types of lesions?
5

A
  1. Burrow- linear tunnel in which the mites live
  2. Papules
  3. blisters
  4. nodules
  5. eczematous
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12
Q

Scabies
Dx?
2

A
  1. Scraping off a tiny bit of skin

2. View under a microscope for mites or eggs

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13
Q
  1. Scabies treatment
  2. Apply where?
  3. Leave on for how long?
  4. Repeat when if necessary?
  5. Safe for children as young as what?
  6. SE? 4
  7. Treat who else? 2
A
  1. Permethrin Cream 5% 60 gram tube (preferred treatment)
  2. Apply from head to feet
  3. Leave on for 8-14 hours then wash with soap and water
  4. Repeat in 7 days if necessary
  5. Safe for children as young as 1 month old and pregnancy
  6. Side effects:
    - Mild to moderate burning and stinging
    - Itching
    - Rash
    - Redness
  7. Treat family members and sexual partners
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14
Q

Scabies treatment

Alternate medications? 2

A
  1. Lindane Lotion 1%

2. Oral Ivermectin

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15
Q

Lindane Lotion 1%

  1. Disadvantage?
  2. Most pts require what?

Oral Ivermectin

  1. Dosing?
  2. Do not use in who? 2
A

Lindane Lotion 1%

  1. Has more neurotoxicity than Permethrin
  2. Most patients require 30ml but larger adults up to 60ml

Oral Ivermectin

  1. 200mcg/kg by mouth as single dose with repeat dose in two weeks
  2. CDC recommends not using in pregnant or lactating women
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16
Q

Scabies
Can give something for the itching? 3

Watch for what?

A
  1. Atarax (Hydroxyzine) 10-25mg po every 4-6 hrs prn itching
  2. Benadryl 25mg po every 4-6 hrs prn itching
  3. Steroid cream

Secondary infections

17
Q
  1. How do spiders cause infection?

2. Which spiders are most likely to inflict medically significant bites? 2

A
  1. Use sharp fangs to bite prey and inject venom

Spider bites:
Rare medical events
Most pose no threat to humans

  1. Spiders most likely to inflict medically significant bites
    - Widow
    - Recluse

Common disorders can mimic a spider bite

18
Q
  1. How do widow spider bites look?
  2. What do they release?

Recluse

  1. Notorious for becoming what?
  2. What kind of reaction do they cause?
  3. What toxin do they release?
  4. Genus?
A
  1. Unremarkable local lesions
    - Characteristic systemic reaction
  2. Neurotoxin
    α- latrotoxin
  3. Notorious for becoming necrotic (rare)
  4. Systemic reaction mild
    - Nonspecific signs and symptoms
  5. Sphingomyelinase D
  6. Latrodectus genus
19
Q

Spider bites: Acute lesions can be what? 3

A
  1. Papule
  2. Pustule
  3. Wheal
20
Q

Widow spiders
Patient History
Recent less than 8hrs at risk activity
5

A
  1. Gardening
  2. Chopping wood
  3. Using outdoor furniture
  4. Cleaning a garage
  5. Moving into a house that has not been occupied recently
21
Q

Widow Spiders History findings?

3

A
  1. Bite usually on the extremities (especially lower)
  2. Most are initially asymptomatic or cause mild pain at the site
  3. Muscle pain is the most prominent feature in systemic reactions
22
Q

Muscle pain is the most prominent feature in systemic reactions.
How does it manifest?
3

Other symptoms may include? 3

A
  1. Extremity muscles
  2. Abdomen
  3. Back
  4. Tremor
  5. Weakness
  6. Shaking of the extremity
23
Q

Presentation of infants and children for widow bites?

4

A
  1. Nonspecific
  2. Distressed and inconsolable
  3. Refusing food and drink
  4. Generalized erythema
24
Q

Widow bites: Physical findings?

5

A
  1. Vital signs normal in 70% of patients

Musculoskeletal exam:
2. Intermittent muscle rigidity and

  1. tenderness adjacent to the bite
    OR abdomen, chest or back
  2. Weakness, tremor, and myoclonus
  3. Diaphoresis:
    Corresponds to affected muscle group
25
Q

Widow Physical findings:

Wound site & local symptoms 5

A
  1. Blanched circular patch
  2. Surrounding red perimeter
  3. Central punctum
  4. Appears like a “target” lesion
    - 50 percent of cases
26
Q

Widow bite Dx
1. Primarily based on what?

  1. Possible lab studies? 3
  2. Adults with cardiac risk factors consider? 2
A
  1. Primarily based on symptoms and signs with history
  2. No specific lab studies
    - Leukocytosis
    - Elevated creatinine
    - Elevated Liver enzymes
  3. Adults with cardiac risk factors consider:
    - EKG’s
    - Cardiac enzymes
27
Q

DDx for Widow bites? 6

A
  1. MRSA
  2. Surgical abdomen
  3. Lyme
  4. Myocardial ischemia or infarction
  5. Tetanus
  6. Rabies
28
Q

Envenomation
Mild presentation? 2
Moderate presentation? 4
Severe? 3

A

Mild

  1. Localized pain at bite
  2. Normal vital signs

Moderate

  1. Muscular pain in envenomated extremity
  2. Extension of muscular pain to chest or abdomen
  3. Local diaphoresis at bite
  4. Normal vital signs

Severe

  1. Generalized muscular pain in back, abdomen and chest
  2. Diffuse diaphoresis
  3. Abnormal vital signs
29
Q

Mild Envenomation treatment?

4

A
  1. Local measures: Gently clean the bite with mild soap and water
  2. Oral analgesia:
  3. Oral muscle relaxers:
  4. Tetanus prophylaxis if indicated
30
Q

Mild Envenomation treatment:
1. What would you use for oral analgesia?
3

  1. What would you use for oral muscle realxers? 2
A
    • Acetaminophen
    • Ibuprofen
    • Oxycodone or hydrocodone
    • Benzodiazepines (Valium)
    • Methocarbamol (Robaxin)
31
Q

Moderate to Severe Envenomation treatment?

5

A
  1. Local wound care and tetanus prophylaxis as for mild envenomation
  2. Parenteral opioids (e.g. morphine)
  3. Parenteral benzodiazepines (e.g. lorazepam) to reduce the frequency and severity of muscle spasms
  4. Antiemetic therapy (e.g. Sublingual or intravenous ondansetron)
  5. Consider Antivenom administration
    - Consult with medical toxicologist prior to administration
    - Carries small risk of anaphylactic reactions
32
Q

Brown Recluse

  1. Where do you usually sustain the bite?
  2. Typically appear where? 3
  3. Notorious for what?
  4. FOund where? 3
  5. Produces what?
  6. Genus?
A
  1. Bites are usually sustained indoors
  2. Typically on
    - upper extremities,
    - thorax or
    - inner thigh
  3. Notorious for sometimes causing skin necrosis
  4. South, West, and Midwest areas
  5. Cytotoxic enzymes
  6. Loxosceles
33
Q
  1. Brown recluse local symtpoms? 4

2. Systemic? 4

A

Local Symptoms:

  1. Usually develop two to eight hours after a bite.
  2. Usually painless initially
  3. Occasionally some minor burning that feels like a bee sting
  4. Severe pain at bite site after about four hours

Systemic symptoms:

  1. Malaise
  2. Nausea & Vomiting
  3. Fever
  4. Myalgias
34
Q

Brown Recluse physical findings?

5

A
  1. Initially bite site is mildly red
  2. May reveal fang marks
  3. Blistering (common)
  4. Necrosis of skin and subcutaneous fat (less common)
  5. Severe destructive necrotic lesions with deep wide borders (rare)
35
Q

Brown Recluse Dx?
Based on? 2

Definitive Dx? 2

If both these conditions are not met what must you do?

A
  1. Based most often on:
    - History
    - Clinical presentation
  2. Definitive:
    - A spider was observed inflicting the bite
    - Spider recovered, collected, and properly identified by an expert entomologist
  3. If both conditions are not met, then other conditions must be excluded.
36
Q

Brown Recluse DDx?

10

A

Numerous conditions mistaken for recluse spider bite

  1. Bacterial
  2. Deep fungal
  3. Pseudomonas aeruginosa
  4. Parasitic
  5. Viral
  6. Topical and exogenous causes
  7. Venous
  8. Neoplastic disease
  9. Necrotizing vasculitis
  10. Diabetic ulcers
37
Q

Brown recluse treatment

5

A
  1. Local wound care
  2. Pain management with
    NSAIDS or opioids if necessary
  3. Tetanus prophylaxis if indicated
  4. Dapsone in some cases to prevent progression to necrosis & reduce pain
  5. No Antivenom available in the United States
38
Q

What would you do for local wound care for a brown recluse?

3

A
  1. Clean with mild soap and water
  2. Apply cold packs
  3. Maintain affected part in elevated or neutral position

Dermatology (12 decks)

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