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Pharmacotherapy > Lice and Scabies > Flashcards

Lice and Scabies Flashcards

1
Q

What are the types of lice?

which are vectors of disease

A

head, pubic/crabs, body lice
head/pubic not vectors for disease
body lice are vectors for disease: typhus, relapsing fever, trench fever, endocarditis
- poor hygiene is a major factor

  • children 3-12 are most commonly affected
  • infestations peak b/w august and nov
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2
Q

signs/symptoms of lice

A
  • presence of white specs
  • itching (not always present the 1st time, common on back and sides of scalp, cause bacterial infection as they create wounds)
  • irritation
  • red marks
  • sores
  • fever
  • fatigue
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3
Q

where is lice found?

A
  • head and pubic on skin surface
  • body lice found on seams of clothing
  • nits of head and pubic lice are generally found at the base of hair shafts
  • formal diagnosis requires detection of live louse
  • verify with a HCP
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4
Q

life cycle of the louse?

A
  • life cycle of female louse 30 days
    lay 7-10 eggs daily
  • hatch after 8-10 days and mature in 8-15 days for head and body, 14-22 days for pubic lice
  • obligate human parasites - survive 3-4 days away from body
  • nits can survive away for up to 10 days
  • retreat 7-10 days
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5
Q

explain wet-combing

A
  • wet hair and apply a white conditioner
  • examine scalp and hair in areas of good lighting, may use a magnifying glass to aid in visualization of live lous or nits
  • fine tooth comb, comb entire head beginning at scalp (repeat at least 5x)
  • examine combs after each stroke for presence of louse/nits
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6
Q

Goals of therapy (4)

A
  • elim lice infestation
  • relieve itch
  • prevent transmission
  • prevent secondary bacterial infection
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7
Q

Name 4 treatment options

A
  • permethrin 1% (Nix, Kwellada-P)
  • pyrethrins with piperonyl butoxide (R&C)
  • isopropyl myristate 50% w/w cyclomethicone 50% (Resultz)
  • dimeticone 50% (NYDA)
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8
Q

Permethrin 1% (Nix, Kwellada-P)

Class
Schedule
MOA
Precautions
Contraindication
Directions for use
Side effects
Efficacy
Resistance
A

Class: synthetic pyrethroid
Schedule: II
MOA: Disrupts Na channel → delayed repolarization of membrane potential → respiratory paralysis
Precautions: not for children <2 mos

Contraindication: Allergies to ragweed/chrysanthemum

Directions for use
Wash hair with conditioner-free shampoo
Apply permethrin 1% to damp hair.
Leave on for 10 mins then rinse
Retreat in 7 days
(2 bottles may be needed for thick/long hair)

Side effects: transient irritation (redness, swelling), ocular toxicity, burning, stinging, rash, tingling, numbness uncommon

Efficacy: 96-100%, good ovicidal activity (70-80%)

Resistance: 99% of North American lice may have genes that are consistent with resistance (insectide MOA)

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9
Q

Pyrethrins with Piperonyl Butoxide (R&C)

Class
Schedule
MOA
Precautions
Contraindication
Directions for use
Side effects
Efficacy
Resistance
A

Class: Insecticide extracted from chrysanthemum
Schedule: II
MOA: Disrupts Na channel → delayed repolarization of
membrane potential → respiratory paralysis
- Piperonyl butoxide inhibits pyrethrin breakdown

Precautions: Avoid contact with eyes or mucosal tissues

Contraindication: Allergies to ragweed/chrysanthemum, petroleum pdts

Directions for use
Apply to DRY hair
Leave on for 10 mins then lather and rinse with water
Repeat in 7 days

Side effects: Mild irritation, Potential for contact dermatitis due to petroleum distillates used in formulation

Efficacy: • 45% after 1st application. 94% after 2nd application, may have some ovicidal activity

Resistance: 99% of North American lice may have genes that are consistent with resistance (insectide MOA), potential cross-resistance with permethrin

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10
Q

Isopropyl myristate 50% w/w
cyclomethicone 50 % (Resultz)

Class
Schedule
MOA
Precautions
Contraindication
Directions for use
Side effects
Efficacy
Resistance
A

Class: Non-insecticide
Schedule: II
MOA: Dissolves louse exoskeleton → dehydration →
death

Precautions: Not recommended in children < 2 years
• Avoid contact with eyes
• Formulation is volatile and flammable

Contraindications: none

Directions for use
Apply to DRY hair
Leave on for 10 mins then lather and rinse with water
Repeat in 7 days

Side effects: Local irritation (mild redness and itching)

Efficacy: 57-93%, no ovicidal activity

Resistance: Unlikely (physical mechanism of action)

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11
Q

Dimeticone 50% (Nyda)

Class
Schedule
MOA
Precautions
Contraindication
Directions for use
Side effects
Efficacy
Resistance
A

Class: Non-insecticide
Schedule: II
MOA: Suffocation through blockage of spiracles
• Gut rupture from inhibition of water excretion

Precautions: Not recommended in children < 2 years
• Avoid contact with eyes
• Formulation is volatile and flammable

Contraindications: none

Directions for use
Spray on DRY hair and massage until hair is
completely wet
Leave solution on hair
After 30 mins comb hair with fine-toothed comb
Leave on for at least 8 hrs before washing
Repeat treatment in 8-10 days

Side effects: Mild skin/scalp irritation
• Irritation if in contact with eyes

Efficacy: 97% cure rate
• 1 in 3 more patients lice free compared to permethrin
• 100% Ovicidal activity but 2nd application still
recommended due to imperfect application

Resistance: Unlikely (physical mechanism of action)

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12
Q

Gamma benze hexachloride (Lindane)

A
  • pediculocid, causes louse paralysis
    45-70% ovicidal
  • possible neurotox and bone marrow suppression
  • carcinogenic, removed from market
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13
Q

Benzyl alcohol 5% lotion

A
  • pt >6 mos (safety over 60 not established)
  • MOA: stun spiracles open so solution can enter and suffocate louse
  • not ovicidal
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14
Q

What are some natural treatments?

evidence?

A

Tea tree oil” antimicrobial/antiseptic

Mayo/olive oil: suffocate louse

Vaseline/cetaphil cleanser: suffocate louse

all have no evidence

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15
Q

Other non-drug measures for lice?

A

bug busting

  • comb wet hair for 30 mins, every 3-4 days a week
  • difficult to adhere to, time consuming

LouseBuster

  • dessication through application of hot air for 5 mins
  • expensive machine, needs training
  • hair dryer should not be used as it can blow away lice
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16
Q

How can lice get transmitted?

A
  • direct contact with infested humans or fomites
    fomites: brushes, combs, hats, hair clips, towels
  • all members of household should be examined, only bed maters and others confirmed should be treated
  • tell possible contacts
  • pets cannot transmit it
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17
Q

Cleaning procedures

A
  • retreat in 7-10 days

soak combs/brushes

  • in hot water for 5-10 mins
  • rubbing alcohol for 20 mins
  • Lysol 2% for 1 hr

wash bedding/clothing/toys

  • hot water and dry for 15 mind
  • fry clean
  • store in sealed plastic bag for 2 wks
  • store in sealed plastic bag in freezer overnight

vacuum carpets/furniture

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18
Q

Counselling pts

  • what type of comb?
  • when can children return to school?
A
  • nit picking in conjunction w/ medicated shampoos
  • back-comb hair with fine-toothed metal comb
  • pick nits with tweezers
  • recheck hair after 1-2 days of final treatment
  • children can return the day after 1st treatments
  • pediculocide sprays not recommended
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19
Q

what to do if very itchy or secondary infection?

A

itch -very bothersome and cause injury to skin surface
- antihistamines, topical corticosteroid

secondary infection - lesions caused by itching
- topical antibiotics, may need systemic

20
Q

what are some reasons of treatment failure?

A
  • non-adherence to instructions
  • failutre to retreat or re-application too soon
  • poor nit removal technique
  • pediculocide resistance
  • misdiagnosis
  • repeated exposure
21
Q

Body lice

signs and symptoms
diff diag
how to treat

A

signs and symptoms

  • erythematous papules with central puncture pt on areas where seam of clothing contacts skin
  • blue coloured macules (maculae cerulae)
  • noctural itching

diff diagnosis: seb derm, insect bites, eczema, impetigo, folliculitis

drug treatment not required

careful cleaning of clothes

  • hot water and dryer
  • iron seam of clothing is where lice likely live
  • seal in plastic bag for 2 wks
22
Q

Pubic lice

signs and symptoms
diff diag
how to treat

A

signs

  • similar to head and body lice
  • mostly in pubic area, can be eyelashes/brows, beard, axillae

diff diagnosis: seb derm, folliculitis, dermatophytosis

treatment similar to head lice (permethrin and pyrethrins with piperonyl butoxide)

all sexual contacts should be treated

23
Q

lice in eyelashes

how to treat?

A
  • remove with tweezers
  • apply Vaseline BID for 10 days to suffocate
  • more data needed for olive oil and mayo
24
Q

pregnancy and lactation

A

compatible with permethrin 1% and pyrethrins with piperonyl butoxide

no data for isopropyl myristate cyclomethicone or dimeticone

25
Q

monitoring

A

monitor daily for 2 weeks
monitor for itch - can recommend antihistamines or topical corticosteroids
monitor for secondary infections - antibiotics

26
Q

Scabies - epidemiology

A
  • Sarcoptes scabiei
  • prevalent in crowded living conditions
  • women and children more commonly affected than men (behavioural)
  • incidence higher in winter than summer
  • close personal contact
27
Q

scabies life sycle

A
  • female fertilized once on human host
  • male mites live close to skin surface and dies shortly after mating with female
  • female burrows into strateum corneum to lay eggs (2-3 daily) and remains here and continues to lay eggs for the remainder of lifespan (4-6 weeks)
  • eggs hatch 3-4 days
  • adult stage reached in 2-3 wks
  • pt generally have 10-12 mites
  • may survive off of host 2-36 hrs
28
Q

scabies signs and symptoms

where is it located in body?

A
  • intense itch at night
  • burrows (white/grey lines on skin surface
  • erythematous papules/vesicles
  • excoriations
  • pustules
  • furunculosis
  • impetigo
  • generally not found above neck but may occur in infants/young children with sever infestations
  • often b/w fingers and wrists
29
Q

crusted scabies (Norwegian Scabies)

A
  • immunocompromised pts
  • more contagious form of scabies
  • mild/absent itchy
  • hyperkeratosis of skin, hands, feet, scalp
  • malodourous lesions
  • infested w/ hundreds and thousands of mites
  • difficult to treat
  • high mortality rate due to secondary infections and sepsis
  • ivermectin PO and permetrhin 5%
30
Q

diagnosis of scabies

diff diagnosis

A
  • generally hard to see w/ naked eye
  • diagnosis should be made by physician
  • physician detects burrows w/ topical ink/skin scrapings
  • signs of mite, egg, fecal material = positive

diff diag:
- contact derm, eczema, psoriasis, fle bites, syphilis, heat rash, impetigo

31
Q

scabies goals of therapy (4)

A
  • exterminate parasites
  • relieve itch
  • prevent spread of infestation
  • prevent secondary bacterial infection
32
Q

Name 3 treatment options for scabies

A

permetrin 5%

crotamition 10% (Eurax)

sulfur 5-10%

33
Q

Scabies - Permethrin 5% (Nix, Kwellada-P)

Which line of treatment?
Schedule
Precautions
Contraindication
Directions for use
Side effects
A

Drug of choice, most effective scabicide
Schedule: II

Contraindication: Allergies to ragweed/chrysanthemum

Directions for use
Take a tepid bath/shower and towel dry
Apply to ENTIRE body from neck down including
fingernails, waist and genitalia (entire head and neck in
infants and young children)
Put on clean clothing
Wash off after 8-14 hrs
Second administration 1 week later often routinely prescribed but may not be necessary

Side effects: Pruritus, edema, erythema

Precautions: Preferred treatment in those > 2 months of age

34
Q

Scabies - Crotamiton 10% (Eurax)

Which line of treatment?
Schedule
Precautions
Contraindication
Directions for use
Side effects
A

2nd line, useful anti-pruritic

Schedule: II

Directions for use
Apply to ENTIRE body from neck
down including fingernails, waist
and genitalia (entire head and
neck in infants and young
children)
Repeat in 24 hrs
Wash off after 48 hrs

Side effects: local irritation

Precautions/Contra: Not recommended in patients with exudative or vesicular dermatitis, resistance reported

35
Q

Scabies - Sulfur 5-10%

Which line of treatment?
Schedule
Precautions
Contraindication
Directions for use
Side effects
A

2nd line, recommended for
children < 2 months

Schedule: I

Directions for use
Apply to all skin areas
QHS x 5-7 days (3 days
in infants)
Wash off in the morning

Side effects: local irritation, dermatitis w/ repeated applications
Precautions/Contra: Allergies to sulfur *strong smell and can stain clothing

36
Q

Scabies transmisson

A
  • close personal contact
  • ALL close family members/contacts should be treated
  • transmission through fomites rare unless they contain a large number of parasites
  • pets don’t transmit
37
Q

Scabies counselling

  • how to clean
  • when can children go back to school
  • what to do for itch, infections
A
  • trim nails to avoid mites under
  • wash bedding/clothing/toys
  • hot water and dry for 20 mins, dry clean, store in plastic bag for 5-7 days
  • vacuum all surfaces, rugs, furniture, unwashable items
  • antihistamines, topical corticosteroids, cortamition for intense itch
  • topical/systemic antibiotics
  • children may return after 1st treatment
38
Q

scabies treatment failure common causes

A
  • itch may continue up to 4 weeks

common causes of failure
- improper application, re-infestation due to contact, resistance to scabicides, misdiagnossi

  • retreat with scabicides or oral ivermectin
39
Q

scabies - preg/lact

A

permetrin 5% drug of choice - limited data, minimal absorption

crotamiton 10% and precipitated sulfur 7% in petrolatum have low toxicitiy, less effective than permetrhin

40
Q

scabies - monitoring

A

monitor daily for burrows and papules
monitor for itch - resolve in up to 4 weeks
monitor for infection

41
Q

You can get lice and scabies from your pet (T/F)

A

false

Human form of parasites

42
Q

Cutting a person`s hair will prevent lice infestations

A

false (unless shave your hair)

43
Q

Lice can jump or fly

A

false

Crawling or blowing them off hair

44
Q

Lice and scabies always cause itchiness

A

False - delayed hypersensitivity reaction

45
Q

Once you get infested, you can`t get it again

A

false

Treatment failure occurs

Pharmacotherapy (14 decks)

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