Lice and Scabies Flashcards
What are the types of lice?
which are vectors of disease
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
signs/symptoms of lice
- 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
where is lice found?
- 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
life cycle of the louse?
- 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
explain wet-combing
- 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
Goals of therapy (4)
- elim lice infestation
- relieve itch
- prevent transmission
- prevent secondary bacterial infection
Name 4 treatment options
- permethrin 1% (Nix, Kwellada-P)
- pyrethrins with piperonyl butoxide (R&C)
- isopropyl myristate 50% w/w cyclomethicone 50% (Resultz)
- dimeticone 50% (NYDA)
Permethrin 1% (Nix, Kwellada-P)
Class Schedule MOA Precautions Contraindication Directions for use Side effects Efficacy Resistance
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)
Pyrethrins with Piperonyl Butoxide (R&C)
Class Schedule MOA Precautions Contraindication Directions for use Side effects Efficacy Resistance
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
Isopropyl myristate 50% w/w
cyclomethicone 50 % (Resultz)
Class Schedule MOA Precautions Contraindication Directions for use Side effects Efficacy Resistance
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)
Dimeticone 50% (Nyda)
Class Schedule MOA Precautions Contraindication Directions for use Side effects Efficacy Resistance
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)
Gamma benze hexachloride (Lindane)
- pediculocid, causes louse paralysis
45-70% ovicidal - possible neurotox and bone marrow suppression
- carcinogenic, removed from market
Benzyl alcohol 5% lotion
- pt >6 mos (safety over 60 not established)
- MOA: stun spiracles open so solution can enter and suffocate louse
- not ovicidal
What are some natural treatments?
evidence?
Tea tree oil” antimicrobial/antiseptic
Mayo/olive oil: suffocate louse
Vaseline/cetaphil cleanser: suffocate louse
all have no evidence
Other non-drug measures for lice?
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
How can lice get transmitted?
- 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
Cleaning procedures
- 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
Counselling pts
- what type of comb?
- when can children return to school?
- 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
what to do if very itchy or secondary infection?
itch -very bothersome and cause injury to skin surface
- antihistamines, topical corticosteroid
secondary infection - lesions caused by itching
- topical antibiotics, may need systemic
what are some reasons of treatment failure?
- non-adherence to instructions
- failutre to retreat or re-application too soon
- poor nit removal technique
- pediculocide resistance
- misdiagnosis
- repeated exposure
Body lice
signs and symptoms
diff diag
how to treat
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
Pubic lice
signs and symptoms
diff diag
how to treat
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
lice in eyelashes
how to treat?
- remove with tweezers
- apply Vaseline BID for 10 days to suffocate
- more data needed for olive oil and mayo
pregnancy and lactation
compatible with permethrin 1% and pyrethrins with piperonyl butoxide
no data for isopropyl myristate cyclomethicone or dimeticone
monitoring
monitor daily for 2 weeks
monitor for itch - can recommend antihistamines or topical corticosteroids
monitor for secondary infections - antibiotics
Scabies - epidemiology
- 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
scabies life sycle
- 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
scabies signs and symptoms
where is it located in body?
- 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
crusted scabies (Norwegian Scabies)
- 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%
diagnosis of scabies
diff diagnosis
- 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
scabies goals of therapy (4)
- exterminate parasites
- relieve itch
- prevent spread of infestation
- prevent secondary bacterial infection
Name 3 treatment options for scabies
permetrin 5%
crotamition 10% (Eurax)
sulfur 5-10%
Scabies - Permethrin 5% (Nix, Kwellada-P)
Which line of treatment? Schedule Precautions Contraindication Directions for use Side effects
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
Scabies - Crotamiton 10% (Eurax)
Which line of treatment? Schedule Precautions Contraindication Directions for use Side effects
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
Scabies - Sulfur 5-10%
Which line of treatment? Schedule Precautions Contraindication Directions for use Side effects
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
Scabies transmisson
- 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
Scabies counselling
- how to clean
- when can children go back to school
- what to do for itch, infections
- 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
scabies treatment failure common causes
- 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
scabies - preg/lact
permetrin 5% drug of choice - limited data, minimal absorption
crotamiton 10% and precipitated sulfur 7% in petrolatum have low toxicitiy, less effective than permetrhin
scabies - monitoring
monitor daily for burrows and papules
monitor for itch - resolve in up to 4 weeks
monitor for infection
You can get lice and scabies from your pet (T/F)
false
Human form of parasites
Cutting a person`s hair will prevent lice infestations
false (unless shave your hair)
Lice can jump or fly
false
Crawling or blowing them off hair
Lice and scabies always cause itchiness
False - delayed hypersensitivity reaction
Once you get infested, you can`t get it again
false
Treatment failure occurs
