Lice and Scabies Flashcards
(45 cards)
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
