Lice and Scabies Flashcards
(40 cards)
What is the impact of lice?
1) causes concern and stress among infected individuals - lowers QOL
2) social stigma surrounding infestation
3) significant amount of absenteeism from work and school
How many lice are typical for a lice infestation and how long will they live without treatment?
<20 mature head lice
Will live 3 to 4 weeks if left untreated, feeding every 3-4 hours
How is head lice transmitted?
Head to head contact
How long can lice live?
21-27 days, the females can lay ~4 eggs per day
Away from the host, the head lice will die within 1-2 days
How does itching develop in individuals infested with lice?
Itching occurs if the host becomes sensitized to antigenic components in the saliva injected as the louse feeds
* some people remain asymptomatic
How do you diagnose an active lice infestation?
Find one live louse
Nits do not mean that there is an active infestation, especially if they are further than 6mm away from the scalp
How do you perform an inspection of air to find nits?
Comb wet hair systemically with small parts at a time, saturated with white conditioner to make it harder for lice to move quickly out of view
NEED A LICE COMB with spiral groove to dislodge nits
Contents of the comb and materials need to be examined and removed after EACH brush through
When should you refer a patient presenting with lice? (3)
1) Patient/caregiver has not seen a live louse or viable nit infestation (itching without being able to find anything is a problem)
2) Patient has had multiple treatment failures –> could indicate resistant strain
3) Presents with a secondary infection
What are the goals of therapy for treating a lice infestation?
1) exterminate lice
2) relieve pruritus
3) Prevent secondary bacterial infections
4) prevent the spread of the infestation
What are the non-pharmacological management options for the treatment of lice?
DISCLAIMER: non-pharmacological options are generally only recommended adjunctively
- environmental cleaning is generally not warranted
- avoid sharing personal items
- identify and examine the potential contacts
- mechanical removal via wet combing (every 3-4 days for 2 weeks)
- AirAlle/LouseBuster –> limited evidence points to efficacy but we cannot really recommend according to that
What is the gold standard pharmacological treatment for lice infestations? List the brand, age appropriateness, general application, AEs and cure rate.
Permetherin 1% cream –> brand: Kwellada-P, Nix
As per Canadian clinical standards, safe for use in >2 months
Application instructions:
- wash hair with conditioner free shampoo
- rinse with water and towel dry hair
- apply ~25-50mL to saturate hair and scalp
- leave on for 10 minutes
- rinse hair thoroughly with cool water and towel dry
- repeat in 7 days
AE: mild transient itching, redness, burning sensation of scalp, avoid in patient with chrysanthemum allergy
Safe in pregnancy
96-100% cure rate
What is the other topical insecticide used for lice infestations? List the brand, age appropriateness, general application, AEs and cure rate.
Pyrethrins 0.33%, Piperonyl butoxide 3.0% shampoo –> R&C Pronto
As per Canadian clinical standard guidelines, safe for >2 months
Instructions:
- apply to dry hair
- saturate hair and massage scalp/skin with >25mL of product
- leave for 10 minutes
- add water and lather and work into hair
- rinse with cool water and towel dry
- repeat treatment in 7 to 10 days
AEs: itchy or mild burning scalp, avoid in patients with allergy to ragweed and chrysanthemums
Safe in pregnancy
45-94% cure rate (first and second treatments respectively)
What is the most important counselling point when recommending a topical insecticide for the management of lice?
Itching after treatment is NOT a symptom of reinfection
If a patient is unsure of using an insecticide because they’re toxic, what should you tell them?
They don’t absorb through the skin and are safe to use
To minimize exposure elsewhere on the body, do not sit a child in the bath to rinse their hair
What are the product selection guidelines for picking a topical insecticide?
- preferred dosage form
- past medication experiences
- patient allergies and sensitivities
- convenience or desire for a single application
List the brand, age appropriateness, general application, AEs and cure rate for Dimeticone solution.
Dimeticone 50% is a non-insecticide –> Brand: Nyda
Can be safely used in >2 years of age
Instructions:
- saturate dry hair with spray and massage/comb into the hair
- after 30 minutes, comb with lice comb to remove dead lice and nits
- allow solution to dry on hair and for at least 8 hours
- wash out with regular shampoo
- repeat treatment in 8-10 days
AEs: less safety data than 1st line agents but no toxicity or resistance to date
97% effective; 100% ovoidal after 2 treatments
What is the MOA for Dimeticone/Nyda?
Solution flows into breathing systems of lice and nits, then thickens and suffocates them
List the brand, age appropriateness, general application, AEs and cure rate for Isopropyl myristate/cyclomethic one solution.
Brand: Resultz rinse
Clinical practice guidelines say safe in >4 years, package says >2 years
Instructions:
- saturate dry hair and scalp with product
- massage into scalp and leave for 10 minutes
- rinse with warm water
- repeat treatment in 7-10 days to kill new eggs
AEs: can stain clothing, less safety info than 1st line agents
57-93% effective after first and second application - NOT ovicidal
List the brand, age appropriateness, general application, AEs and cure rate for benzyl alcohol 5% lotion.
Brand: Ulesfia (most expensive option)
Safe for 6 months old to 60 years
Instructions:
- apply appropriate amount to dry hair and leave for 10 minutes
- rinse with water
- shampoo hair immediately
- remove dead lice with lice comb
- repeat in 7-9 days
AEs: expensive, well tolerated but may cause skin irritation, eye irritation, numbness, and decreased sensitivity, use in neonates has been associated with neonatal gasping syndrome
No effectiveness percentage given although it has no effect on nits
What are the treatment options to avoid for lice?
White vinegar –> may interfere with the efficacy of permethrin
Essential oils –> not supported for use in infants and children
Other NHPs –> no clinical evidence
Flammable liquids –> ineffective and may cause harm
What are the reasons that lice treatment may fail?
- misdiagnosis
- improper use of pedicullicide (not following instructions or repeating treatment)
- inadequate manual removal (needed in conjunction with pharmacologic treatment)
- repeated exposure/reinfestation
- resistance to pediculicide (rare)
What are some alternative Rx therapies for head lice?
Trimethoprim/topical permethrin 1% –> not approved in Canada for use against head lice (IMPORTANT: avoid in pregnancy)
Ivermectin –> 2 single doses 200ug/kg 7-10 days apart, not safe for under 15kg children
Ivermectin 0.5% –> not approved in Canada yet, similar efficacy to oral dosage
Permethrin 5% –> larger adverse effect profile, more itching after application
What are the treatments for pubic lice?
Same as head lice –> permethrin 1% or pyrethrins with piperonyl butoxide
If eyelashes are infested: remove nits with lice and tweezers, apply an occlusive non-medicated eye ointment like Lacralube
Sexual contacts within the previous month should be treated
Itching caused by the pediculocide can be treated with oral antihistamines or low-potency topical corticosteroid
What is the treatment for body lice?
Pediculicides are unnecessary, 1st line is simple hygienic measures:
- bathing and laundering if infested clothing and linens in hot water
- dry cleaning or storing the items in a sealed plastic bag for 2 weeks
If the lice are adherent to body hairs, pediculicides may be helpful
