Lice & Scabies Flashcards
What is the pathophys of Lice?
Lice are tiny, blood-sucking insects that are specific parasites of humans. Outbreaks in institutions such as schools and long-term care facilities are common, with an estimated prevalence of head lice of 1–3% in elementary school-aged children.
Table 1
What are the risk factors of Head Lice?
- Most common in school-aged children
- Hair length? Hygiene? Ethnicity? (doesn’t affect)
What are the risk factors of Pubic Lice?
- Sexually active
What are the risk factors of Body Lice?
- Poor hygiene
- Poverty
- Overcrowding
What is the transmission of Head Lice?
- Direct head-to-head contact
- Fomites (uncommon): hats, hair accessories, brushes
What is the transmission of Pubic Lice?
- Sexual or close body contact
- Shared clothing & bedding (uncommon)
What is the transmission of Body Lice?
- Shared clothing & bedding
What are the Head Lice Sx’s?
Pruritis
What is the diagnosis of Lice?
- Diagnosis requires detection of a live louse
- Nits are not diagnostic.
- For head lice - Most reliable method of detection is “wet combing”
What is the Wet Combing Technique?
Best way to detect lice infestation, effective for mechanical removal of lice/nits
1. Apply plenty of conditioner from scalp to ends of hair (leaving it in hair)
2. Comb hair with a regular comb to remove tangles
3. Switch to a lice comb. Comb through hair starting with comb flat against the skin of the
scalp and comb to the ends of the hair. (It may help to separate the hair into sections
with clips)
4. After each comb, wipe the comb teeth with piece of paper towel
5. Check the paper towel for lice and eggs (good light will help)
6. Do this until the whole head has been combed through
7. Rinse out conditioner
NOTE:
* If there are head lice you will find 1 or more lice on the comb – if you are unsure, observe for
movement on paper towel
* It takes 20-30 minutes to thoroughly check a head for lice
What are the signs & sx’s of Body Lice?
- Pruritus (often nocturnal)
- Bite marks (waist and axillae)
- Excoriations
- Potential secondary bacterial infection
- *Lice & nits in seams of clothing
Which lice type has disease transmission?
BODY Lice is the ONLY type of lice that CAN SPREAD DISEASE
Trench fever –> can lead to cardiac issues (SOB, chest pain etc.)
What are the signs & sx’s of Pubic Lice?
- Pruritus
- Papules, maculae ceruleae
- Excoriations
- Brown flecks or red spots on skin or undergarments
- Presence of lice & nits
- Location: pubic area, other areas of coarse hair
- Risk of secondary bacterial infection
What is the differential diagnosis of Head Lice?
- Dandruff
- Seborrheic dermatitis
- Accumulation of hair cosmetics
- Pseudo-nits
- Psychogenic itch
What is the differential diagnosis of Pubic Lice?
- Seborrheic dermatitis
- Folliculitis
- Dermatophytosis (jock itch)
What is the differential diagnosis of Body Lice?
- Seborrheic dermatitis
- Folliculitis
- Atopic Dermatitis
- Impetigo
- Flea or insect bites
- Scabies
What is Scabies?
- Highly contagious infestation of the skin by Sarcoptes scabiei
- Epidemics occur in crowded living conditions & institutions
- Most common in children & elderly
Table 3
What is Scabies transmission?
- Prolonged skin to skin contact
- Fomites? (v. rare)
What are the signs & sx’s of Scabies?
- Intense pruritus (worse at night)
- Primary lesions (burrows, vesicles & papules)
- Secondary lesions
- Mite eggs & feces on skin scraping (REQUIRED FOR DIAGNOSIS)
When do Scabies sx’s develop?
?
What is the differential diagnosis for Scabies?
- Seborrheic dermatitis
- Eczema (Atopic Dermatitis)
- Impetigo
- Body lice
- Bed bugs/insect bites
Is Lice a self-treatable condition?
- Can be treated without consulting a doctor
- Encourage physician visit for those with pubic lice
Is Scabies a self-treatable condition?
- Patients without a confirmed diagnosis or exposure to known scabies case should be referred for diagnosis.
What are the red flags for Scabies?
- Presence of secondary bacterial infection
- Resistant/Recurrent cases where self-care options are no longer
viable - Diagnostic uncertainty
What are the topical pharmacological tx’s used for?
Premetrin (1% & 5%) –> head/pubic lice (1%), scabies (5%)
PPB - Head & Pubic Lice, (Scabies - off label)
Isopropyl myristate 50% - Head Lice
Dimeticone 100 cSt 50% - Head Lice
What is Pyrethrin/Permethrin Resistance?
- RESISTANCE PATTERNS ARE HIGHLY VARIABLE FROM COMMUNITY TO COMMUNITY
- Possible mechanisms of resistance to neurotoxins:
- Kdr (knockdown resistance): mutation in sodium channel gene that decreases
neuronal sensitivity to these agents - Increased levels of degenerating enzymes (glutathione S-transferase &
monoxygenase)
Canadian Pediatric Society recommends other reasons for treatment failures should be explored before considering resistance
What are the CI’s of each of the products?
Permethrin - allergy: Ragweed or chrysanthemum???
PBP - allergy: Ragweed or chrysanthemum
Isopropyl Myristate - allergy to ingredients, caution: open flames
Dimeticone - allergy to ingredients, caution: open flames
What are the SE’s of each product?
Permethrin - itching, burning, stinging, redness
PBP - itching, burning, contact dermatitis
Isopropyl Myristate - local irritation & redness, avoid contact with eyes
Dimeticone - local irritation/itching, ocular irritation
Which product does NOT have systemic absorption?
Dimeticone
What are the drugs of choice in Pregnancy/Lactation?
Permethrin
Pyrethrins w/ PB
What are the Ped’s safety for Permethrin?
≥ 2 yrs (product label)
≥ 2 months (guidelines)
What are the Ped’s safety for Pyrethrins w/ PB?
≥ 2 yrs (product label)
≥ 2 months (guidelines)
What are the Ped’s safety for Isopropyl myristate?
≥ 2 yrs (product label)
≥ 4 yrs (guidelines)
What are the Ped’s safety for Dimeticone?
≥ 2 yrs (product label & guidelines)
What is the Lice Tx?
Diagnosis of lice –> Assess & screen close contacts –> Select appropriate tx –> Non-pharms (mechanical removal of nits/lice, treat personal items/environment) –> Retreat in 7-10 days
Who should be treated for Lice?
- Close contacts should be inspected for lice and all infested contacts should be treated at same time to prevent re-infestation.
- BEDMATES SHOULD BE TREATED
- No child should miss school because of lice
What is the non-pharm management for Lice?
- Nit & lice removal with nit comb
- ↓ diagnostic confusion
- ↓ possibility unnecessary re-treatment
- ↓ risk of re-infestation
- Avoid sharing personal items that are in contact with infested area
- Items in prolonged contact with head in the last 2 days should be
washed: - Dry cleaned
- Washed in hot water and dry on hottest dryer setting
- Stored in sealed plastic bag for 10-14 days
- Soak combs and brushes in hot water for 10 mins
- Vacuum furniture???
How do you choose a pharmacological agent?
Choice of product depends on:
* Product efficacy
- Local resistance patterns
- Previous treatment
* Ease of administration
* Safety considerations / patient characteristics (red flags, allergies, age,
contraindications, etc.)
* Cost
* Patient preference
* Consider product efficacy
When do you repeat for the 4 pharmacological tx’s?
repeat in 9 days (7-10 days)
Choosing an agent: Directions for use are KEY for successful treatment:
Educate on proper application technique
Educate on nitpicking/wet-combing
ALL products require a second treatment at about 9 days (7-10 days acceptable)
What are the safety considerations for choosing a pharmacological agent?
Allergies?
Age?
Pregnancy or Lactation?
Is cost a concern?
Is ease of use a concern?
Preference for a specific/type of product
Head Lice Treatment Failures:
- Consider:
- Misdiagnosis
- Improper application: incorrect technique, insufficient amount, second application not given OR inappropriate interval
- Re-infestation
- Resistance
- When PROPERLY applied treatment fails switch to a product in a different pharmacologic class (insecticide vs non-insecticide)
- Treatment failure after adequate trails from AT LEAST two different pharmacological classes should be referred
Possible Alternative therapies when standard therapy fails:
- Oral Ivermectin (off-label): 200mcg/kg, two doses given 7-10 days apart (Cost: ~$150)
CAUTION in children less than 15 kg (theoretical risk of neurotoxicity) Likely safe in pregnancy and lactation (minimal studies) - Topical Ivermectin (off-label): 1% cream applied to dry hair & rinsed after 10 minutes (Cost ~$200)
- Permethrin 5% left on hair overnight covered with plastic shower cap
What are the OTHER Head Lice Tx’s?
Manual removal only (“nit busting”)
- Manual removal should always be used in conjunction with all head lice treatment
- Wet-combing every 2-3 days for at least 3 weeks. Tedious and time consuming but may be effective
- Electronic combs – lack evidence, avoid in those with pacemakers or seizure disorders
Occlusive agents (petrolatum, Cetaphil cleanser, mayonnaise, olive oil)
- May slow movement and facilitate easier removal with nit comb.
- Need to combine with manual removal
- Treatment remains on for 8 hours, retreat weekly x 3 weeks
- Limited evidence
What are methods to avoid?
- Treatments including trimethoprim/sulfamethoxazole
- Lack of evidence
- Antibiotic stewardship/antibiotic resistance
- Furniture & Household sprays
- May contain permethrin or pyrethrins.
- Essential oils (ylang ylang, Andiroba, tea tree, lavender, rosemary, combinations, citronella, lemon grass, star anise)
- Evidence does not support use
- Potential for adverse effects: local irritation, inflammation, allergic contact eczema or
dermatitis - Watch out for product extensions!!!
- Nix® product extensions: star anise oil, dimethicone with inappropriate directions for use, mineral oil
What is the Tx of Pubic Lice?
- Permethrin 1% or PPB are treatments of choice
- Apply to affected areas, wash off after 10 min.
- Second treatment in 9 days
- Education: lice & nit removal, avoid sexual contact until infestation is clear, *refer for STI screening
- Sexual contacts within the previous month should informed and treated if infested
- Eyelash involvement:
- Apply ocular grade white petrolatum twice daily for 10 days (Systane Ointment® or Soothe DuoLube®)
What is the Tx of Body Lice?
- Pharmacological agents unnecessary
- Hygienic measures treatment of choice:
- Bathing
- Hot laundering of clothing & linens
- Seal items in plastic bags x 10-14 days
- Consider referral to social services to assess improving living conditions
- If patients have numerous body lice that are adherent to body hairs treatment with permethrin 5% (applied for 8 to 10 hours to entire body) may be considered.
What is the monitoring therapy for Lice?
Frequency: daily to every 3 days
Lice & Nits: decreased or none after 1st tx, none after 2nd tx
Lesions: normal skin appearance within 1 week, signs of infection
Pruritis: decreased over 1-3 weeks
What is the Scabies tx?
- Definitive diagnosis should be ensured prior to treatment
- Infestation of the patient or a close contact should be confirmed
- Infested persons, household members AND sexual partners from the previous month should be treated at the same time
What are the Non-Pharmacological Treatment & Prevention of Scabies?
- Wash clothing, bedding and towels from the last 3 days in hot water and dry in hot dryer (or dryclean)
- Store unwashed items in plastic bags for 7 days.
- Vacuum rugs & furniture
- Trim fingernails
- Avoid body contact with others until treatment complete
What are the Topical Treatment of Scabies?
- Permethrin 5%
- Most effective, recommended treatment for adults and children >2 months
- Available in cream or lotion formulations (Nix® cream , Kwellada-P ® Lotion)
- Second line options include:
- Topical sulfur 5 to 10%
- Prevents respiration in insects
- Limited data demonstrating efficacy
- Preferred treatment in infants <2 months
- Crotamiton 10%
- Less effective than permethrin and resistance reported
What are the Severe Scabies?
Resistant Scabies, Crusted Scabies, Institutional Outbreaks
Resistant Scabies:
- Oral ivermectin 200 mcg/kg as a single dose
- Repeat in 2 weeks
Crusted Scabies:
- Oral ivermectin 200 mcg/kg as a single dose on days 1, 2, 8, 9 & 15
- AND topical permethrin 5% full body application daily x 7 days
Institutional Outbreaks:
- Topical treatment of everyone with permethrin 5% if feasible
- Alternative: treat all with oral ivermectin 200mcg/kg, repeat in 7-14 days.
Application of Permethrin 5%:
- Apply to clean, cool, dry skin
- Massage cream into skin from neck to soles of feet (pay attention to crevices: fingers, toes, nails, armpits, genitalia). Put on clean clothes.
- If hands are washed – reapply.
- Remove after 8 to 14 hours by showering. Dress in clean clothes.
- Reapply 7 days later only if necessary (live mites, new lesions)
Infants: Apply to scalp, forehead & temples. Recommend long sleeved clothing and mittens to prevent ingestion.
Treatment of Scabies:
Nix (Permethrin 5%) Dosing (30 gram tube):
* Adults & children > 12 years: 30 g tube
* Children 5-12 years: 1⁄2 tube (15 g)
* Children 2-5 years: 1⁄4 tube (7.5 g)
* <2 years: 1/8-1/4 tube (4-7g)
* Patients who are obese may require more than 30g
Scabies Monitoring:
table 4
