7 - Lice & Scabies Flashcards
What are 3 species of lice that exist?
1) Head lice
2) Body lice
3) Pubic lice
Where do the different species of lice live?
- Head and pubic lice live on the skin
- Body lice live in seams of clothing (only come onto body to feed)
What is the shape of head louse compared to pubic louse?
Pubic louse are more round and fat b/c pubic hair is thicker than head hair, so it needs to be round to move up the hair
How long can adult lice survive off of a host?
1-4 days
How long do female louse live and when do they lay eggs?
- Live about 30 days
- Lay eggs daily which hatch 8-10 days later
Where do the different species of lice lay their eggs?
- Head and pubic lice lay eggs at base of hair shafts
- Body lice lay eggs in clothing
How long do the different species of lice take to mature?
- Head and body = 8-15 days
- Pubic = 14-22 days
What are risk factors for head lice?
- Ages 3-11
- Female (tend to have longer hair)
- Lice may prefer clean hair
What are risk factors for body lice?
- Has correlation w/ personal hygiene and socioeconomic status
- Poverty, overcrowding
What are risk factors for pubic lice?
- Sexually active
- Young adults
How is head lice transmitted?
- Hair-to-hair contact
- Fomites such as clothing or hair accessories
How is pubic lice transmitted?
- Sexual or close body contact
- Fomites such as bed linens and towels
How is body lice transmitted?
- Shared clothing or linens
- Direct body contact w/ infested person
What are signs and symptoms of head lice?
- Itching, especially back and side of scalp
- Some will be asymptomatic
- Bite sites (red lesions/papules)
- Presence of lice and nites
When does itching occur from head lice?
- When individual becomes sensitized to saliva from louse feeding
- May take 4-6 weeks during first infestation
Nits are located w/in __ mm of scalp
6
What are signs and symptoms of body lice?
- Nocturnal pruritus
- Bite marks around waist and axillae
- Potential secondary bacterial infection
- Lice and eggs in seams of clothing
What are signs and symptoms of pubic lice?
- Pruritus
- Bite marks (bluish discolouration around bite marks from anti-coagulant that lice inject when they feed)
- Risk of secondary bacterial infection
- Can also occur in other thick-haired areas like beard or eyelashes
- Lice may appear as small, yellow-brown or grey dots
What is required for a definitive diagnosis of head lice?
Visualization of live louse; best way is w/ wet combing technique
What is the wet combing technique?
- Wash hair and apply conditioner (leaving it in hair)
- Brush hair w/ normal brush to remove tangles
- Comb through hair w/ lice comb starting w/ comb flat against scalp and comb to edge of hair
- If there are head lice, 1 or more will appear on comb; if unsure, observe for movement on paper towel
What are some differential diagnoses for head lice?
- Dandruff (flakes of dandruff will be easily removed)
- Seborrheic dermatitis (will present yellowish greasy scales)
- Accumulation of hair cosmetics
- Pseudo-nits (accumulation of dead skin cells that form around hair shaft causing white dead skin cells at hair shaft, easily removed)
- Psychogenic itch
What are some differential diagnoses for pubic lice?
- Seborrheic dermatitis
- Folliculitis
- Dermatophytosis (jock itch)
What are some differential diagnoses for body lice?
- Seborrheic dermatitis
- Folliculitis (will appear infected)
- Eczema/atopic dermatitis (look at location and history
- Impetigo
- Flea or insect bites (location differentiates lice from bed bugs)
What are the goals of therapy for lice?
- Exterminate head, body, or pubic lice
- Relieve pruritus
- Prevent secondary bacterial infections
- Prevent spread of infestation
What is the pathophysiology of scabies?
- Highly contagious infestation of skin w/ human mite Sarcoptes scabiei var hominis
- Impregnated female mite burrows into uppermost layer of epidermis, depositing feces along its path, and lays eggs daily
- Remains in burrow and continues to lay eggs for her lifespan of 4-6 weeks
- Eggs hatch in 3-4 days and maturation into an adult mite takes 14-17 days
What are risk factors for scabies?
- Children, mothers of young children, sexually active adults, and elderly in nursing homes at greatest risk
- Epidemics occur in poor living conditions (poverty, poor hygiene, overcrowding) and institutions
How is scabies transmitted?
- Skin-to-skin contact
- Fomites (furniture, towels) is extremely rare unless px has a very high parasite load
What are signs and symptoms of scabies?
- Pruritus (may take 3-4 weeks to appear for first infestation, or 24-48 hours to appear w/ reinfestation)
- Primary lesions (burrows, vesicles, and papules)
- Secondary lesions
- Mite eggs and feces on skin scraping
- Common on waist, armpits, webbings of fingers, back of elbows, knees, and feet; also genitalia and nipples (not common on heads of adults)
What is a diagnostic tool for scabies?
Skin scraping
What are some differential diagnoses for scabies?
- Seborrheic dermatitis
- Impetigo
- Body lice
- Bed bugs/insect bites
- Eczema (atopic dermatitis)
What are the goals of therapy for scabies?
- Exterminate scabies mite
- Relieve pruritus
- Prevent secondary bacterial infections
- Prevent spread of infestation
Which types of lice are self-treatable?
Head and body
Which conditions should be referred?
Pubic lice and scabies
What are immediate red flags?
- Presence of secondary bacterial infection
- Resistant/recurrent cases where self-care options are no longer viable
- Suspected scabies or pubic lice
- Lice infestation of eyebrows/eyelashes
What are some non-pharms and prevention of lice?
- Remove nits
- Avoid sharing personal items
- Items should be dry cleaned, washed in hot water, or stored in plastic bag for 10-14 days
- Soak combs and brushes in hot water for 5-10 mins or wash w/ pediculicide
- Vacuum carpets, rugs, and furniture
- Inspect close contacts for lice and treat all infested contacts at same time to prevent reinfestation
- Treat bedmates prophylactically
Define pediculicide
Ability to kill lice
Define ovicidal
Ability to kill viable eggs
Define residual activity
Products ability for retention of pediculicide on the hair and scalp after washing
What are some non-Rx treatment options for head lice? Which has residual activity?
- Permethrin (first line tx; has residual activity)
- Pyrethrin/piperonyl butoxide (second line)
- Isopropyl myristate (3rd line)
- Dimeticone (3rd line)
- 5% benzyl alcohol lotion
What are contraindications to permethrin and PPB?
Allergy to ragweed or chrysanthemum
When is dimeticone a good option?
Curly hair
What are possible mechanisms of pediculicide resistance?
- Knockdown resistance (Na channel gene mutation)
- Enzyme upregulation
What should be considered when head lice tx fails?
- Misdiagnosis
- Improper application
- Re-infestation
- Resistance
What should be done when head lice tx fails and it was properly applied?
Switch to a product in a different pharmacologic class
What is the dosing for 5% benzyl alcohol lotion?
- Apply to dry hair for 10 mins then rinse
- 2nd tx needed after 9 days
What is the most common alternative tx for head lice when standard tx fails?
Permethrin 5% left on hair overnight covered w/ plastic shower cap
What is the drug of choice in pregnant and lactating women w/ head lice?
Permethrin, PPB is 2nd choice
Which drugs can be used in children under 2 months old w/ head lice?
Permethrin and PPB
Isopropyl myristate can be used in children over __ years old
4
Dimeticone can be used in children over ___ years old
2
What is the first line tx for pubic lice?
- Permethrin 1% cream rinse
- Pyrethrin w/ piperonyl butozide applied to affected areas then washed off after 10 mins
- 2nd tx in 7-9 days
- Treat sexual contacts from the past month
What is the tx for lice in eyelashes?
- Remove lice and nits w/ tweezers
- Apply white petrolatum BID for 10 days
What is the tx of choice for body lice?
Hygenic measures (pediculicides only used if lice are adherent to body hairs)
What is the monitoring for lice?
Monitor detection of live lice, presence of nits, pruritus, and inflammatory pustules daily for 2 weeks
What must be done before initiating scabies tx?
Diagnosis by physician
Who should be treated for scabies?
Infested person and their close contacts (sexual and household) from the previous month
What are some non-pharms and prevention of scabies?
- Wash clothing and linens in hot water w/ soap and then through hot cycle of dryer
- Store unwashed clothing in plastic bag for 5-7 days
- Vacuum rugs, furniture, and unwashable items
- Avoid body contact w/ others until tx complete
What is the pharm tx of scabies?
- 1st line = permethrin 5% (cream or lotion) for adults and children over 2 months
- 2nd line = crotamiton 10% or topical sulfur 5-10% (preferred tx in infants under 2 months)
How much permethrin 5% should be applied?
- 12 y/o and over = 30 g tube
- 5-12 y/o = 15 g
- 2-5 y/o = 7.5 g
- Under 2 y/o = 4-7 g
- *May require more if px is obese of if scalp is involved
How is permethrin 5% applied?
- Apply to clean, cool, dry skin
- Massage cream into skin from neck to soles of feet and put on clean clothes (note crevices, fingers, toes, nails, and genitalia)
- Remove after 8-14 hours by taking a shower/bath and dress in clean clothes
- Reapply 7 days later if necessary
What is the monitoring for scabies?
- Monitor burrows, papules, pruritus, and pustules/impetigo daily for 2 weeks
How long can transmission of scabies occur?
As long as infested person remains untreated and until 24 hours after tx
What should be done if new burrows appear?
Re-treat w/ scabicide
What should be done if new papules appear?
Re-treat w/ scabicide after 7-10 days
