Lice & Scabies

Question 1

What is pediculosis

Answer 1

head lice, body lice, and pubic lice

Question 2

what is head and body lice caused by

Answer 2

pediculus species

Question 3

what is pubic lice caused by

Answer 3

phthisis (crab louse)

Question 4

what is the life cycle of lice

Answer 4

• female lays eggs (nits) on the hair
• eggs hatch after 10 days releasing nymphs
• nymphs mature in 2 weeks
• live by sucking the blood of the host

Question 5

How is lice transmitted

Answer 5

• close contact

- associated with poor hygiene

Question 6

how many cm/day does head lice crawl up to

Answer 6

23 cm/day

Question 7

how many mm/day does scabies burrow

Answer 7

2-3 mm/day

Question 8

How are head and pubic lice diagnosed

Answer 8

by finding lice or nits (eggs) on examination. Excoriations (due to scratching) may also be present

Question 9

How is body lice diagnosed

Answer 9

by pruritus in susceptible individuals, lice typically found on clothes

Question 10

what patient population is head lice most common in

Answer 10

children, transmission occurs from person to person contact and indirectly via such items as hats, clothes, and pillowcases

Question 11

How is body lice transmitted

Answer 11

louse attaches to clothes; infestations occur when clothes are not washed or changed frequently

Question 12

How is pubic lice transmitted

Answer 12

sexual intercourse

Question 13

What is the treatment algorithm for head, pubic, and body lice

Answer 13

1. Lice confirmed by presence of lice or eggs
2. non - pharm treatments
3. 1st line: permethrin 1% or other pyrethrin combination
   - if treatment failure: Malathion or benzoyl alcohol OR other available pyrethrin combination
4. If treatment failure with either medication: treat with Ivermectin, Spinosad, or TMP/SMZ to topical therapy

Question 14

what is scabies caused by

Answer 14

Sacroptes scabei aka “itch mite”

Question 15

What are the common sites scabies infect

Answer 15

• genitals
• feet
• hands/fingers
• buttocks
• knees
• armpits
• stomach

Question 16

how long does mites live

Answer 16

3-7 days away from host

Question 17

Hoe does scabies present

Answer 17

thread like burrows, excoriations, between the fingers, wrists, elbows, axillae, may be crusting especially in children.

Question 18

How does crusting scabies present

Answer 18

hyperkeratotic plaques that house thousands of mites

Question 19

what are general treatment strategies of scabies

Answer 19

• two treatments given one week apart to prevent re-infestation and any mites left on skin
• topical treatment is applied to the entire body
• linens and clothing should be washed in warm water and dried on high heat

Question 20

What is the first line therapies for scabies

Answer 20

permethrin 5% cream and Ivermectin oral

Question 21

what is an alternative treatment option for scabies

Answer 21

lindane 1% lotion

Question 22

what are the last tine options for scabies

Answer 22

• crotamiton 10% cream: not very effective

- precipitated sulfur 5-10%: messy, odorous, staining

Question 23

what patient population is ivermectin not recommended for

Answer 23

children under 15 kg or pregnant women

Question 24

What is benzyl alcohol used for

Answer 24

lice

Question 25

what dosage form does benzyl alcohol come in

Answer 25

5% lotion

Question 26

How does benzyl alcohol work

Answer 26

causes asphyxiation by blocking respiratory spiracles

Question 27

which medication for lice is the only non-neurotoxic agent

Answer 27

benzyl alcohol

Question 28

How should benzyl alcohol be administered

Answer 28

apply to dry hair for 10 mins. rinse with water. repeat in seven days. amount is dependent on hair length.

Question 29

what should a patient be warned about when using benzyl alcohol

Answer 29

use caution in children as it may cause gasping syndrome; avoid in infants < 6 months due to increased absorption

Question 30

what are some ADR with benzyl alcohol

Answer 30

pruritus, erythema, eye irritation

Question 31

What is ivermectin used for

Answer 31

lice and scabies

Question 32

what are the dosage forms of ivermectin

Answer 32

- oral tabs (lice and scabies): Rx | - cream rinse (lice): OTC

Question 33

what are the oral tablets of ivermectin indicated for

Answer 33

off label for lice and scabies but is endorsed by the CDC as a treatment option

Question 34

what is the new topical agent of ivermectin called

Answer 34

SKLICE

Question 35

what kind of drug is ivermectin

Answer 35

anti-helminthic agent

Question 36

what should someone that is taking ivermectin be warned about

Answer 36

oral: symptomatic postural hypotension; association between 6 month mortality and ivermectin in long term care residents; should not be used in children < 15 kg or pregnant women

Question 37

What are some ADR associated with ivermectin

Answer 37

oral: peripheral edema, tachycardia, GI SE, transaminase elevations

Question 38

what is lindane used for

Answer 38

lice and scabies

Question 39

what is the dosage form of lindane

Answer 39

shampoo

Question 40

what is the pharmacology of lindane

Answer 40

- CNS stimulant that produces seizures and death of mites - takes over 3 hours to kill the lice: during this time patients commonly experience increased pruritus as a result of lice crawling and twitching

Question 41

what should patients taking lindane be warned about

Answer 41

- contraindicated in neonates and warning against use in children < 50 kg - up to 10% of topical applications may be absorbed

Question 42

what are some ADR when using ivermectin

Answer 42

black box warning: neurotoxicity (dizziness to seizures and death) - use caution with other drugs that lower seizure threshold - fertility impairment

Question 43

What is malathion used for

Answer 43

lice

Question 44

what is the dosage form of malathion

Answer 44

0.5% lotion (isopropyl alcohol content is high; flammable)

Question 45

what is the pharmacology of malathion

Answer 45

ovicidal agent with rapid activity and low toxicity despite its being an organophosphate

Question 46

who is malathion contraindicated in

Answer 46

children < 24 months

Question 47

what are some SE with malathion

Answer 47

irritation of scalp and skin

Question 48

what is permethrin used for

Answer 48

lice and scabies (most commonly used)

Question 49

what is the pharmacology of permethrin

Answer 49

- acts on neural cell membranes- delaying repolarization and leading to paralysis - possesses ovicidal activity - 26 times less toxic than lindane - 3 times less toxic than pyrethrins

Question 50

what should patients taking permethrin be warned about

Answer 50

- may cause worsening of asthma or exacerbation | - photosensitivity

Question 51

what are some SE associated with permethrin

Answer 51

pruritis, erythema, rash of the scalp (or applications site), burning, stinging, tingling

Question 52

what is pyrethrins used for

Answer 52

lice

Question 53

what is the dosage form of pyrethrins

Answer 53

topical cream rinse (OTC)

Question 54

what is the pharmacology of pyrethrins

Answer 54

- derived from chrysanthemums (avoid if patient has rag weed allergy) - interferes with louse neural transmission - paralysis and death - piperonyl butoxide - augments the activity of pyrethrins by inhibiting the hydrolytic arthropod enzyme responsible for pyrethrin metabolism

Question 55

what are some SE associated with pyrethrins

Answer 55

- persons with allergy to ragweed, chrysanthemums, or other pyrethrin products - should not be used near the eyes or on mucous membranes

Question 56

what is Spinosad used for

Answer 56

- head lice in adults and children > 4 years | - off label can be used in children > 6 months

Question 57

what is the dosage form of Spinosad

Answer 57

topical suspension 0.9%

Question 58

what is the pharmacology of Spinosad

Answer 58

CNS stimulant that produces louse neuronal excitation, paralysis, and death

Question 59

what are some SE associated with Spinosad

Answer 59

local: application site erythema; skin irritation | - ocular erythema

Question 60

What is the benefit of adding TMP/SMZ to permethrin

Answer 60

higher success rates than either agent alone | - add to permethrin only if nits and lice are found 2 weeks after first course of therapy