Infestations

Question 1

What are headlice? (lifecycle? what is? how get?)

Answer 1

Live of scalp and lay eggs on hair –> suck blood (nutrients) –> inject spit into scalp –> itch

Acquired by direct head to head contact

Lifecycle = completed on human head, die rapidly if not on head due to dehydration
- eggs= need moisture and warmth to hatch
- lice = need warmth, moisture, food to live and breed

Question 2

What are scabies?

Answer 2

Human pathogen spread by close (skin-skin) contact, not acquired from animals

Invades upper most skin later (stratum corneum) –> mite burrows into particular sites –> females lay eggs (1-3/day) –> extend burrow several mm a day

Found in school ages children, closed communities, indigenous communities

Question 3

Where can scabies typically be found?

Answer 3

elbows, fingers, wrists

axilla

extensors of elbows

penis, areola of nipple

Question 4

What are crusted scabies?

Answer 4

prev known as Norwegian scabies, usually in immunocompromised

Infestation w/ millions (high no.) of mites

Results in thick crusts forming on affected area (feet, scalp)

Misdiagnosed as psoriasis, seborrheic dermatitis

tx= oral ivermectin

Question 5

What are some sx and signs of head lice?

Answer 5

May see eggs (nits) on hair, active lice infestation when you can see live, moving mite

Can be asymptomatic, itching and irritation is from louse feeding. Scratching causes crusting and scaling

Secondary bact –> small sores w/ tender glands in neck

Unhatched eggs = dark area within the shell (close to scalp), hatched eggs are transparent

Dermatitis and occur w/ heavy infestation

Question 6

What are the sx and signs of scabies?

Answer 6

Definitive diagnosis = microscopic I.D. of mites and their eggs from skin scraping at burrows

Sx = itchy, worse at night or after hot shower
- fam hx?
- consider if male w/ widespread itch on trunk, limbs, red papules/nodules on penis and scrotum

Sensitisation = 5 wks

Future infestation = itchy occur soon after transmission

Burrows may be visible
- fine linear rash/ridge across skin
- Most noticeable on inner aspect of wrists, between fingers

papular and erythematous lesion may occur near mite scratching

Question 7

What are some differential diagnoses for head lice? (explain if possible)

Answer 7

Seborrhoeic dermatitis = flaky patch more easily removed from scalp/hair, check other hair bearing areas

Psoriasis = silvery, thick patches, may be hairloss

Atopic dermatitis = looks red and can have weeping lesions

Question 8

What are some differential diagnoses for scabies? (explain if possible)

Answer 8

Insect bites = will induce papular urticaria, can occur anywhere, generally resolve after a few days

Dermatitis = allergic contact (check hx), pompholyx/dyshidrotic eczema (stress related?)
- scabies will be itchier at night

Question 9

List the main medications used to treat lice (age limit for use)

Answer 9

Malathion = children >6 months

Pyrethrins + piperonyl butoxide = all ages

Isopropyl myristate = children >2 yrs

Dimeticone = all ages

Benzyl alcohol = children >6 months

Herbal and essential oils = >6 months

Question 10

How is malathion used to treat head lice (use instruction)

Answer 10

Applied to dry hair

0.05% = leave for 12 hours
1% = leave for 30 mins

Question 11

How is pyrethrins + piperonyl butoxide used to treat head lice? (use instructions)

Answer 11

Applies and left for 10 mins

Spray = apply to dry hair

Foam = apply to damp hair

Question 12

How is isopropyl myristate used to treat head lice? (use instruction, MOA)

Answer 12

Apply to dry hair, leave for 10 mins

coats lice, disrupt water homeostasis and death

Question 13

How is dimeticone used to treat head lice (use instruction, MOA)

Answer 13

apply to dry hair, leave for 8 hrs

coats lice, disrupt water homeostasis and death

Question 14

How is benzyl alcohol used to treat head lice (use instruction, MOA)

Answer 14

apply to dry hair, leave for 10 mins

Suffocate lice

Question 15

Is lice treatment repeated?

Answer 15

Yes, repeat after 7days

Question 16

What are the steps of the wet combing method?

Answer 16

Comb hair conditioner onto dry, brushed (detangled) hair –> lice cant run or grip

Thoroughly comb sections of hair w/ fine tooth lice comb

Wipe conditioner from comb onto paper towel or tissue

Look on tissue and on comb for lice and eggs

repeat combing for every part of head at least four or five times

if lice or eggs are found, person should be treated

Question 17

What vulnerable populations is wet combing useful in?

Answer 17

Preg/BF

Babies

People w/ allergies

Asthma

open scalp wounds

Question 18

How is resistant head lice treated?

Answer 18

Repeat treatment using another insecticide or wet combing

Not listed indication but can be used: ivermectin orally w/ fatty food as single dose repeated in 7 days or specialist referral

Question 19

Why may the lice treatment not be working?

Answer 19

Not using enough product to cover scalp and hair

Not repeating after 7-10 days

Getting reinfested due to head to head contact

Question 20

List the drugs used to treat scabies

Answer 20

Benzyl benzoate

Topical crotamiton

Sedating antihistamines

Ivermectin = resistant scabies

Permethrin

Crotamiton

Question 21

What are some key points about the use of permethrin in scabies treatment?

(dose freq, how to apply, what to avoid, how long tx)

Answer 21

Treatment of choise

Direction = apply from chin down (attention to hands, genitals, under nails) and leave on for 8 hrs min, reapply to areas that are washed

If tx failed, leave on for 24hrs

Repeat after 7 days

Question 22

What are some key points about the use of benzylbenzoate in scabies treatment?

(dose freq, how to apply, what to avoid, how long tx)

Answer 22

More irritating = use test dose, if irritation - dilute for adults and use alternative in children

Direction = apply chin down, wash off 24hrs late, reapply to washed areas

Undiluted application for adults, dilutes (w/ 3 parts water if 2month - 12yrs, equal parts water - 2-12yrs) for children

Repeat after 5-7 days

Question 23

What are some key points about the use of topical crotamiton in scabies treatment?

(dose freq, how to apply, what to avoid, how long tx)

Answer 23

May help with itch, do not wash off

less effective, causes irritation

apply for 2-5 days

Question 24

What are some key points about the use of sedating antihistamines in scabies treatment?

(dose freq, how to apply, what to avoid, how long tx)

Answer 24

associated w/ itch, can last up to 2-3 wks

Question 25

What are some key points about the use of ivermectin in resistant scabies treatment?

(dose freq, how to apply, what to avoid, how long tx)

Answer 25

PBS authority = failed topical tx, or crusted scabies combined w/ topical tx

Dose varies:
- typical scabies = apply days 1, 2, and 8
- severe crusted = more doses e.g. days 9, 15, 22 and 29

Question 26

How can moderately potent corticosteroid be used in scabies?

Answer 26

Can be used after effective course of anti-scabies tx –> relieves itch that can take 3+ wks to resolve

Question 27

When should you refer for head lice?

Answer 27

Signs of secondary infection

treatment has failed

unclear diagnosis

Question 28

When should you refer for scabies?

Answer 28

Signs of severe infection

Situated in endemic area

Treatment failed

unclear diagnosis

Question 29

What lifestyle changes can help with head lice?

Answer 29

Wash pillow cases on hot cycle, combs and brushes in hot water (60 degrees c)

Family and close physical contact –> examined and treated if live lice are found

Patient’s school should be notified, but not necessary to exclude child after initial tx

Question 30

What lifestyles changes can help with scabies?

Answer 30

Underwear, nightclothes, bath towels, bed linen that may have been used in last 3 days should be washed in hot water or dry cleaned

Soft toys, doonas can be exposed to UV light for several hours

Sexual partners, household or institutional contacts should be tx at same time (in closed communities, everyone should be treated)

Follow up 4-6 wks after tx