Infestations Flashcards
What are headlice? (lifecycle? what is? how get?)
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
What are scabies?
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
Where can scabies typically be found?
elbows, fingers, wrists
axilla
extensors of elbows
penis, areola of nipple
What are crusted scabies?
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
What are some sx and signs of head lice?
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
What are the sx and signs of scabies?
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
What are some differential diagnoses for head lice? (explain if possible)
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
What are some differential diagnoses for scabies? (explain if possible)
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
List the main medications used to treat lice (age limit for use)
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
How is malathion used to treat head lice (use instruction)
Applied to dry hair
0.05% = leave for 12 hours
1% = leave for 30 mins
How is pyrethrins + piperonyl butoxide used to treat head lice? (use instructions)
Applies and left for 10 mins
Spray = apply to dry hair
Foam = apply to damp hair
How is isopropyl myristate used to treat head lice? (use instruction, MOA)
Apply to dry hair, leave for 10 mins
coats lice, disrupt water homeostasis and death
How is dimeticone used to treat head lice (use instruction, MOA)
apply to dry hair, leave for 8 hrs
coats lice, disrupt water homeostasis and death
How is benzyl alcohol used to treat head lice (use instruction, MOA)
apply to dry hair, leave for 10 mins
Suffocate lice
Is lice treatment repeated?
Yes, repeat after 7days
What are the steps of the wet combing method?
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
What vulnerable populations is wet combing useful in?
Preg/BF
Babies
People w/ allergies
Asthma
open scalp wounds
How is resistant head lice treated?
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
Why may the lice treatment not be working?
Not using enough product to cover scalp and hair
Not repeating after 7-10 days
Getting reinfested due to head to head contact
List the drugs used to treat scabies
Benzyl benzoate
Topical crotamiton
Sedating antihistamines
Ivermectin = resistant scabies
Permethrin
Crotamiton
What are some key points about the use of permethrin in scabies treatment?
(dose freq, how to apply, what to avoid, how long tx)
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
What are some key points about the use of benzylbenzoate in scabies treatment?
(dose freq, how to apply, what to avoid, how long tx)
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
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)
May help with itch, do not wash off
less effective, causes irritation
apply for 2-5 days
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)
associated w/ itch, can last up to 2-3 wks
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)
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
How can moderately potent corticosteroid be used in scabies?
Can be used after effective course of anti-scabies tx –> relieves itch that can take 3+ wks to resolve
When should you refer for head lice?
Signs of secondary infection
treatment has failed
unclear diagnosis
When should you refer for scabies?
Signs of severe infection
Situated in endemic area
Treatment failed
unclear diagnosis
What lifestyle changes can help with head lice?
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
What lifestyles changes can help with scabies?
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
