Lice, scabies, spider bites Flashcards
1
Q
What is pediculosis?
A
- ectoparasites that live on body and feed on human blood after piercing the skin
- pediculosis capitus: head lice
- pediculosis corporis: body lice
- very common
- body and scalp lice are about 1-3 mm long
- unable to jump or fly
2
Q
Clinical presentation of pediculosis?
A
- pruritus: may take 2-6 wks to develop after 1st exposure
- itching and scratching can lead to secondary cellulitus
- pubic lice should prompt eval for other STIs
3
Q
Dx of pediculosis?
A
- observe:
eggs (nits)
nymphs
mature lice - commonly found behind ears and on back of neck
- wood lamp of area: yellow/green fluorescence of lice/nits
4
Q
Meds for pediculosis?
A
focus on 2 mechanisms:
- neurotoxicity - permethin 1% lotion (nix) first line
- suffocation via coating: benzyl alcohol 5% lotion (Ulesfia)
spinosad 0.9% (natroba): promotes hyperexcitiation and death by paralysis
- enviro control: tx all persons who have contact with infested pts (esp partners)
5
Q
What are scabies?
A
- sarcoptes scabiei
- aka seven yr itch
- contagious infection caused by mite Sarcoptes Scabiei
- tiny and usually not directly visible
- parasite that burrows under the host’s skin causing intense itching
6
Q
How are scabies transmitted? When does the pt become sx?
A
- may be transmitted from objects
- most often transmitted by direct skin to skin contact:
higher risk for prolong. contact
nursing homes
extended care facilities
prisons
child care facilities - usually 2-6 wks b/f pt becomes sx
7
Q
3 MC skin disorders in kids?
A
- scabies
- Tinea
- pyoderma
8
Q
Classic scenario of scabies?
A
- itching: caused by allergic rxn to mites made worse by warmth usually worse at noc watch for excoriation - see burrowing - common areas: wrists, axillae, waist, feet, ankles
9
Q
How is scabies dx?
A
- scrape off tiny bit of skin
- view under a microscope for mites or eggs
10
Q
Tx for scabies - 1st line? SEs?
A
- permethrin cream 5% 60 g tube (preferred)
- apply from head to feet
- leave on 8-14 hrs then wash with soap and water
- repeat in 7 days if necessary
- safe for kids as young as month old and pregnancy
- SEs:
mild to mod burning and stinging
itching
rash
redness - tx family members and sexual partners
- wash clothing, bedding, or towels in hot water and dried using hot temp
- can give something for itching:
atarax (hydroxyzine) 10-25 mg po q 4-6 hrs prn itching - steroid cream
- watch out for secondary infections
11
Q
Alt meds for scabies?
A
lindane lotion 1%:
- has more neurotoxicity than permethrin
- apply thin layer of lotion and massage from neck to toes: leave on 8-12 hrs
- most pts reqr 30 ml but larger adults up to 60 ml
oral ivermectin:
- one study found that is more effective than lindane but less effective than permethrin
- 200 mcg/kg by mouth as single dose with repeat dose in 2 weeks
- CDC recommends not using in pregnant or lactating women
12
Q
What spiders are most likely to inflict medically significant bites?
A
- widow
- recluse
- there are a lot of common disorders can mimic a spider bite
- acute presentation: papules, pustules, or wheal (most resolve 7-10 days)
13
Q
What disorders can mimic spider bites?
A
- other insect bites: flea, fly, mite, tick bites
- skin disorders: erythema nodosum, TENs
- infections: chronic herpes simplex, MRSA
14
Q
Where are widow spiders found?
A
- worldwide
- outside - garage, shed, under furniture
- unremarkable local lesions: characteristic systemic rxn
- latrodectus genus
- not all are black
- neurotoxin: alpha-latrotoxin = effects neuromuscular transmission
15
Q
Where are recluse spiders?
A
- found in N and S America
- notorious for becoming necrotic (rare)
- systemic rxn mild: nonspecific signs and sxs
- loxosceles genus
- brown
- sphingomyelinase D = tissue destruction and hemolysis
16
Q
Likely pt hx of widow bite?
A
- recent, less than 8 hrs
- gardening
- chopping
- using outdoor furniture
- cleaning a garage
- moving into a house that has not been occupied recently
- pt hx: bite usually on extremities (esp lower), most are initially asx or cause mild pain at site
- muscle pain is the most prominent feature in systemic rxns: extremity muscles, abdomen, back
17
Q
Common sxs of a widow bite? Infants and kids?
A
- muscle pain - extremities, abdomen, back
- tremor, weakness, shaking of extremity
- HA, N/V
- in infants and kids?
nonspecific
distressed and inconsolable
refusing food and drink
generalized erythema
18
Q
Physical findings - pt with widow bite?
A
- vital signs normal in 70% of pts
- musculoskeletal:
intermittent muscle rigidity and tenderness adjacent to bite or abdomen, chest or back, weakness, tremor, and myoclonus
diaphoresis: corresponds to affected muscles - at wound site:
blanched circular patch
surrounding red perimeter
central puncture
appears like a target: 50% - may see fang marks, may start swelling up and weeping, or blistering
19
Q
Dx of widow bite?
A
- primarily based on sxs/s w/ hx
- no specific lab studies:
leukocytosis
elevated creatinine
elevated liver enzymes - adults with cardiac RFs consider:
EKGs
cardiac enzymes
20
Q
DDx widow bite?
A
- MRSA
- surgical abdomen
- lyme
- myocardial ischemia or infarction
- tetanus
- rabies
21
Q
Envenomation for widow bite?
A
- mild: localized pain at bite normal vital signs - moderate: muscular pain at envenomated extremity extension of muscular pain to chest or abdomen local diaphoresis at bite normal vital signs - severe: generalized muscular pain in back, abdomen and chest diffuse diaphoresis abnormal vital signs
22
Q
Tx for mild envenomation?
A
- local measures: gently clean the bite with mild soap and water
- oral analgesia: acetaminophen, ibuprofen, oxycodone, hydrocodone
- oral muslce relaxers:
benzos (valium)
methocarbamol (robaxin) - tetanus prophylaxis if indicated
23
Q
Tx for moderate to severe envenomation?
A
- local wound care and tetanus prophylaxis as for mild envenomation
- parenteral opioids (morphine)
- parenteral benzos (lorazepam) to reduce the frequency and severity of muscle spasms
- antiemetic therapy: sublingual or IV ondansetron
- consider antivenom admin: consult with medical toxicologist prior to admin, carries small risk of anaphylactic rxns
preg C
24
Q
General characteristics of a brown recluse and the bite?
A
- has 6 eyes
- bites are usually sustained indoors
- typically on upper extremities, thorax, inner thigh
- notorious for sometimes causing skin necrosis
- S, W, MW areas
- cytotoxic enzymes
25
Sxs of a borwn recluse bite?
- local sxs: usually develop 8 hrs after a bite, usually painless initially, occasionally some minor burning that feels like a bee sting, severe pain at bite site after about 5 hrs
- systemic sxs:
malaise
N/V
fever
myalgias
26
Physical findings of a brown recluse bite? Most common finding?
- initially bite site is mildly red
- may reveal fang marks
- blistering (common)
- necrosis of skin and sub fat (less common)
- severe destructive necrotic lesions with deep wide borders (this is rare)
27
Dx of a brown recluse bite?
- based most often on hx and clinical presentation
- definitive:
a spider was observed inflicting the bite
spider recovered, collected, and properly ID by an expert entomologist
- if both conditions are not met, then other conditions must be excluded
28
DDx of brown recluse bite?
- bacterial
- deep fungal
- pseudomonas aeruginosa
- parasitic
- viral
- topical and exogenous causes
- venous
- neoplastic disease
- necrotizing disease
- necrotizing vasculitis
- diabetic ulcers
29
Tx of brown recluse bite?
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- local wound care:
clean with mild soap and water
apply cold packs
maintain affected part in elevated or neutral position
- pain management:
NSAIDs or opioids if necessary
- tetanus prophylaxis if indicated
- dapsone in some cases to prevent progression to necrosis and reduce pain
- no antivenom available in US
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