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Emergency Medicine > Bites and Infestations > Flashcards

Bites and Infestations Flashcards

1
Q

Dangerious spiders?

A
  • black widows
  • brown recluse or fiddlebacked
  • funnel web
- broad range of rxns:
local rxns (necrotic lesions), syst rxns, and allergic rxns

tarantulas: non-aggressive and rarely bite, body hairs are venomous and can induce anaphylactic rxns

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2
Q

Criteria that must be met to attribute a rxn to spider bite?

A
  • spider must be seen during biting
  • spider must be recovered, collected and sent for ID
  • other conditions that could explain rxn must be ruled out
  • most suspected spider bites were found to have a diff cause that actual spider
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3
Q

minor local rxn due to arachnid?

A
  • majority of time a spider bite will only cause minor local rxn
  • fang markings: 1 or 2 sep ports of entry
  • local erythema w/ bright red tender nodule appearing w/in min w/ subsequent induration
  • no blister
  • lasts about 7-10 days
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4
Q

Necrotizing local rxn due to arachnid?

A
  • brown recluse (black widow bites don’t generally cause necrotic lesion)
  • initial erythema that expands to 5-15 cm followed by blister w/in 15-36 hours
  • blister opens and oozes w/in 24 hrs
  • subsequent ulcer w/ crater
  • lesion can take several months to heal and leave permanent scarring
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5
Q

Systemic and allergica rxn from arachnids?

A
  • systemic:
    sxs may include fever, myalgias, fatigue, lymphadenopathy, rarely hemolysis and coagulopathy
  • allergic:
    may be limited to localized urticaria or may be systemic: anaphylaxis
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6
Q

Characteristics of black widows?

A
  • found predominantly in warmer climates
  • live in piles of firewoord, old lumber, rock biles, hay
  • not aggressive, timid biting only when bothered or protecting egg sac
  • hundreds of bites from brown recluse spiders are reported for each black widow bite
  • may have immediate sharp pain w/ bite, may also be painless and go unnoticed
  • two fang marks visible in approx 80% of cases
  • live in Western half of US
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7
Q

Phases of black widow bites?

A
  • mild rxns resolve w/in 12 hrs
  • systemic rxn known as latrodectism has 3 phases:
    1) exacerbation phase: up to 24 hrs following bite - muscle spasms near bite but can occur anywhere in body esp abdomen, and lower extremities, autonomic stim may include sweating, nausea, vomiting, tachycardia, tachypnea, restlessness, HTN and HA
  • coma and death can ensue but is rare and is usually in a child
    2) dissipation phase (1-3 days following bite): sxs decline in most cases w/o specific tx
    3) residual phase (wks to months following bite): muscle spasms, tingling, nervousness, weakness may occur
  • antivenom is available for pts experiencing severe systemic rxns
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8
Q

Characteristics of brown recluse spiders and bites?

A
  • live in human dwellings
  • distributed in midwest and south central region of US: below interstate 80 (missouri)
  • bites are trivial in more than 95% of cases
  • occasionally cause severe local necrotic rxn
  • systemic rxn known as loxoscelism can result in syndrome assoc w/ hemolysis (may result in death but very rare)
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9
Q

Where do funnel web spiders live?

A
  • like houses

- some species in NW but bite doesn’t cause serious rxns in humans

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10
Q

Tx of local nonnecrotic simple rxns to spider bites?

A
  • cleaning w/ soap and water
  • ice packs
  • observing for 24 hrs to see if systemic involvement
  • tetanus prophylaxis recommended
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11
Q

Tx of necrotic lesions?

A
  • initially tx as simple rxns
  • if center less than 2 cm large - conservative tx
  • if larger than 2 cm - systemic corticosteroids for 5-7 days
  • aluminum acetate soaking, clean dressings, debridement once ulceration develops
  • abx if signs of secondary bacterial infection
  • on rare occasions will reqr surgical revision (including skin grafting)
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12
Q

Tx of systemic rxns?

A
  • supportive therapy directed at involved organ systems
  • loxoscelism w/ extensive hemolysis tx as other hemolytic states
  • careful hydration
  • analgesics
  • calcium gluconate for relief of muscular pain w/ lactrodectism was found not to be effective
  • benzos and opioids generally used for spasms and pain w/ lactrodectism
  • prompt antivenom considered for black widow bite IF pt having typical muscle spasms and bite was noticed or fang markings ID
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13
Q

Caution w/ black widow antivenom?

A
  • don’t give indiscriminately

- severe SEs occur in up to 9% of pts: may include serum sickness (horse serum) and anaphylaxis

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14
Q

Tx od allergic rxns?

A
  • H1 and H2 blockers for local urticarial rxns
  • epi is appropriate for anaphylaxis
  • topical steroids for large localized lesions
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15
Q

Scorpions found in US?

A
  • most dangerous ones found outside US
  • w/in US - one scorpion that is considered to be dangerous - bark scorpion
  • found mostly in Arizona, NM, SE california, texas and Mexico
  • use venom only for defense and rarely sting their prey
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16
Q

Presentation of scorpion bite?

A
  • neurotoxin can cause prolonged and excessive depolarization
  • systemic sxs not common but can be severe esp in kids:
    pain and paresthesias in stung extremity - may become generalized
  • abnormal EOMs, blurred vision, pharyngeal muscle incoordination and drooling
  • excessive motor activity may appear seizure like
  • may have N/V, tachycardia, severe agiitation
  • w/o antivenom sxs can last 24-48 hrs
  • deaths are rare
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17
Q

Tx of scorpion bite?

A
  • initially supportive w/ analgesics
  • antivenom only available in AZ and production has been stopped - shold be reserved for cases of severe systemic toxicity
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18
Q

Stings from what group result in more fatalities than any other arthropod?

A
  • hymenopterans

- bees, wasps, ants

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19
Q

Bee stings?

A
  • honeybees and bumblebees docile, sting only when provoked
  • males don’t have stingers
  • africanized honeybees (killer bees) very aggressive:
    no more toxic than nonaggressive bees
  • worry about venom toxicity w/ africanized bees - still greatest worry is an anaphylactic rxn
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20
Q

Wasp stings?

A
  • most of allergic rxns for hymenoptera occur from wasps and relatives (hornets and yellowjackets)
  • much less docile than normal honeybees and may be disturbed by work taking place around the nest
  • only females have stingers and unlike bees can withdraw stingers which allows them to sting mult times
21
Q

Hymenopteran venom?

A
  • melittin big player - can cause degranulation of basophils and mast cells
  • venom of all hymenopterans share many of the same components and therefore cross sensitization may occur
22
Q

Presentation of hymenopteran sting?

A
  • local rxn
  • anaphlactic
  • toxic
  • delayed
23
Q

Local reaction to hymenopteran sting?

A
  • urticarial lesion contiguous w/ sting site
  • can involve 1 or more neighboring jts w/ severe local rxn
  • local rxn of mouth or throat can produce airway obstruction
  • if local rxns become increasingly severe - can increase likelihood of systemic rxn down the road
  • tx:
    remove stinger, wash site w/ soap and water, ice packs, antihistamines, and analgesics
24
Q

Anaphylactic rxn of hymenopteran sting?

A
  • systemic rxn which may range from mild to fatal, death can occur in min.
  • majority of rxns occur w/in 1st 15 min and nearly all w/in 6 hrs
  • initial sxs: itchy eyes, facial flushing, generalized urticaria, dry cough
  • sxs may then intensify rapidly w/ chest or throat constriction, wheezing, dyspnea, cyanosis, abdominal cramps, diarrhea, N/V, vertigo, chills, fever, laryngeal stridor, shock, syncope, involuntary bowel or bladder action, and bloody frothy sputum
25
Q

Tx priorities for hymenopterans - anaphylaxis?

A 
- ABCs then depending on severity:
O2 by NC or FM
epi 0.3-0.5ml 1:1000 SQ
IV access, 1 or 2 large bore IVs of NS
diphenhydramine 50 mg PO/IV
famotidine 40 mg PO or 20 mg IV
methylprednisolone 125 mg IV
26
Q

Toxic rxn of hymenopteran sting?

A
  • mult stings and therefore person has systemic response

- can mimic anaphylaxis but there is generally greater frequency of N/V, and diarrhea

27
Q

Delayed rxn of hymenopteran sting?

A
  • immune complex mediated rxn
  • appears 5-14 days after sting
  • sxs: fever, malaise, HA, urticaria, lymphadenopathy, polyarthritis (serum like sickness) - not anaphylactic rxn
  • delay from sting to sxs makes this hard to dx
28
Q

Ant bites?

A
  • pontential x-reactivity w/ other hymenoptera
  • individual stings may produce systemic toxicity in sensitized individuals
  • tendency to attack in great numbers when provoked (fire ants have simultaneous stinging mechanism)
  • local lesions: papule that may become sterile pustule in 6-24 hrs
  • tx: localized wound care
29
Q

3 major groups of venomous snakes?

A
  • vipers: crotalinae subfamily - rattlesnakes
  • elapidae: coral snakes
  • hydrophiidae
30
Q

Rattlesnake bites?

A
  • mostly found in southwest US, some in Eastern US
  • some in MT - 4-5 bites reported/year
  • rattlesnakes don’t always rattle b/f striking
  • venom can cause local tissue injury, systemic vascular damage, hemolysis, fibrinolysis, and neuromuscular dysfxn
  • 25% are dry bites where venom effects don’t develop
31
Q

Presentation of rattlesnake bite?

A
  • cardinal manifestations include presence of one or more fang marks, localized pain, and progressive edema extending from bite site
  • other early sxs and signs include: N/V, weakness, oral numbness, tachycardia, dizziness, muscle fasciculation
  • ecchymoses may appear as venom can consume fibrinogen and platelets
32
Q

Tx for rattlesnake bites?

A
  • txs such as suction and incision are dangerous and shouldnt be done
  • ice tx also shouldnt be done (ice water immersion worsens venom injury)
  • tourniquets shouldn’t be used (may obstruct arterial flow and cause ischemia)
  • constriction band may be of some use, key is to ensure there are distal pulses and capillary filling
  • nothing should delay the person from seeking immediate definitive medical care of the admin of antivenin
33
Q

Initial emergency management for rattlesnake bite?

A
  • immobilize limb, est IV access, admin O2, tx w/ advanced life support as necessary
  • ED management:
  • antivenin is mainstay (polyvalent Crotalidae immune fab) for any bites that show evidence of progressive signs and sxs
  • aggressive supportive care w/ isotonic fluids and vasopressor agents are needed for hypotension
  • blood component replacement may be necessary if active bleeding
34
Q

Coral snake bites?

A
  • primarily found in SE US: Texas and AZ
  • account for 20-25 bites in US/year
  • venom primarily composed of neurotoxic components that don’t cause marked local injury
  • sxs primarily neurologic and include: tremors, salivation, dysarthria, dipolopia, fixed and contracted pupils, dysphagia, dyspnea, and seizures
  • death can result from paralysis of resp muscles
  • signs and sxs may be delayed up to 12 hrs
35
Q

coral snakes rhyme?

A
  • red and yellow kill a fellow = coral snake

- red and black venom lack = milk snake

36
Q

Management of coral snake bite?

A
  • pt should be admitted for observation
  • baseline and serial pulmonary fxn measures
  • antivenin for pts who have definitely been bitten
  • it may not be possible to prevent further effects or reverse effects that have already developed
  • ventilatory support as reqd
37
Q

When does transmission usually occur by tick? 2 main tick diseases in US?

A
  • disease transmission usually occurs near end of blood meal as tick becomes engorged
  • 2 diseases: lyme disease (Borrelia burgdorferi) spread by deer ticks, and RMS (rickettsia ricketsii) - dog ticks
38
Q

What diseases do ticks carry?

A

ticks leading carriers (vectors) of diseases to humans in US, 2nd only to mosquitos worldwide

  • lyme
  • babesiosis
  • erlichiosis
  • RMSF
  • southern tick assoc rash (STARI)
  • tick borne relapsing fever
  • tularemia
  • anaplosmosis
  • colorado tick fever
  • powassan encephalitis
  • Q fever
39
Q

Correct way to remove a tick?

A
  • use fine tweezers to grab tick close to skin surface
  • pull backwards gently and firmly, don’t jerk or twist
  • don’t squeeze, crush or puncture the body of tick
  • wash hands and skin thoroughly w/ soap and water
  • if any mouth parts of tick left in skin - leave it alone - it will be expelled eventually, attempt of removal may result in trauma or infection
40
Q

What sxs should you monitor for lyme disease?

A
  • sxs may not be obvious for days or weeks after tick bite:
    flu like sxs, fever, weakness, jt pain, swelling, SOB, erythema migrans - usually is salmon color and expands over a few days or weeks and reaches 20 cm in diameter, center of rash can then appear a lighter color giving it the bulls eye appearance
  • approx 80% of people w/ lyme develop EM
41
Q

What people should receive preventative tx w/ abx?

A

only people that meet all of the following criteria:

  • attached tick ID as adult or nymphal deer tick
  • tick is est to have been attached for longer than 36 hrs

abx tx can begin w/in 72 hrs of tick removal

  • pt can take doxycycline (not breastfeeding, preg or kid under 8)
  • recommended dose: 200 mg for adult and 4 mg/kg for kid over 8
42
Q

3 distinct presentations of lice?

A
  • head lice - pediculus humanus capitis
  • body lice - pediculus humanus corporis
  • pubic lice - pthirus pubis
43
Q

MC pop affected by lice? dx? Tx?

A
  • head lice is MC form of lice infestation
  • kids 3-10 MC affected
  • MC transmitted via head to head contact
  • dx is by demonstration of lice and nits
  • OTC agents: nix lotion (permethrin 1%) rid, A200 and pronto shampoos (pyrethrin products) are usually effective (liquid over 2)
  • wash and dry all bed linesn that have been in contact w/ infested person on hot cycle
  • not necessary to shave person’s head
44
Q

Body lice spread? Tx?

A
  • live in seams of clothing and then transfer to human host to feed
  • bedbugs are related to lice (probably responsibe for most spider bites)
  • tx: conservative -
    wash body thoroughly
    wash and dry all exposed linen and clothes in hot cycles, anti-lice agents usually not needed if clothing is thrown away and bed linens are washed thoroughly
  • vaccuum floors and furnitur and throw vacuum bag away
45
Q

How is pubic lice transmitted? Tx?

A
  • trasmitted by direct sexual contact
  • intense itching of pubic area is characteristic
  • tx w/ anti-lice agents and repeat in 7-10 days
  • remove nits w/ fine toothed comb
  • tx contacts if lice and nits are found
  • wash and dry all clothes and bed linens in hot cycles
46
Q

Scabies infestation? Dx?

A
  • caused by microscopic mite (sarcoptes scabiei) - incubation can be several weeks b/f sxs, earlier w/ subsequent infection
  • sxs caused by mite’s tunneling below skin which causes a localized allergic rxn
  • dx:
    extremely itchy rash w/ crusting, linear burrows, crusting lesions, other family members
  • frequently occurs b/t fingers and toes, buttocks, creases of elbows and waist of genitals
  • usually spread by skin-skin contact
47
Q

Tx of scabies?

A
  • MC tx w/ 5% permethrin cream (Elimite)
  • generally safe for use in kids as young as 2 months
  • apply from head to bottom of feet, paying special attention to skin folds and creases
  • permethrin is left on for 10-14 hrs and then washed off in shower
  • itching and rash may last up to 2 wks after tx
48
Q

Tx of bed bugs?

A
  • itchy red spots assoc w/ bedbug bites usually disappear on their own w/in 1 wk or 2. Might speed your recovery by using:
    skin cream containing hydrocortisone
    oral antihistamine: such as diphenydramine (benadryl)

Emergency Medicine (22 decks)

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