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
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
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
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
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
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
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
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)
9
Q
Where do funnel web spiders live?
A
- like houses
- some species in NW but bite doesn’t cause serious rxns in humans
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
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)
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
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
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
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
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
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
18
Q
Stings from what group result in more fatalities than any other arthropod?
A
- hymenopterans
- bees, wasps, ants
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
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)
