Infestations Flashcards

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1
Q

What is pediculosis capitis?

A
  • Head lice
  • Causes intense pruritis of scalp
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2
Q

Where is pediculosis capitis common?

A
  • Highly contagious often in schools and day care centers
  • Anywhere that people live in close quarters: nursing homes, dorms, prisons

head lice

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3
Q

Characteristics of louse in pediculosis capitis

A
  • 1-3 mm long, flattened brownish gray elongated bodies, 3 pairs of legs and claws
  • Small, wingless ectoparasites
  • Lifespan 14-18 days
  • Nits .5-1 mm in diameter and opalescent, grey-white specks firmly attached to individual hair shafts
  • Microscopy reveals oblong structure attached to hair at acute angle with lobular breathing apparatus at its superior end
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4
Q

Where is pediculosis capitis/pubis nit found? Humanus?

A
  • Capitus/pubis: hair shaft
  • Humanus: seams of clothing/bedding
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5
Q

Epidemiology of pediculosis capitis

A
  • MC in females
  • White school aged children/mothers
  • Warmer months
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6
Q

How can you differentiate between seborrheic dermatitis and pediculosis capitis?

A
  • Seborrheic dermatitis: greasy, yellow, irregular scales that are easily removable
  • Pediculosis capitis: adhere to hair shaft
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7
Q

How do you differentiate between pediculosis capitis and tinea capitis?

A
  • Tinea capitis has pruritis and lymphadenopathy but is associated with alopecia and no nits found on examination
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8
Q

How do you differentiate between pediculosis capitis and psocid lice?

A
  • Psocid lice live off plant detritus and may be found on child who plays in wooded areas but are morphologically distinct from pediculosis humanis capitis
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9
Q

Transmission of pediculosis capitis

A
  • Direct head-to-head contact
  • Fomites (clothes, brushes, linens, combs, hats)
  • Lice live approx 30 days on host and <1 day off host
  • Eggs hatch within 7-10 days
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10
Q

What should you look for in the scalp hair in pediculosis capitis?

A
  • Lice and nits in scalp hair
  • Maculae ceruleae or purpuric stains on skin of occipital scalp and nape of neck
  • Occipital lymph nodes may swell as result of secondary infection
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11
Q

Diagnostic pearls for pediculosis capitis

A
  • Pyodermas (infection with bacteria causing pus under the skin) in the scalp along with occipital and cervical lymphadenopathy suggestive
  • Nits oval, tenacious hair concretions
  • Nits not easily removed from hair (unlike seb derm)
  • Nits fluoresce and are readily detected with a wood’s lamp
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12
Q

Best tests for pediculosis capitis

A
  • Demonstration of lice or nits on hair visually or under microscope
  • Wood’s lamp with fluorescent nits
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13
Q

Management pearls for pediculosis capitis

A
  • Increasing resistance of lice to permethrin. If no response with permethrin, use alternative
  • Manual nit removal with fine comb may be used as adjuvant to topical therapy
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14
Q

Precautions for pediculosis capitis

A
  • Standard and contact
  • Isolate patient
  • Wear gowns and gloves
  • Limit patient transport
  • Avoid sharing patient-care equipment
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15
Q

Treatment of pediculosis capitis

A
  • Prescriptions reserved for patients with proven infestations that do not respond to OTC
  • Manual nit removal with fine comb adjuvant to topical therapy
  • Most herbal and home remedies unproven in effectiveness and safety
  • Do not treat a child unless live lice or eggs (not empty nit cases) present
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16
Q

OTC for pediculosis capitis

A
  • Permethrin 1% (Nix): apply to dry hair, rinse after 10 minutes
  • Repeat in 1-2 weeks
  • Pyrethrins with piperonyl butoxide (RID, pronto): apply to dry hair, rinse after 10 minutes
  • Repeat in 1-2 weeks
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17
Q

Prescriptions for pediculosis capitis

A
  • Spinosad- adults and children older than 4 years
  • Malathion .5% lotion
  • Permethrin 5%: not for infants younger than 2 months
  • Ivermectin formulated lotion: adults and children 6 months and older, not used in babies younger than 6 months or pregnant women
  • Oral ivermectin: not for children younger than 5 or weighing less than 15 kg
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18
Q

How is spinosad applied?

A
  • In adults older than 4 years
  • Applied for 10 minutes if live lice seen at 1 week second treatment
  • Combing not necessary
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19
Q

What is the first line lice treatment by the american academy of pediatrics?

A

Spinosad

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20
Q

How is malathion applied?

A
  • Apply to dry hour and rinse after 8-12 hours
  • Repeat after 1-2 weeks
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21
Q

How is permethrin 5% applied?

A
  • Off label
  • Apply to dry hair, rinse after 8-12 hours
  • Repeat in 1-2 weeks
  • Not in infants aged younger than 2 months
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22
Q

How is ivermectin formulated lotion applied?

A
  • Treatment applied for 10 minutes
  • Adults and children 6 months and older, not used in babies younger than 6 months or in pregnant women
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23
Q

How is oral ivermectin (off-label) used?

A
  • 200 micrograms/kg in one oral dose
  • Repeat in 7-10 days
  • Not indicated in children aged younger than 5 years or weighing less than 15 kg
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24
Q

How is pediculosis capitis with eyelid involvement treated?

A
  • Application of petrolatum twice daily to eyelid margin for at least 8 days
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25
Q

What is pediculosis corporis?

A
  • body lice
  • Infestation with pediculosis humanis corporis
  • 2-4 mm, wingless, blood-sucking arthropod whose preferred hosts are human beings
  • Rarely found on skin, mainly clothing
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26
Q

Signs and symptoms of pediculosis corporis

A
  • Extremely pruritic, especially at night (lice move from clothing to body to feed)
  • Bites leave macules and papules concentrated in intertriginous regions
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27
Q

Epidemiology of pediculosis corporis

A
  • Found in all countries and climates
  • May infest any age group
  • No racial or sex predilection
  • Associated with poor hygiene, poverty, and homelessness
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28
Q

Clinical manifestations of pediculosis corporis

A
  • Multiple erythematous papules that correspond to insect bites
  • Found anywhere on body but most concentrated in areas covered by clothing: groin, axillae, trunk, buttocks
  • Maculae cerulea, blue-gray macules pathognomonic for lice infestation may be present
  • Excoriations and/or impetiginization
  • Exam of clothing may reveal nits, feces, blood stains, or insects themselves

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29
Q

What is “vagabond disease?”

A
  • Body louse infestation
  • Individuals that are infested for years may develop vagabond skin - thickened and darkened skin after a long period of bites and scratching or rubbing
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30
Q

Best tests for pediculosis corporis

A
  • Close examination of clothing for lice, nits, and feces (most concentrated at clothing seams)
  • Finding of a live louse or viable nit confirms diagnosis
  • Wood’s lamp fluoresce yellow-green
  • Can shake patient’s clothing out over white paper and examine the debris that falls off - pieces of tape can be used to pick up insects for exam
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31
Q

Management pearls for pediculosis corporis

A
  • Examine patient for pubic and head lice
  • If clinical suspicion warrants, test for one of arthropod borne diseases transmitted by p. humanus corporis –» typhus (rickettsia prowazekii), relapsing fever (borrelia recurrentis), trench fever (bartonella quintana)
  • Mainstay of treatment = eradicating infestation
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32
Q

Precautions for pediculosis corporis

A
  • Standard and contact
  • Isolate patient
  • Wear gloves and gown
  • Limit patient transport
  • Avoid sharing patient-care equipment
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33
Q

Patient education for pediculosis corporis

A

Proper hygiene

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34
Q

Treatment of pediculosis corporis

A

Treat clothing and fomites
* Wash all clothing and linens with hot water and dry on high heat
* Discard or avoid using heavily infested items for 2 weeks (seal in plastic bags)
* Iron seams of furniture with hot iron
* For heavy infestations 5% permethrin cream or lotion head-to-toe for 8-14 hours

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35
Q

What is pediculosis pubis?

A
  • Pubic lice or crabs
  • Highly contagious
  • Sexually transmitted parasitic infection with louse, phthirus pubis
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36
Q

How is pediculosis pubis spread

A
  • Person to perosn by close physical contact
  • Occassionally spread via fomites such as clothing or linens
  • Household pets do not play role in transmission
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37
Q

Where/who most commonly has pubic lice

A
  • Sexually active individuals
  • Terminal hair, typically pubic and perianal regions
  • Infestations may also be in eyelashes, eyebrows, and other facial hair, as well as chest and axillary hair
  • Scalp infestations in tightly curled hair
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38
Q

Progression of pediculosis pubis

A
  • Incubation > 1 week from contact
  • Eggs (nits) cemented to hair shafts with chiin and difficult to remove
  • Lice hatch in 6-10 days
  • Lifespan = 1 month
  • Not able to survive without feeding within 24 hours

Chitin = fibrous substance consisting of polysaccharides and forming constituent in exoskeleton of arthropods

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39
Q

Clinical manifestations of pediculosis pubis

A
  • Extreme pruritis secondary to saliva/anticoagulant injected during feeding
  • Lice visible to naked eye
  • Erythematous macules or papules present at feeding sites
  • Wheals can be appreciated as acute reaction
  • Small pinpoint bleeding on intimate clothing
  • +/- inguinal lymph node swelling
  • +/- maculae cerulae, or blue-gray macules seen at feeding sites on patients with long standing infestation
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40
Q

Appearance of lice/nits in pediculosis pubis

A
  • Lice visible to naked eye and with dermatoscope 1-3 mm in diameter, nits smaller but may be visible and tightly adhered
  • Adult louse with legs grasping hair shaft and insertion of mouth to skin
  • Nits - brown and full in shape, indicating presence of a nymph, or more translucent and flat in shape when empty
  • Nits may be mistaken for crusts or hair casts when attached near the ostia of hair follicles
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41
Q

Clinical diagnosis of pediculosis pubis

A
  • Severe pruritis = main symptom
  • Physical exam and additional tools such as dermoscopy, tape for specimen collection, or Wood’s lamp for fluorescence of nits may prove useful
  • Evaluate all hair bearing areas including facial hair, axillary hair, and chest hair
  • Finding louse is diagnostic
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42
Q

Management pearls for pediculosis pubis

A
  • Sexual partners within the prior month should be notified and treated
  • Avoid sexual contact until they and their partners have been treated and reevaluated to rule out persistent disease
  • Condoms do not prevent transmission of infestation
  • 30% have another STI so ROS and lab screening encouraged
  • Thorough history to recognize abuse or neglect if child
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43
Q

Steps for containment of pediculosis pubis

A
  1. Machine wash (130F) and dry any clothing, linens, or towels worn in 3 days prior to treatment
  2. If unable to launder, dry clean and stor in air-tight plastic bags for 2 weeks to starve lice and nits
  3. Soak combs and brushes (if used in affected areas) in very hot water for minimum of 5 mins
  4. Avoid sharing clothes, linens, and towels if infestation suspected
  5. Thorough cleaning of living quarters recommended
44
Q

Treatment for adults with pediculosis pubis

A
  • Treatment OTC or Rx of all affected areas
  • Those with increased hair density should also treat adjacent areas
  • Shaving may help eradicate but not required, based on patient preference
  • Secondarily infected lesions treated with appropriate topical or systemic antibiotic
45
Q

Medication regimens preferred by CDC for pediculosis pubis

A
  • Permethrin 1% lotion/cream or mousse containing pyrethrins
  • Wash infested area and towel dry
  • Apply product generously to affected areas
  • Leave on for duration indicated on package label or insert
  • Following treatment, nits can be forcibly removed from hair shafts with fingernails or fine-toothed comb
46
Q

Indications for permethrin (Nix, elimite)

A
  • Scabies
  • Head lice
  • Body lice
  • Pubic lice
47
Q

CI for permethrin

A
  • <2 months old
  • Hx of hypersensitivity
48
Q

Vehicle for permethrin

A
  • Cream 5%, lotion/cream 1%
49
Q

MOA of permethrin

A

Neurotoxin resulting in respiratory paralysis of parasite

<2% absorbed

50
Q

What pregnancy category is permethrin?

A

B

51
Q

Dosing of permethrin?

A
  • Head lice: apply to washed hair, leave 10 mins, rinse and comb out nits/eggs, repeat in 7 days if needed
  • Scabies, body lice: apply cream from jaw-line to toes, leave 8-14 hr, rinse, repeat in 7 days if needed. Bathe prior to application
52
Q

SE of permethrin

A
  • Transient burning
  • Stinging
  • Pruritis
  • Redness
  • Swelling
53
Q

Indications for pyrethrin/piperonyl butoxide (RID OTC)

A
  • Scabies
  • Head lice
  • Body lice
  • Pubic lice
54
Q

Vehicle of pyrethrin/piperonyl butoxide (Rid OTC)

A
  • Lotion
  • Gel
  • Shampoo
55
Q

MOA of pyrethrin/piperonyl butoxide

A
  • Pyrethrin: neurotoxic to parasite
  • Piperonyl butoxide: synergistic to pyrethrin
56
Q

CI to pyrethrin/piperonyl butoxide

A

Hx of hypersensitivity to product or ragweed, <2 yo

57
Q

Pharmacokinetics of pyrethrin/piperonyl butoxide

A

Minimal absorption
Excretion in urine

58
Q

Pregnancy category of pyrethrin/piperonyl butoxide

A

C

59
Q

Dosing of pyrethrin/piperonyl butoxide

A
  • Apply to wet infested areas
  • Leave 10 minutes
  • Wash off thoroughly
  • Repeat in 7 days if needed
60
Q

SE of pyrethrin/piperonyl butoxide

A
  • Transient burning
  • Stinging
  • Pruritis
  • Redness
  • Swelling
61
Q

Drug class of malathion (Ovide -Rx)

A

Scabicidal agent/topical pediculicide

62
Q

Indication for malathion

A

Head lice

63
Q

CI for malathion

A

<6 y/o, hx of hypersensitivity to product

64
Q

Vehicle for malathion

A

Lotion .5%

65
Q

MOA of malathion

A

Neurotoxic by inhibiting cholinesterase

66
Q

Pharmacokinetics of malathion

A

minimal absorption, excretion unknonw

67
Q

pregnancy category of malathion

A

B

68
Q

Dosing of malathion

A
  • Apply to dry hair, leave 8-12 hours, wash thoroughly, remove nits with comb, repeat 7 days if needed
  • Flammable: do not use heat on hair after application
69
Q

SE of malathion

A
  • Transient stinging
  • Irritation
  • Contact dermatitis/chemical burn
70
Q

What medication is the last resort for adults with scabies, head/body/pubic lice?

A

Lindane

71
Q

MOA of lindane

A

Neurotoxicity resulting in seizure and death of parasite

72
Q

CI to lindane

A
  • Black box warning for lindane: neurotoxicity (seizures/death) with prolonged application
  • Avoid in infants/children, elderly
  • Avoid if weight <50 kg
  • Hx of seizure disorder
  • Open skin lesions
  • Severe liver diagnosis
  • Excessive ETOH use
  • Concomitant use of meds that lower seizure threshold
  • Banned in California
73
Q

Vehicle of Lindane

A

Lotion/shampoo 1%

74
Q

Dosing of lindane

A
  • Scabies/body lice: apply and massage thin layer onto from neck to feet x 8-12 hr
  • Wash off thoroughly (do not shower prior to application), no longer than 12 hrs CDC recommends 8
  • Head/pubic lice: apply 1-2 oz of shampoo on dry hair, leave 4 min, lather, rinse
  • Remove nits with comb
  • Do not repeat- may use other pediculicide in 1 wk if needed
75
Q

Side effects of lindane

A
  • Transient skin irritation
  • CNS toxicity (dizziness, ataxia, seizure, paresthesias)
  • Alopecia
  • Hematuria
  • Aplastic anemia
  • Hepatitis
  • Pulmonary edema
76
Q

Pharmacokinetics of lindane

A
  • Slow/incomplete absorption on intact skin
  • Metabolized - liver
  • Excretion - urine/feces
77
Q

Pregnancy category of lindane

A

C/lactation: express and discard milk for 24 hours post application

78
Q

What is scabies

A
  • Intensely pruritic eruption
  • Caused by mite sarcoptes scabiei var. hominis
  • Transmitted person-to-person contact and less frequently by fomites
  • Extremey contagious
79
Q

Epidemiology of scabies

A
  • Higher in children
  • Residents of long term care facilities
  • Sexually active persons
  • Overcrowding
  • Delays in daignosis
  • Poor public health awareness outbreaks in health care facilities can contribute to persistence
80
Q

How many mites is the typical scabies infestation

A

10-20 mites

81
Q

What is the pathophysiology of scabies?

A
  • Hypersensitivity to mite burrowing into and below stratum corneum of epidermis
  • Highly pruritic eruption 2-6 weeks after initial infestation
  • Without medical treatment, persists as mites lay eggs
82
Q

Clinical manifestations of scabies

A
  • Itch worse at night, just after getting into bed
  • Patient can’t stop scratching in exam room
  • Burrow is fine, thread-like line with terminal tiny black speck (mite)
  • Small erythematous papules mostly on flexor wrist, around axillae and areolae, interdigital web spaces, and umbilicus, and in genital and buttock regions
  • Classically spares head and neck areas
  • Areola in women and on penis and scrotum in men = highly suggestive
  • Secondary lesions due to scratching include excoriations, impetiginized lesions with crusts, and prurigo-like nodules
83
Q

Scabies diagnostic pearls

A
  • Look closely for burrow mites
  • Almost never found by scraping papules or excoriated lesions
  • Tiny black dot present at edge of intact linear papule represents mite
  • Dermoscopy helps: darker V-shaped structure leading the burrow represents head of mite, followed by burrow “jetliner with its trail” dark brown/black material in burrow corresponds to eggs and feces left by mite
  • Negative scabies prep does not rule out diagnosis, mites difficult to isolate
84
Q

What is crusted scabies?

A
  • Severe and highly contagious variation
  • Most often seen in immunocompromised or institutionalized
  • Typical scabies 10-12 mites, crusted cases will have thousands to millions
85
Q

Treatment of crusted scabies

A
  • Topical agent of choice: permethrin 5% full body application left on 8-14 hours (overnight)
  • Repeat in 1 week
  • AND oral ivermectin .2 mg/kg/dose on days 1,2,8, 9, and 15 (sometimes also day 22 and 29)
86
Q

Best tests for scabies?

A
  • Scabies prep
  • Crusted scabies: KOH solution to break down exess keratin
  • Skin biopsy not needed but can be helpful if uncertain
87
Q

How is scabies prep performed?

A
  • Place mineral oil on skin area
  • Take #15 blade and gently remove terminal end of burrow with tiny black speck
  • Place on glass slide, cover with cover slip, and examine under microscope for mite or its ova or fecal pellets, known as scybala
88
Q

Pharm Management of scabies

A
  • First line: permethrin 5% or Rid
  • Last resort: lindane (avoid in crusted scabies, increased risk of CNS toxicity)
  • Treat infested person and close physical contacts, even if asymptomatic
  • Repeat treatment after 1 week: reduce risk of reinfestation
  • Oral ivermectin (2nd line) for crusted or classic scabies
89
Q

How is oral ivermectin dosed?

A

2-3 doses separated by 1-2 weeks for heavy infestation

90
Q

Non pharm management of scabies

A
  • Tx any secondary bacterial infections appropriately (ok kinda pharm)
  • Apply clean clothing after application
  • Wash/dry all bedding/clothing/curtains/pillows on hot cycle
  • Vacuum and dust anything that can’t be washed
91
Q

Pt ed for scabies

A
  • Symptoms should improve within 3 days but pruritis can persist for up to 4 weeks after tx
  • Post tx pruritis: benadryl OTC at night
  • If severe/persistent: 14 day tapered dose of prednisone
92
Q

Indications for skin scraping

A
  • Scabies
  • Fungal infections
93
Q

Supplies needed for skin scraping

A
  • 15 scalpel blade
  • Microscope slide
  • Slide cover
  • Mineral oil or KOH
  • microscope
94
Q

Technique for fungal evaluation via skin scraping

A
  • Use scalpel to remove scale along border of the lesion
  • Transfer to slide, apply 1-2 drops of 10-20% KOH to slide
  • Allow to sit for 10-15 mins
  • Examine under microscope with low and high power
95
Q

Potential sources of error for skin scraping

A
  • Not obtaining adequate specimen
  • KOH: not allowing enough time to dissolve all healthy/keratin cells
  • Abrasive technique resulting in blood contamination
96
Q

Variations in venom in spiders

A
  • Almost all venomous, but only a few dozen can harm humans
  • Envenomation can range from skin lesions to systemic illness, and in rare cases even death
  • Although tarantulas have venom, usually cause illness from urticating hairs
97
Q

What does severity of spider bite depend on?

A
  • Type of spider
  • Amount of venom injected
  • Site of bite
  • Health and age of patient
98
Q

Clinical manifestations of widow spider bite

Black widow = lactrodectus mactans, found in woodpiles

A
  • Neurotoxic venoms with alpha-iatrotoxin major component
  • Systemic symptoms relating to cholinergic and catecholamine excess
  • Painful hypertension
  • Tachycardia
  • Palpitations
  • Diaphoresis
  • Anxiety
  • Shortness of breath
  • Hyperthermia or hypothermia
  • Excessive salivation
  • Nausea
  • Vomiting
  • Severe abdominal pain
  • Noticeable fang marks with development of halo-like lesion around bite
99
Q

What are recluse spiders?

A
  • Loxosceles genus
  • Found worldwide in temperate and tropical regions
100
Q

Recluse spider bite clinical manifestations

A
  • Local necrosis, and, rarely, severe systemic symptoms
  • Bite often initially painless
  • Pain, swelling, bullae, and ischemia minutes to hours later
  • Eventually ulcerate and become necrotic and gangrenous
  • DIC- disseminated intravascular coagulation can occur
101
Q

What is funnel web spider?

A
  • Pacific northwest hobo spider
  • Commonly known as aggressive house spider
102
Q

Venom of funnel-web spiders symptoms

A
  • Neurotoxic causes severe pain at bite site
  • Systemic symptoms can be rarely fatal within minutes
  • Necrotic skin lesions
103
Q

Tarantula bite manifestations

A
  • Relatively harmless bite
  • Urticating hairs result in local skin reactions, ocular problems, and allergic rhinitis
104
Q

What should you look for with a spider bite?

A
  • 2 small puncta
  • Erythema and edema
  • Necrotic or dusky center within a red, inflammatory plaque characteristic
  • Brown recluse spider bites vesicles and bullae can present early (between 12 and 24 hours after envenomation erythema, ischemia, and necrosis “red, white, and blue sign”) –> painful, full-thickness necrotic plaques
  • Black widow bites = local sweating, piloerection, redness and mild edema
  • Systemic symptoms such as muscle pain, cramps, abdominal pain, salivation, lacrimation, sweating, tremors more prominent than skin findings
105
Q

Diagnosis of spider bites

A
  • Clinical
  • Spider collection with positive identification is gold standard
106
Q

If systemic involvement due to brown recluse spider suspected, what should be checked?

A
  • Evidence of hemolysis
  • Serial hemoglobin and plasma-free haptoglobin levels
  • Monitor for rhabdomyolysis, renal failure, and disseminated intravascular coagulation
  • Any serous or purulent drainage should be cultured to rule out MRSA infection
107
Q

Treatment of spider bites

A
  • Collection and ID of spider, if possible
  • Wound irrigation
  • Rest, cold compresses, elevation of affected extremity
  • Symptomatic treatment as indicated
  • Tetanus prophylaxis as indicated
  • Conservative local debridement of clearly necrotic tissue
  • Antivenom as indicated
  • For necrotic lesions, treatment with dapsone within first 36 hours has been advocated, but remains controversial