Insect Bites/Urticaria Flashcards

1
Q

What is the common clinical presentation of a spider bite?

A

Initial stinging, swelling, localized swelling, itching and inflammation

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2
Q

What are the severe reactions to spider bites and who are the culprits?

A

Black widow: pain within 30-60 minutes, then sweating, nausea, blurred vision, muscle cramps

Brown Recluse: redness, itching, pain within 6 hours; tissue necrosis if left untreated (cytotoxic)

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3
Q

What is the common clinical presentation of a tick bite?

A
Red papule at bite site, following may also occur:
	• Swelling
	• Blistering
	• Bruising
	• Itching
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4
Q

What is the severe reaction for a tick bite and who are the culprits?

A
Lyme disease: 
	• 3-30 days after bite --> erythema migrans rash beginning at bite site and expanding gradually, flu-like symptoms:
		○ Fever
		○ Headache
		○ Fatigue 
		○ Muscle and joint aches
		○ Swollen lymph nodes
	• Days-months after bite --> severe headache, facial palsy, severe joint pain and swelling, heart palpitations, inflammation of the brain and spinal cord 

Rocky Mountain Spotted Fever:
• 1-4 days after bite –> fever, headache, N/V, myalgia, maculopapular rash 2-4 days after onset of fever
• 5+ days –> altered mental status, coma, acute respiratory distress, necrosis, multiorgan system damage, petechial rash

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5
Q

What is the common clinical presentation of a mosquito bite?

A

Red, itchy papule develops within hours and subsides over a few days

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6
Q

What is the more severe reaction from a mosquito bite?

A

In patients who develop antibodies: large welts that last for several days

West Nile virus (2-15 days for appearance)
• Mild –> flu-like symptoms, possible rash
• Severe –> high fever, stiff neck, confusion, muscle weakness or degeneration

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7
Q

What is the common clinical presentation for a bee or vespid sting?

A

Pain, redness, swelling within 4-48 hours

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8
Q

What is the more severe reaction to a bee or vespid sting?

A

Extensive local reaction –> swelling over large area (whole limb) peaking at 48 hours and subsiding over 3-10 days

Systemic reaction –> headache, fever, N/V within 12-24 hours

Anaphylaxis –> trouble breathing or swallowing, swelling of lips or throat, rapid heart rate

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9
Q

What are the red flags warranting referral for an insect bite?

A
  • Bullseye appearance around lesion
    • Lesion is infected
    • History of severe reaction
    • Immunocompromised due to medication or conditions
    • Lesion persisted >7 days or is not improving after 24h of treatment

Specifically for bee/vespid:

  • Anaphylaxis
  • Severe local reaction (>10cm diameter)
  • Sting to tongue or mouth
  • Multiple stings
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10
Q

What are the prevention measures for stings?

A

avoid areas with nests or hives, wear clothing that covers skin, limit time spent outdoors at dawn and dusk

Other:
• Cover drinks to avoid swallowing bees/wasps
• Eat indoors
• Avoid scented products

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11
Q

What are the prevention measures for tick and mosquito bites?

A
  • avoid infested areas and standing by sources of water
  • wear clothing that covers skin
  • limit time spent outdoors at dusk and dawn
  • consider mosquito netting (esp for <6mo)

Ticks: light coloured clothing (make ticks more visible), wear clothing tight at ankles and wrists, wear clothing with permethrin, inspect tick-prone areas and pets before going indoors

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12
Q

What are the types of insect repellent available, how do they work, how do you use them and at what strengths are they used?

A

Deet: offensive to insects; apply sparingly, may cause skin irritation, may be fatal if ingested, NOT recommended for children <6mo unless travelling to high risk areas
○ 6mo-12yr <10% QD
○ 2-12yr, <10% TID
○ >12yr, 30% TID

Icaridin/Picaridin: conceals human attractants
○ 10% q5h, QID
○ 20% q7h, BID

Soybean oil: conceals human attractants and cools skin temp
PMD: may conceal human attractants, not recommended for children <3y
○ Apply PRN up to BID

Citronella oil: offensive smell/taste to insects, may cause skin irritation, requires frequent application, not recommended for <2yrs
○ Apply PRN

Metofluthrin: released as vapour to repel insects, activate clip on device PRN, may cause skin/respiratory irritation, tremors and sympathetic activation possible if ingested
○ ~12h/disk

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13
Q

What types of insect repellent are safe in pregnant and breastfeeding women?

A

ALL of the list are safe in pregnancy and breastfeeding except citronella oil and metofluthrin (no safety data available)

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14
Q

What are the non-pharmacologic strategies available for the treatment of insect bites?

A

Stinger should be removed asap to decrease local reaction
• Ticks best removed using tweezers
○ Grasp tick close to head and avoid twisting or pulling too quickly
○ Using petrolatum, gasoline or matches are NOT RECOMMENDED (may damage skin further)
• Stingers can be removed gently scraping side to side with tweezers, finger nail or credit card
○ DON’T pull stingers (may force more venom into skin)

Clean the bite/sting with soap and warm water to decrease risk of secondary infection

Ice or cool compress may be applied to provide symptomatic relief and reduce swelling
• Home remedies like oatmeal, baking soda baths, toothpaste or salt and vinegar applied to the site may relieve symptoms but are not well studied

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15
Q

What are the pharmacologic options for treating insect bites and stings?

A
  • OAH
  • oral analgesics
  • hydrocortisone 0.5-1%
  • topicals containing local anesthetics, astringents, counter-irritants or ammonia/baking soda
  • oral corticosteroids
  • epinephrine (in cases of anaphylaxis)
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16
Q

Why and how are OAH used in the treatment of insect bites and stings?

A

reduce itching, swelling, and redness
• May be more effective than topical products which should be avoided due to risk of contact dermatitis
• 1st (diphenhydramine) and 2nd (cetirizine, desloratadine) generation are equally as effective but 2nd are better tolerated
• Cetirizine has an onset of 15-30 min but is more likely to cause sedation

17
Q

Why and how is hydrocortsione used for the treatment of insect bites and stings?

A

Hydrocortisone 0.5-1%: applied QID for MAX 7 days to reduce itching, swelling and redness
• Can be prescribed by a pharmacist if covered or warranted for other reasons
• Studies on efficacy of TCS for insect bites and stings is limited
• Use cautiously on areas of broken skin
• Creams work best

18
Q

Why and how are oral corticosteroids used in the treatment of insect bites and stings?

A

Oral Corticosteroids: may be needed for more severe local reactions
• Prednisone 1mg/kg (pharmacists cannot prescribe)
• Doxycycline -> post-exposure/prophylaxis/treatment of Lyme disease

19
Q

When should the patient monitor and when does the pharmacist follow up on the treatment of insect bites and stings?

A

Patients or caregivers should monitor condition daily when self-management is appropriate, pharmacists should follow up in 24 hours
• If there is no improvement or worsening condition, refer

20
Q

What is considered acute versus chronic urticaria?

A

Acute is <6 weeks

Chronic is >6 weeks

21
Q

What is the common clinical presentation of urticaria?

A

• Appears as red or skin-coloured wheals
• Raised
• Well-circumscribed
• Often with central pallor
• Range in size (less than 1 cm to several cm)
• May coalesce as they enlarge
• Intensely pruritic
• May interfere with work or sleep
• May burn or sting
• May effect any part of the body but areas compressed by clothing or rub together may be affected more dramatically
• Generally last for 24 hours or less
• Can last from minutes to months or years
Do not bruise or scar unless there was skin trauma from scratching or they are associated with underlying disease

22
Q

What are the red flags warranting referral of a patient presenting with urticaria?

A

Referral for further assessment needed:
• Angioedema
• Stridor, wheezing, or other indicators of respiratory disease
• S/S of systemic illness
• Lesions are hyperpigmented, bruised, blistered or ulcered
• Lesions have persisted for >48 hours

23
Q

What are the goals of therapy for treating urticaria?

A
  1. Identification and removal of cause of skin reaction
    1. Providing symptomatic relief until spontaneous resolution occurs
    2. Ensuring appropriate care in case of more severe reaction
24
Q

What are the non-pharmacological strategies for the treatment of acute and chronic urticaria? (6)

A

Avoidance of identified trigger

Wear loose fitting clothing

Take cool baths
• Use gentle, fragrance-free soaps and detergents

Applying cool compresses

Ensure proper skin protection
• Keep fingernails short to avoid scratching

AVOID alcohol and medications like acetylsalicylic acid and NSAIDS

25
Q

When are pharmacological interventions indicated in the treatment of urticaria?

A
  • trigger avoidance is not possible
  • no trigger can be identified
  • symptom relief is needed despite trigger avoidance
26
Q

What is the first line pharmacological treatment in the management of acute urticaria?

A

1st Line –> 2nd generation H-1 Antihistamines: reduce wheal formation, pruritis and disruption of sleep
• Longer acting, relatively non-sedating
• 1st generation may be indicated in younger, healthy patients to help with sleep
• No strong evidence to suggest one agent is superior
• TAH not recommended because of contact dermatitis
• If they don’t work, an H-2 antihistamine like ranitidine may be added
○ Generally not required
○ Limited data to support

27
Q

When are oral corticosteroids indicated in the management of acute urticaria?

A

when angioedema is present or symptoms have persisted for more than a few days
• Patient referral required

28
Q

What are the first line pharmacological options for the treatment of chronic urticaria?

A

1st line –> H-1 antihistamines
• Dosed daily rather than PRN
• Some evidence says cetirizine may be modestly more effective than other agents for chronic hives
• If insufficient control in 2-4 weeks; dose can be titrated up to 4x usual dose
○ Increases risk of adverse effects
○ Not recommended in self-care

29
Q

What is the step up in treatment from first line pharmacological options in the treatment of chronic urticaria?

A

Next steps:
• Omalizumab: can be added if there is not enough control in 2-4 weeks
• Cyclosporine: can be added onto OAH if there is not sufficient control within 6 months
○ Requires specialist supervision

30
Q

What are the alternative pharmacological options for the treatment of chronic urticaria when needed for safety or cost reasons?

A

• H-2 receptor antihistamines can be added although not directly involved in itch
• Leukotriene receptor antagonist
○ Useful in patients with NSAID intolerance or cold urticaria
○ Pharmacists cannot prescribe for hives
• Doxepin
Pharmacists cannot prescribe, need to refer

31
Q

If symptoms of chronic urticaria are severe, what else can be added to the treatment plan?

A

Short course corticosteroids may be added if symptoms are severe
• Potent topical corticosteroids may be beneficial for localized delayed-pressure urticaria
○ Pharmacists CAN prescribe for hives