Insect Bites/Urticaria Flashcards
What is the common clinical presentation of a spider bite?
Initial stinging, swelling, localized swelling, itching and inflammation
What are the severe reactions to spider bites and who are the culprits?
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)
What is the common clinical presentation of a tick bite?
Red papule at bite site, following may also occur: • Swelling • Blistering • Bruising • Itching
What is the severe reaction for a tick bite and who are the culprits?
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
What is the common clinical presentation of a mosquito bite?
Red, itchy papule develops within hours and subsides over a few days
What is the more severe reaction from a mosquito bite?
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
What is the common clinical presentation for a bee or vespid sting?
Pain, redness, swelling within 4-48 hours
What is the more severe reaction to a bee or vespid sting?
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
What are the red flags warranting referral for an insect bite?
- 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
What are the prevention measures for stings?
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
What are the prevention measures for tick and mosquito bites?
- 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
What are the types of insect repellent available, how do they work, how do you use them and at what strengths are they used?
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
What types of insect repellent are safe in pregnant and breastfeeding women?
ALL of the list are safe in pregnancy and breastfeeding except citronella oil and metofluthrin (no safety data available)
What are the non-pharmacologic strategies available for the treatment of insect bites?
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
What are the pharmacologic options for treating insect bites and stings?
- 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)
