Insect Bites & Stings

Question 1

What happens when you get a spider bite

Answer 1

• venom is injected with bite
• most spiders are venomous, but few deliver enough for systemic symptoms
• venom from some is neurotoxic (widow spiders) to cytotoxic (reclusive spiders)

Question 2

what happens when you get a tick bite

Answer 2

• attaches and feeds until engorded with blood
• can attach to any part of body, but most often in warm areas that may be dificult to see (armpits, groin, scalp)
• may also attach to pets

*deer tick can cause lyme disease if attached for more than 36-48H

• others carry rocky mountain spotted fever and can transmit if attached fro 4-6 horus

Question 3

what happens when bitten by mosquito

Answer 3

• females inset tip of mouth into small bleed vessels near surface of skin and inj salivary secretions that cause local histamine reactions
• mosquitoes can carry number of viral and parasitic diseaess that may be transmitted when they bite

Question 4

what happens upon bee or wasp sting

Answer 4

• injected with venom
• honey bees can onyl sting once, bumble and vesipids (wasps) can string multiple times
• venom contains multiple proteins that can cause a severe reaction

Question 5

presentation of a spider bite

Answer 5

• Common reaction
  
  • itintial stinging then localized swelling, itching and inflammatio
• More severe raction
  
  • if black widow bite: pain within 30-60 min followed by sweating, nausea, blurred vision and muscle cramps
  • Brown reculse bite; redness, itching and pain within 6 hours; tissue necrosis if left untreated

Question 6

presentation of tick bite

Answer 6

• common presentation
  
  • red papule at bite site
    
    • swelling, blistering, bruising or itching may occur
• More severe reactions
  
  • Lyme disease
    
    • 3-30 days after bite -> erythema migrans rash that begins at bite site and expands gradually
    • flu like symptoms (fever, HA, fatigue, muscle and joitn aches, swollen lymph nodes etc)
    • Days to months after bite: severe headaches, facial palsy, severe joint pain, heart palpitations, inflammation of brain spainal chord
  • Rocky mountain spotted fever
    
    • Day 1-4: fever, headache, nausea and vomiting, myalia, rash 2-4 days after onset
    • Day 5+ altered mental status, coma ,acute resp distress

Question 7

presentation of mosquito bite

Answer 7

• common
  
  • rad, itchy papule that develops within hours and subsides voer a few days
• More severe
  
  • if develop antibodyies: large welts that last several days
  • West nile virus
    
    • flue like symptoms (fever, headache, body aches, swollen lymph nodes); possible rash
    • severe illness: high fever, stiff neck, confusion, muscle weakness or degeneration

Question 8

presentation of Bee or Vespid sting

Answer 8

• common
  
  • pain, redness and swelling at site within 4-48 horus
• severe
  
  • extensive local reaction: swelling over a large area (ie whole limb) that peaks at 48 hours and subsides over 3-10 days
  • systemic reaction: headache, fever, nausea, vomiting etc wtihin 12-24 hours
  • anaphylaxis: trouble breathing or swallowing, swelling of lips or throat, rapid HR

Question 9

red flags for insect bites

Answer 9

• sigsn fo anaphylactic reaction (trouble breathing or swallowing, swelling of lips or throat, rapid HR)
• experiencing a severe local rxn (significant paind and swelling beyond initial lesion) -> >10cm in diameter or history of severe rxn
• sting on tongue or mouth, or multiple stings
• bullseye appearance around lesion or appears infected (fever, pus or unusual swelling, redness or tenderness)
• immunocompromised
• lesion has persisted for >7days and not improving after 24h of treatment

Question 10

Non pharm strategies to manage insect bites

Answer 10

• remove the insect/stringer to decrease local reactoin
  
  • if tick, use tweezers and gasp close to head
  • remove stinger by gently scraping side with tweezers,ignernail or credit card
    
    • do not pull, can force more venom into skin
• clean bite with soap and warm water
• ice or cool to provide symptomatic relief and reduce swelling
• home remedies (oatmeal, baking soda baths, toothpaste, salat/vinegar) may relieve symptoms but are not well studies

Question 11

treating bug bites/stings with oral antihistamines

Answer 11

• recommend at self case dose to reduce itching, swelling and redness
• may be mroe effective than topical products in reducing pain, itching and ifnlammation associated with stings
• first and second generation are qually effective
  
  • second gen less sedating and longer acting
• avoid topical antihistamines due to risk of contact dermatitis

Question 12

oral analgestics for tick bites/stings

Answer 12

can be recommended at usual self care doses to decrease pain

Question 13

tpoical hydrocortisone for treatment of bites/stings

Answer 13

• can be applied up to QID for max 7 days to reduce itching, swelling and redness
• Topical hydrocortisone 0.5-1% is available without a prescription in Canada
• pharmacists may prescribe hydrocortisone 0.5-1%, but studies on efficacy are limited
• once or twice daily application of topical hydrocortisone may be as effective as TID or QID
• use cautiously on areas on broken skin and aovid if signs of infection

Question 14

what other products (besides hydrocortisone) are used for bites/stings

Answer 14

topical orudcts w/ local anesthetics:benzocains, pramoxine),

• astringents (calamine)
• counter irritants (menthol)

or ammonia/baking soda

*may get some relief but efficacy aidence is lacking

• in some patients may worsen symptoms due to irritation

Question 15

treatment of bties/stings with oral corticosteroids

Answer 15

• can be used for severe local reactions (prednisone 1 mg/kg (up to 50 mg) daily F5-7D
• pharmacists cant prescribe for this, so would need to reffer

Question 16

treatment of bug bites/stings in case of anaphylaxis

Answer 16

• epinephrine autoinjector
• seocnd dose may be needed 5-15 min if there was inadequate response with first dose

*never use oral antihistamines as first line treatment for anaphylaxis, but can be used as a secondary med to relieve hives and itching

Question 17

how can you prevent stings

Answer 17

• avoid areas wehre arthoropods can feel threatened (near nests or hives)
• usually sting in self defence
• wear clothes that cover as much as possible, time spent outdoors at dawn and dusk should be limtied

avoid acented perfumes that could attract them or sweet drinks

Question 18

prevention for tick/mosquito bites

Answer 18

• avoid tall gasses/swamps and standing sources of water (birdbaths, rain barrels)
• cover self and dont go out at dusk/dawm
• consider mosquito nets for hose under 6
• to prevent tick bites wear lighter clothed clothign to ticks mroe noticable
• wear clothes aht are tight at wrists/ankles
• consider permethrin impregnanted clothing
• use insect repellant

Question 19

using insect repellant

Answer 19

• deter biting in mosquitoes adn sticks but not stinging insects
• should contain Pest Control Product (PCP)
• dont apply to hands of children be could put hands in mouth

Question 20

Preferred regimen for self-managing localized skin reactions from arthropod bites & stings

Answer 20

Non-pharmacologic strategies ± oral antihistamine ± oral analgesic ± topical hydrocotisone 0.5–1%

Question 21

DEET as insect repellant

Answer 21

• proposed mechanism
  
  • offensive smell or taste
• general dosing
  
  • 6months - 2y: <10% applied 1d
  • 2-12: <10% applied up to TID
  • >12: 30% applied TID
• advere effects
  
  • skin irritation -> contact dermatitis
  • can be fatal if ingested
• other comments
  
  • dont use if under 6 motnhs
  • can be used in preg and breast feeding

Question 22

ICaridin

Answer 22

(Picaridin)

insect repellant

• Mechanism:
  
  • conceals attractants emitted by huamns ro changes insects abiltiy to smell them
• General Dosing
  
  • aply directly to skin
  • 10% Q5H up to QID
  • 20% Q7h up to BID
• Adverse Effects
  
  • rare
• Other Comments
  
  • not rec in children under 6 months unless traveling to high risk area
  • can be used in preg and breastfeeding

Question 23

Soybean oil

Answer 23

• Mechanism:
  
  • unknown, may conceal attractants emitted by humans
• General Dosing
  
  • apply to exposed skin PRN
• Adverse Effects
  
  • rate
• Other Comments
  
  • no age restriction
  • can be used in preg and breastfeeding

Question 24

PMD

Answer 24

• Mechanism:
  
  • Unknown; may conceal attractants emitted by humans
• General Dosing
  
  • Apply PRN, up to BID
• Adverse Effects
  
  • none known
• Other Comments
  
  • Not recommended for children <3y
  • Can be used in pregnancy and breastfeeding

Question 25

Citronella Oil

Answer 25

• Mechansim of action
  
  • offensive smell or taste to insects
• General Dosing
  
  • apply PRN to exposed skin
• Adverse Effects
  
  • skin irritation
• Other comments
  
  • req freq reapplicaiton
  • not recc for children <2
  • not recc in preg due to lack of data

Question 26

Metoflurthin

Answer 26

• Mechanism of action
  
  • releases as vapour to repell insects from area surroundign user
• general dosing
  
  • actiate clip on device prn
• adverse eff
  
  • skin and resp irritation
  • tremors and sympathatic activation if ingested
• other coments
  
  • no age restiction on use, childrne shoudl not handel
  • no safety data for use in preg
  • duraiton action is 12h/disk