Bites & stings Flashcards
What is the order Hymenoptera
Bees, wasps, hornets, ants –> 1/4 of anaphylaxis cases
Insect sting hypersensitivity is associated with what
Atopy
Mastocytosis
Exaggerated insect bites signifies what
Normal in children
Adults CLL, or rarely other haematologic malignancies
Hypersensitivity to mosquito bites with bullous and necrotic lesions occurs to who
Asians, Hispanics, adolescents and children with chronic EBV infection
Unusual reaction to insect bites - what should you do
Screen for haematologic malignancy and latent EBV, including in situ hybridization to detect EBV RNA
Rare complication of bee sting
Atrial arrhythmias
Killer bee and wasp attacks associated with what
Myoglobulinuria or haemoglobinuria and ANT
Beekeepers are at risk of what
Inflammatory arthritis –> chronic arthropathy
Dengue virus mosquitoes bite more in day or night
Day
Malaria virus mosquitoes bite more in day or night
Night
List of insect repellants
DEET - effective against wide range of arthropods, long hx of use, less proteciton in women Picaridin IR3535 p-Menthane-38 diol Botanicals: best evidence for neem oil
Safest level of DEET in children
Most products 10%
AA of paeds says as high as 30% fine over 2 months
Latin name for fire ant, and who is at risk of them
Solenopsis invicta
Electricians
Fire ant - how does it work
Venom increases membrane permeability causing histamine release from mast cells
Less concentrated in winter, so milder then
Grasps the skin with its mandibles, then pivots in a circular fashion forming a rosette pattern
Latin name for bed bug and what do they look like
Cimex lectularis most common, other is C hemipterus
Flattened oval body, segmented abdomen, retroverted labium, dorsal sclerotic plate, antennae with 4 segments
5-7 mm long, females slightly longer
C hemipterus is ~25% longer than lectularis
Triatomine bug: what does it transmit and what does it look like
Chagas disease - trypanosomiasis
1.503 cm in size, and have a tiger striped abdomen. Long antennae, thin and composed of 4 segments
Mouth is straight and has 3 segments
Behing head is a trianngular first segment of the thorax with a broad posterior base
Triatomine bug clinically
Kissing bug: bites face, particularly around lips Unilateral eyelid and periorbital swelling 1-2 weeks after conjunctival exposure to infected triatomine faeces - Romana sign in chagoma
Painless
Blister beetle: what does it use to keep eggs safe, and what would a biopsy look like
Cantharadin
Acantholysis with suprabasal keratinocytes
What do rove beetles cause and what have they been called before
Nairobi fly
Cause vesiculopustular eruption
Have narrow bodies 0.5-1.5 cm long, red-orange abdomen and short forewings
Dog flea
Ctenocephalides felis (the cat flea)
Human flea, what does it look like
Pulex irritans, a common dog flea in some locations
Has a single pair of hairs behind antennae
What does the Ctenocephalides flea look like
Two combs that resemble a mane of hair and a moustage: 2 ctenidia with a pronotal comb and genal comb
The felis has 6 hair bearing notches, the canis 8
What can stimulate fleas to hatch rapidly
Vibration
What do fleas serve as a vector for
Typhus, spotted fever, plaque, Bartonella henselae, tungiasis
Flea treatment
Lufenuron: oral and injectable - for animals
Lepidopterism
Caterpillar dermatitis - larval form of a butterfly or moth causes it. Often purely mechanical
Australia’s white stemmed gum moth – Chelepteryx collesi produces yellow discolouration of the skin
Can also cause ophthalmia nodosa: conjunctivitis etc
Which tick causes neurotoxins, after how many days and where is it usually found
Dermacentor tick, 4 days after attachment, commonly found in the Scalp
In Australia, which tick causes paralysis
Ixodes
Hard ticks transmit what
Lyme disease
Ehrlichiosis
Human granulocytic anaplasmosis
Rickettsia
How many legs do ticks have
Larval (seed) have 6 legs
Nymphs and adults have 8
What does the Ixodes scapularis tick look llike
8 legs
Females have a red thorax
Black legs
What does the Lone star tick look like (not in Aus)
(Amblyomma) White spot on back in females, male - pale ‘inverted horseshoe’ on posterior portion of dark scutum, and have hard dorsal plate
What have Amblyomma ticks been associated with in terms of allergy (not in Aus)
Allergy to beef, pork and lamb via development of IgE to galactose alpha 1,3 galactose –> urticaria/angioedema 3-5 hours after eating red meat
What does the rhipicephalus tick look like (in Australia)
Brown with brown legs, teardrop shape, hard dorsal plate
What is the paralysis tick in australia
Ixodes holocyclus
What do the Ixodes ticks look like
Small inornate brown cutum, large soft cream coloured engorged abdomen
Short anterior mouthpart
Prominent broad antennae
U shaped ventral groove with apex anterior to anus
(I think holocyclus just looks all brown)
Latin name for dust mite
Euroglyphus maynei
How to collect mites for microscopic examination
Clear with lactic acid or alctophenol (may take days), wash with water and mount on Hoyers medium
Alternatively just mount live or alcohol fixed mites in Hoyer’s medium or Live mites in Permount
What rash do mites cause
Papular, papulovesicular, bullous, urticarial, morbilliform
Chigger bites: lower legs, skin at edges of underwear, genital region
Clinical signs of Chigger bites
Intensely itchy, particularly in those sensitized
Grouped papules, vesicles or bulale on lower extremities where elastic meets skin
Summer penile syndrome: seasonal penile swelling, pruritis and dysuria seen in children wtih hypersensitivity
Latin name for red back spider + clinical features and treatment
Latrodectus hasselti
Skin: erythema, oedema, sweating and piloerection (secretes latrotoxins that act by depolarizing neurons), extra-c: painful mm spasms
Rx: benzos, IV calcium gluconate to prevent tetany, antivenin
Which funnel web spiders are endemic to Australia and what’s wrong with them
Tegenearia Hadronyche and Atrax: produce potent neurotoxins: pain, puncture marks, redness, bleeding, autonomic excitation: diaphoresis, hypersalivation, brady or tachycardia, hypertension and neuromuscular sx
Scorpion clinical manifestations and treatment
Pain out of proportion
Can get cardiorespiratory manifestations: cardiogenic shock, APO in those < 10 years (?must be renal excretion)
Antivenin and supportive care for rx
For minor: ice
What do centipedes clinically cause
Pain, erythema and oedema, and bleed ++ and paraesthesia
If ingested can be toxic
What do millipedes cause
Chemical ICF, can cause brownish skin discolouration
Clinical signs of bed bugs
Red-brown faecal staining and nit like ova on mattress seams
Pruritic, erythematous, oedematous papules, sometimes with a visible central haemorrhagic punctum
Clinical appearance and duration of lesions varies depending on individuals degree of sensitisation
Some individuals have little or no reaction to bedbug bites - so some family members are fine
Breakfast lunch and dinner
Wake up with new lesions, but can take several days to appear, latency tends to decrease with exposure
Does not transmit infections
Bed bug pathogenesis
Reaction results from immune response to salivary proteins
Bedbugs digest their meals very slowly, the blood in the bug’s gut remains relatively unclotted and is not membrane bound
Bed bug treatment
Eradication of bedbugs from infested homes is difficult: requires exterminators
Other: heating/seeaming, freezing, elimination of cracks and crevices
