envenom at ion edited

8/8/2019 Envenom at Ion Edited

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EnvenomationAdapted from source


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Introduction Envenomation is the syndrome of

symptoms as a result of the

introduction through the skin of avenom.

There are a huge number of

animals in the local area which can

cause envenomation.


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Topics of Discussion

Spider bites

Snake bites

venomous arthropods

Marine envenomation


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The Redback Spider

There was a Redback on the toilet seat when I was there last night.I didn't see him in the dark but, boy, I felt his bite.

The Redback on the Toilet Seat, Slim Newton, 1972.

The redback spider is one of Australia's most famous, or infamous, spiders. It

has earned this reputation through its widespread distribution and nasty bite.

More than 200 redback spider bites requiring antivenom are reported every

year. Contrary to Slim Newton's famous song, the female is generally the

offender.

As the redback's bite is potentially dangerous to humans, it pays to know a little

about this surprisingly common spider's habits and behaviour.


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Spider bites There are 34,000 species of spiders around the world,

almost all are fanged and venomous. Fortunately less

than 0.5% are able to penetrate human skin, and of

those, only a handful are dangerous.

Most bites occur when a spider is provoked or trapped.

Clinical features. Any bite can be painful and usually local swelling and

pruritis. Nausea, vomiting, sweating and dizzinesssometimes occurs. Severe allergic reactions are rare.

Significant bites give rise to broadly two syndromes

depending on the action of the venom.


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Necrotic arachnidisim

The site of the bite burns, swells and develops acharacteristic macular erythematous halo lesionwhich either resolves over a few days orbecomes purple. The purple area turns into adark eschar that sloughs off over a week,sometimes leaving a necrotic ulcer that can berecurrent and take months or years to heal.

Systemic involvement (also known as systemicloxoscelism, after the main causative species)

can

giv

e rise to fev

er, morbilliform rash, jaun

dice,intravascular haemolysis associated withspherocytosis, haemoglobinuria/renal failure,seizures and rarely DIC.


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Neurotoxic Arachnidism

Widow spiders (latrodectus spp)

Funnel-web (Atrax robustus)


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The initial bite can go unnoticed, be perceived as a

sharp pin prick (widows) or immediately painful

(funnel-web).

Local signs are usually mild.

In less than an hour there is a painful regional

lymphadenopathy, than headache, nausea, vomiting,

sweating, gooseflesh (horripilation), and painful muscle

spasms, especially of the legs and abdomen,

mimicking peritonism (lactrodectism).

Other features include tachycardia, HT, irritability,

psychosis, priapism, renal failure, respiratory

compromise and cardiac failure


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The active compounds of the

venoms.

Alpha-latrotoxin(widow) is a neurotoxin(mw 130,000). It opens cation channels (including

calcium channels) presynaptically, causing release

and then depletion of multiple neurotransmittersaffecting somatic and autonomic nerves. Nerve

terminals may also become rapidly disrupted and

engulfed by Schwann cells with re-innervation several

days later.


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Atratoxin (funnel-web) contains hyaluronidaseand other components (GABA, spermine, indole acetic

acid). Primates are particularly sensitive to the venom.

It causes acute massive release ofneurotransmitters

at autonomic and neuromuscular junctions with

associated uncontrolled auto

nomic hyper-reacti

vityand muscle twitching, followed about 2 hours later by

neurotransmitter depletion and weakness.


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Treatment First aid treatment depends on the spider.

With funnel-web and other rapidly acting venoms, firm crepe bandaging and

splinting of the bitten limb may delay venom spread.

For the redback use an ice pack.

Reassure the patient.

If possible bring the offending spider to the hospital to aid identification and

thereby treatment.

Supportive treatment for all bites includes analgesia (NSAIDS,opioids), tetanus prophylaxis, elevation and local wound care. Antihistamines,

benzodiazepines and atropine may also be useful for local and systemicsymptoms.

Antibiotics are not advocated unless there is evidence of secondary

infection


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Specific treatment.Antivenom is available for the red back and funnel-web from CSL

Side effects anaphylaxis, serum sickness.

Contraindicated in patients allergic to horses.

Neurotoxic arachnidism seems more responsive to antivenom than does the

necrotic type.

Calcium gluconate (10ml of a 10% solution given slowly iv) relies the pain of

muscle spasms caused by Latrodectus venom rapidly and more effectively than

muscle relaxants such as diazepam.Other therapies have been advocated from in-vitro studies such as dapsone,

hyperbaric oxygen, corticosteriods and surgical excision fornecrotic lesions,

but there is little clear evidence of their effectiveness.


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P

rognosisAntivenom has dramatically cut the mortality and almost no deaths now occur

where it is available.

Most fatalities are in children and the elderly . Death from redback bites is

essentially unheard ofnow, and those reported to have been attributable to

redback bites in the past are now thought to be dubious.

Deaths are likely to be related to the faster acting potent venoms, funnel-web

bites can lead to death in about 2 hours.


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Discharge Criteria from A&E asymptomatic patients, with no positive identification can be

released after 1-2 observation.

Asymptomatic patients with no comorbid illness, with a positiveidentification should be observed for minimum of 4-6 hours and

discharged if their condition is unchanged(not always possible ).

All discharged patients must be instructed what to watch out for in the

way of symptoms and to seek appropriate follow up.

THE CSLANTIVENOMFOR REDBACK BITES ISEFFECTIVE UP TO 3 WEEKS POST BITE FOR

PERSISTANT SYMPTOMS


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Snake bitesAbout 3000 people are bitten each year, of whom 200

will receive antivenom, fatality rate between 1.8-3.7/year.

Half of all snake bite deaths are caused by brown

snakes.Are there many deaths from snakebite in Queensland?

All snakes attempt to avoid biting humans, but many will

do so in defence if they are deliberately provoked or

accidentally disturbed. Even though snakebite happensregularly, death from such an event is rare in Queensland

and in the rest of Australia. This seems to be a puzzle, given

that more than a few Queensland snakes have extremely

toxic venoms and that many live on the coast, where most

people live.


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There is an explanation. Most snakebites in Queensland are

from land-dwelling snakes that are not potentially

dangerous. These are the majority of our snake species.Queenslanders tend to be aware and wary of all snakes.

They know to leave snakes alone wherever possible. The

tried, tested and effective methods offirst aid and medical

treatment following snakebite appear to be well known and

readily available.

It is usually easy to avoid being bitten. Most bites occur

when people attempt to taunt, catch or kill snakes. 75% of

bites are to the upperlimb.

Snakes will always give an 'aggressor' a chance to retreat.

Several potentially dangerous species adopt characteristic

defensive postures.


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Eastern BrownSnakes 'stand up' in a distinctive 'S' position

and strike repeatedly. However, some species give little

warning before biting and then movement from defensive

posture to a warning or full bite can take place rapidly,sometimes with little provocation.

Black snakes flatten the heads and hiss and feint frantically.

Bandy Bandy will raise its black and white ringed body into

vertical loops, sometimes thrashing about.

a Brown Tree Snake will 'stand up', hiss and feint,

sometimes with mouth agape;

Blind snakes are non-venomous, but can emit a strongodour from special glands. The message about how to

avoid being bitten by snakes is clear. Always leave

snakes alone.


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Snake venomSnake venom is used mainly to immobilise, or kill and begin digesting prey.

Its use in defence is secondary.

Most of the snakes in Queensland are venomous.

About 20 of these are regarded as potentially dangerous, because they

have highly toxic venoms.

What sorts of venoms do snakes have?

Neurotoxins affecting peripheral nervous system, causing drowsiness,

paralysis and difficulty breathing. (tiger snake, taipan, and death adder)

Myotoxins destroy muscle tissue, causing weakness, and kidneymalfunction secondary to rhabdomyolysis or direct renal toxicity with the

brown snake

Haemotoxins affect the blood by increasing clotting or bleeding (brown

snake, tiger snake and taipan)


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Clinical presentation and symptoms

The actual bite may include pain, swelling or bruising around the bite, patientsmay only describe the sensation of being punched.

The myriad of symptoms include, nausea, vomiting, headache, diplopia,

dysphonia, progressive muscle weakness, discolouration of urine, collapse, and

seizures.

First Aid.

Aim is to delay absorption of the venom from the bite site until the patient is in a

facility capable of administering antivenom.

Pressure immobilisation and splinting to prevent passage of the venom via thelymphatics

Immobilisation of the whole individual, walking or moving affected limbs even

after pressure immobilisation of the bitten limb has been shown to hasten

absorption into the lymphatics


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The critters involved. ( In order of potential danger )

1 Western Taipan

2 Coastal Taipan

3 Tiger snake

4 Common orEastern Brown

5 Mulga or King Brown


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6 Common Death Adder

7 Northern Death Adder

8 Desert Death Adder

9 Western Brown

10 Colletts black snake

11 Red-bellied black

12 Spotted or

Blue-bellied black

13 Small eyed snake


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14 Rough-scaled snake

15 Speckled-brown

16 Stephens banded

snake

17 Pale-headed snake


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Management of snake bites

Pressure immobilisation of affected limb or pressure to the trunk

firmly so not as to interfere with respiratory effort.

If patient deteriorates once bandage removed, it should be

reapplied immediately.

The Commonwealth Serum Laboratory (CSL) Snake Venom

detection Kit (SVDK) detects venom at the bite site or in the

urine, and identifies the snake involved.

Positive SVDK is not an indication for antivenom therapywithout evidence of systemic venom effect.


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Pressure immobilisation.


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Management (cont)

Clinical indications for immediate administration of antivenom include:

i. Vomiting, severe headache.

ii. Neurotoxic effects such as ptosis, cranial nerve involvement, progressive

muscle weakness or diaphragmatic involvement.

iii. Evidence of coagulopathy.

Investigations FBC, U&Es, CK, urinalysis looking for evidence of haematuria

or myoglobinuria. Coagulation studies, if PT or APTT are prolonged then

Fibrin degradation products should be obtained (D-Dimer).

In the absence of clinical or laboratory evidence ofvenom effect, the elastic

pressure bandage may be removed and the patient observed.

If significant envenomation has occurred most patients will develop clinical

or laboratory evidence of envenomation within 2 hours of removing thebandage. Coagulation studies should then be repeated 2 hours post

bandage removal.


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Antivenom for snake bites.

CSL BROWN SNAKE ANTIVENOM

CSL TIGER SNAKE ANTIVENOM

CSL BLACK SNAKE ANTIVENOMCSL DEATH ADDER ANTIVENOM

CSL TAIPAN ANTIVENOM

CSL POLYVALENT SNAKE ANTIVENOM

Same dose for adult and child


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SDVK


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The general principle of the SVDK

This only applies for suspected snakebite (in Australia). The CSL Snake Venom

Detection Kit (SVDK) is produced specifically to identify the presence and type ofAustralian snake venom. It is very practical in design, giving results which relate directly

to the most appropriate antivenom to use.The best sample for testing is a swab from the

bite site and it can detect nanogram quantities ofvenom. Even a bite site that has been

washed may yield a positive result.

Venom may be present in the urine if the patient has systemic envenomation. This is

then a useful alternative sample.Unfortunately, because ofnon specific binding with plasma proteins, blood is not a

reliable sample. Both false positives and negatives are possible using blood and it is

therefore not recommended to use the SVDK on blood.

Everything needed to perform a SVDK is provided in the kit, with the following

exceptions. The kit does not provide a source of running water for the washing phase,

nor a container for waste. If the kit is to be used in transit in a medical retrieval plane orambulance, then squeeze bottle of water for washing and a waste liquid container is

required.

Each SVDK box contains three test kits and three sample bottles, but the substrate

reagents and sample well holder are common to all 3 test kits.


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How to perform the SVDK test

Locate the bite site (cut the bandage over the bite site only to gain access, if there is

first aid in place). Ensure the site is not washed. Test urine f there is obvious systemic

envenomation has occurred and the bite site is of poor quality.

Use a single cotton bud swab stick provided in the kit and an unused "Sample

Diluent" bottle. Unscrew the cap off the bottle, revealing the dropper cap. Lever this

off, using a fingernail and put it to one side.

Put the swab stick into the sample diluent fluid and thoroughly moisten.

Rotate and rub the moistened swab stick vigorously over the bite site and adjacent

skin, to pick up venom on the skin around the bite and from just beneath the surfaceof the bite marks.

Place the swab stick back in the "Sample Diluent" bottle and twirl it around, to get

any venom off into solution. Remove the swab stick and replace the dropper cap.

Open a pack containing test wells (silver pack); remove the enclosed set of 8 joined

wells and place them in the holder. There is a lug at one end to enable easy

placement in the right orientation. Remove the cover from the wells. Place the requisite number of drops of the sample diluent you have prepared into

each well (currently 2 drops in each well).

Allow to stand for 10 minutes.


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Wash all wells under gently running water 7 times (15 times if blood used as

sample), then invert and gently shake out excess water(don't dry the inside of

the wells with anything).

Add the 2 substrate reagents (currently one drop to each well of the "Peroxide"

and the "ChromogenSubstrate").

Allow to incubate for 10 minutes, observing against a white background for

colour change. It is vital to observe the kit throughout this final phase, as the

time sequence of colour change may be crucial.

A blue colour should develop in well 7 (positive control), usually within 2-3minutes. There should be no colour change in well 6 (negative control). A colour

change in any of wells 1 to 5 indicates the presence of snake venom. The

number of the well changing colour first indicates the type of snake venom and

corresponding CSL snake antivenom. If there is no snake venom detected, then

wells 1 to 5 will not change colour.

Place the common reagent tubes, the white well holder, instructions, unusedswab sticks and well packets back in the box. Replace in the fridge. The

reagents will deteriorate quickly if left out at room temperature too long!


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A positive result forvenom from the bite site does not mean the patient has been

significantly envenomed. A positive SVDK from the bite site is not an indication to give

antivenom. It is an indication of the type of antivenom to give if, on clinical or laboratory

grounds, the patient needs antivenom therapy.

Well 6 must not change colour and well 7 must change to blue for the test to bevalid.

Wells 1 to 5 show no colour change - no venom has been detected.

Well 1 changes to blue first - tiger snake or rough scaled snake, or possibly a

copperhead. (CSL TigerSnake Antivenom)

Well 2 changes to blue first - brown snake. (CSL BrownSnake Antivenom)

Well 3 changes to blue first - mulga snake (king brown), red bellied black snake,spotted black snake or Collett's snake. All these respond to CSL Black Snake

Antivenom, but this is best reserved for bites by the mulga snake, as all the others

respond well to CSL TigerSnake Antivenom (which is lowervolume and much cheaper).

Well 4 changes to blue first, then the patient has been bitten by a death adder, and

CSL Death Adder Antivenom will be the most appropriate choice.

Well 5 changes to blue first - taipan or inland taipan(CSL Taipan Antivenom orCSLPolyvalent Antivenom)

Wells 1 and 3 change to blue at the same time - either a copperhead, a red bellied

black snake, a spotted black snake or a Collett's snake. (CSL TigerSnake Antivenom)

Note: Sea snake venoms are not reliably detected by the SVDK.


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Polyvalent antivenomMonovalent antivenom not available.

The SVDK is not available or has not identified the type of snake and

the range of possible snakes would require the mixing of three or

more monovalent antivenoms.

Severe envenomation and insufficient time to wait on the SVDK and

the range of possible snakes would require the mixing of three or

more monovalent antivenoms.

Stocks of appropriate mon

ovale

nt ha

ve bee

nexhausted a

nd thepatient requires further therapy with antivenom


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Side effects of the Antivenom

Anaphylaxis is very rare complication in Australia,

however treatment should be administered in a

setting where anaphylaxis can be managed.

Can be reduced with premedication, suggested

subcutaneous adrenaline 0.3ml 1:1000 adult and

0.1ml in children and a parenteral antihistamine.

Premedication with corticosteriods may have a role

in preventing acute serum sickness, plus a 5 day

course post antivenom


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Venomous Arthropods.

Bees and Wasps.

Stinging ants (Jumper and Bull ants).

Fire ants

Australian

Paralysis Tick.Scorpions.

Centipedes.

Caterpillars.

Beetles.


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Bees and Wasps.

The Honey bee (Apis mellifera), the European Wasp

(Vespula germanica), native wasps (Polistes sp.) and

ants from the genusMyrmecia are important causes of

mortality and morbidity.

Often the sting causes a painfullocal reaction with

little systemic effect. In sensitized individuals stings

can cause severe local and/or generalized allergic

reactions, including anaphylaxis.

Dose-dependent toxicity can sometimes be significantwith multiple bee and European wasp

stings. Haemolysis, rhabdomyolysis and metabolic

derangement may precede clinical deterioration.


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First aid

First Aid and Medical Treatment

In all cases, bee stings should be scraped off, not pulled off, as this may

cause further injection ofvenom from the venom gland which remains

attached to the sting.

Innon-allergic persons iced water usually relieves the pain of local

reactions. Antihistamines should be considered for significant itch. Treatment

of toxicity due to massive envenomation includes supportive care and close

laboratory monitoring.

In allergic patients, the pressure-immobilisation procedure should be used

and medical care sought immediately. Patients who have suffered severe

reactions should always have access to injectable adrenaline and know how

to use it. Oral and topical steroids may be useful for managing large local

reactions. Purified venoms are available for use in immunotherapy for theHoney Bee, EuropeanWasp and some paper wasps.

International experience suggests immunotherapy may have an efficacy of up

to 98%.


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Stinging Ants.Some species of ants possess a sting and venom gland in their tails, as wellas powerful jaws. The ant bites with its jaws, then doubles up to inject

venom via the sting, usually resulting in local pain or itch, with a weal or

swelling at the site. Although only local problems typically result from

envenomation, patients allergic to the venom may suffer life-threatening

reactions. Stinging ants of the genus Myrmecia (jumper ants and bull ants)

represent a hazard in the southern states of Australia due to the relativelyhigh proportion of the population(3-4% estimated from one study) with

significant allergy to the venom of these creatures. Purified venom for

desensitisation is currently unavailable, but AVRU is assisting researchers of

the Molecular Immunology Group at the Kolling Institute of Medical

Research at Sydney's Royal North Shore Hospital in the preparation of a

product that may be used in the future in the treatment of these allergicpatients.


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Fire Ants.These aggressive ant species can inflict a painful sting, injecting

venom that causes a burning sensation and subsequent blistering

(hence their name). An individual ant can sting multiple times, and

sting sites may develop pustules and secondary infection. As is the

case with jumper ants and bull ants, some people may also suffer

potentially life threatening allergic reactions to the venom. They

may attack farm and domestic animals and can destroy some p

lantsand crops. Mature nests may contain as many as 200,000

individuals.

These ants have caused significant ecological and economic

problems in areas where they have become established, such as

the United States, South-East Asia and the Pacific islands of Guam

and Okinawa.

Two species of fire ants have been identified in Australia. Thetropical fire ant, Solenopsis germinata, is found in the Northern

Territory, where it has become established in coastal areas, but has

not as yet resulted in significant problems. Late in February 2001,

the South American fire ant (Solenopsis invicta.) was identified in

southern Queensland around Brisbane's south west.


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CLINICAL FEATURES

Significant illness is more common in children, and may present as difficulty

walking or generallethargy, progressing to problems with swallowing and

limb or genera

lised weakness.Older children and adults may present with double or blurred vision followed

by progressive weakness and paralysis.

Occasionally, paralysis is localised, e.g. Bell's palsy.

Tick envenomation should be considered in the differential diagnosis of

progressive paralysis in all patients who have been in tick-infested areas.

First aidFirst aid consists of finding and removing the tick, and supporting the patient

until antivenom can be administered. The tick should be levered out using a

pair of curved scissors. If the patient is already ill, the pressure-

immobilisation procedure should be used if possible to inhibit the movement

of any toxic saliva which has been expressed during the removal of the tick.

NB. Check carefully for other attached ticks.

Medical Treatment and administration ofAntivenomSupportive care, including supplemental oxygen and occasionally

mechanical ventilation may be required.

Less severe cases may only require removal of the tick and observation, as

symptoms will not necessarily abate after its removal. For severe cases, tick

antivenom may be given intravenously.


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Scorpions.Scorpions are distributed throughout Australia, tending to be

larger in the warmernorthern areas. On a world scale,Australian scorpions are relatively innocuous, with very few

deaths reliably documented as related to scorpion

stings. Local pain and swelling are the major clinical problems

following Australian scorpion stings. First aid consists of the

application of iced water and analgesia if required. The

scorpions of central and south America and Africa are muchmore dangerous, with thousands of fatalities and serious

illnesses occurring every year in these areas in relation to

scorpion envenomation.

First Aid forScorpion stings

On a world scale, Australian scorpions are relativelyinnocuous, with very few deaths reliably documented as

related to scorpion stings. Local pain and swelling are the

major clinical problems following Australian scorpion

stings. First aid consists of the application of iced water and

analgesia if required.


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Centipedes and Millipedes

Centipedes are found throughout Australia, and the rest of the world, and are common in

urban gardens. Bites may be painful, especially those inflicted by the largernorthern

species. The venom is usually associated with only local effects, but systemic illness, and

even death, have been reported, although no fatalities have been recorded in Australia. No

specific first aid treatment is recommended beyond the application of ice water or packs for

local symptom relief.Millipedes may exude alkaloid-containing haemolymph from their joints when

threatened. This may be irritant to the skin and cause skin lesions, often in characteristic

circular shapes.


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Beetles.Many Australian and overseas beetles produce toxic or irritant

substances invenom, saliva or haemolymph. Allergy to these

substances may cause problems for individual patients, who may

require treatment with antihistamines or even adrenaline in severe

cases. Irritant substances are common, and local pain or itch may

be relieved by the application of ice packs or iced water. Whiplashrove beetles (Paederus sp.) are particularly associated with severe

exfoliative dermatitis.

First Aid for Beetle envenomations

No specific first aid treatment is required for bites, stings or skin

irritations caused by Australian beetles. Local symptoms of pain

and itch may be relieved by the application of ice packs or icedwater. Allergy is possible to irritant substances produced by

beetles. There is no product currently available for desensitisation

to these substances.


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Marine Envenomations. Sea snakes.

Fish stings.

Stingrays.

Stonefish.

Jellyfish. Box jelly fish (Chironex fleckeri)

and Irukanji syndrome.

Cone shells.

Blue-ringed octopus.


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Sea Snakes.The sea snake venom is 2-4x more toxic

than that of the cobra.

Tend to deliver less venom.

bite size contrary to popular belief can be

wide enough to swallow a whole fish.

One in four bitten ever show signs of

envenomation.

Reluctant to inject venom even when they dobite.

Sea snake venom is Neurotoxic


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Clinical Features.

An initial puncture at the time of biting is noted.Fang and teeth marks may vary from 1 to 20, but usually 4.

Teeth may remain in the wound.

Latent asymptomatic period, 10 mins to several hours.

Mild symptoms include euphoria, anxiety, restlessness.

The tongue may feel thick, thirst, dry throat, nausea and

vomiting occasionally develops.

Generalised weakness, may progress into

paralysis.

Paralysis either ascen

din

g Guillain

-Barretype or extends centrally from bite site.

Cardiac failure, convulsions and coma can

be pre-terminal events

Myoglobinuria and its complications ARF.

When recovery occurs it is usually rapid.


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First Aid and Treatment Sea snake bites

Pressure Immobilisation.

Treatment maybe be required for cardiovascular shock,

convulsions.Ooften assisted ventilation is required.

Fluid and electrolyte disturbances, high potassium, and

haemodialysis.

Acute renal tubularnecrosis and myonecrosis areconsidered temporary.

Sea snake antivenom from CSL is available - composed of

2 antivenoms each of specific action - covers most common

sea snakes.

Occasionally ineffective - may require a land based snake

antivenom. The TigerSnake antivenom is preferred.Polyvalent snake antivenom can be used, although its value

is yet to be determined.

Hospital admission for 24 hrs post bite as symptoms may

be delayed.


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Fish Stings.Many fish have spines and venom apparatus usually for protection.

Occasional deaths have been ascribed to the following:Scorpion fish

Fire fish

Catfish

StargazersRabbitfish (happy moments)


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Clinical features of fish stings

Local pain

Excruciating over the next few minutes

Lessens after a few hours.

The puncture wound is anaesthetized, and the surrounding tissue

hypersensitive.

Pain and tenderness in the regional lymph glands may extend

centrally.

Locally appearance of a puncture wound, one or more with an

inflamed and sometimes cyanotic zone around this.Surrounding area becomes swollen, pale, and pitting oedema.

Generalised symptoms include malaise, nausea, vomiting and

sweating, mild temperature elevation and leukocytosis.


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First Aid and treatment of fish stings

Immerse the wound in hot water( up to 45 C) for 30-90 minutes, or

until the painno longer recurs.

Clean and wash the wound.

Fisherman often make a small incision across the wound and

parallel to the long axis of the limb, to encourage mild bleeding

Local anaesthetic 5-10mg 2% lignocaine, without adrenaline.

Removal of broken spines, exploration of the wound.

Topical antibiotic ointment

Tetanus prophylaxis

Analgesia

For small retained spines, foreign bodies or bone injury systemic

doxycyline may be needed.


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Stonefish.

Grows to about 30cm in length and liesdormant in shallow waters buried in sand, mud,

coral or rocks.

13 dorsal spines capable of penetrating a sand

shoe.

When

pressure is applied over them twovenom glands discharge along ducts to each

spine into the penetrating wound.

The fish can live for hours out of the water.

The venom is an unstable protein - pH of 6.0.

Molecular weight of 150 000 Da.

Produces intense vasoconstriction, andtherefore tends to be localised.

Destroyed by heat, alkalis and acids.


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The toxin is a myotoxin acts on skeletal, involuntary and cardiac muscles

blocking conduction in these tissues.

This results in muscular paralysis, respiratory depression, peripheral

vasodilatation, shock and cardiac arrest.

Each spine has 5-10mg venom associated with it and is said to be

neutralised by 1ml of antivenom from CSL.


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Clinical features of stonefish envenomationImmediate pain, increasing in severity over 10 minutes.

Excruciating in severity sufficient to cause unconsciousness in some.

Ischaemia of the area is followed by cyanosis.

The area becomes swollen and oedematous, often hot with numbness in the

centre and extreme tenderness around the periphery.Paralysis of the adjacent muscles is said to immobilise the limb as may pain.

Signs of mild cardiopulmonary collapse are not uncommon, with pallor, sweating,

hypotension, and syncope.

Bradycardia and cardiac dysrhythmias and arrest are possible.

Malaise, exhaustion, fever and shivering may progress to delirium,

incoordination, generalised paralysis, convulsions and death.

Convalescence may take many months and be characterised by periods of

malaise and nausea.


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Treatment of stonefish envenomation

Initially same as fish sting first aid.

Stonefish antivenom may be administered.

Initially 2mls of antivenom is given IM (IV route in

severe envenomation).

Further doses given if required

Should never be given to people with a horse allergy

A stonefish sting is said to confer some degree of

immunity for future episodes.


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Stingrays

Stingray spine when penetrating the body ruptures an

integument over the serrated spine and venom escapes and

passes along grooves into the wound.

Extraction of the spine results in a deep laceration due to the

serrations and retropointed barbs, it may even leave the

spine or sheath within the wound.

NB often double spines.


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Stingray venom

Proteinvenom molecular weight >100 000.

Heat labile, water soluble

Intravenous lethal dose 28mg/Kg of body weight

Low concentrations cause ECG effects of prolonged PR interval

and bradycardia.First degree atrioventricular block may occur with mild

hypotension.

Larger doses cause vasoconstriction, 2nd and 3rd degree HB and

signs of cardiac ishaemia.

Most cardiac changes are reversible in the first 24 hours.Some degree of respiratory depression is noted with larger

doses ofvenom thought to be due to the neurotoxic effect on the

medullary centres.


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Clinical features ofStingray envenomation

Local

Pain is the dominant feature increasing over 1-2 hrs; easing after 6-10 hrs.

Aggravation of pain within days is usually due to secondary infection.Bleeding may be profuse and actually relieve pain.

A mucoid secretion may follow from the wound.

The area is swollen and pale with a bluish rim, centimetres in width

spreading around the wound over the first 1-2 hours.

General

Anorexia, nausea, vomiting, diarrhoea, frequent micturition and salivation.Extension of pain up the lymphatic drainage to regional pain.

Muscular cramp, tremor and tonic paralysis may occur in the affected limb.

Cardiac and respiratory as noted earlier.

Nocturnal pyrexia with copious sweating, nervousness, confusion or

delerium

Fatalities are possible especially if the spine perforates the pericardial,

peritoneal, pleural cavities.

Death may be due to envenomation, trauma haemorrhage, or delayed

tissue necrosis and infection.


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Treatment of stingray injuries

Same as for fish stings.

Special problems of body cavity penetration,

with immediate and delayed haemorrhage.

Patients must be observed as delayed

problems frequently occur.


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Jellyfish


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Boxjelly fish ( Chironex fleckeri )

Chironex are reputed to be the most

venomous marine animal known.

It is especially dangerous to children and

patients with cardiorespiratory disorders.

Its box-shaped body can measure 20cm,

and it has up to 15 tentacles up to 3 metres

long.

It increases in size during the HOT season

for mating and increases in toxicity.

The severity of the sting increases in with

the extent of contact with the skin, as little

as 6-7m can kill

Stinging can occur through surgical

gloves!


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Box stings


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The box toxin

The venom is made up from a lethal combination of

dermatonecrotic and haemolytic fractions with specific antigens.

Cross immunity probably does not develop to other species

Initial cardiovascular response is a rise in the BP, followed by

oscillations between hypo- and hypertension.Hypotensive episodes are related to bradycardia, cardiac

irregularities especially delay in AV conduction and apnoea

Hypertensive effects are due to cardiotoxicity, baroreceptor

stimulation and/or brain/brainstem depression.

VF or asystole will precede cerebral death


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Clinical features of box

Excruciating pain, patient usually screams on contact with the box.

Clawing at adherant tentecales

Pain comes in increasing waves of intensity

Patient may become confused, act irrationally or lose

consciousness and drown because of this.

Local

Red, purple, brown whiplash line 0.5cm wide develop within

seconds.

Beaded or ladder pattern

If the patient survives the initial shock large weals develop and

after 7-10 days necrosis and ulceration develop over the area of

contact

Itching may be troublesome and recurrant.

Pigmentation and scarring may be permanent


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General

Cardiovascular collapse and shock is common.

Respiratory distress

Paralysis

Abdominal pain

Malaise and restlessness may persist

Physical convalescence requiring up to a week.

Immunity is said to be conferred following repeated and recent

contacts


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Treatment of box stings

Copious amounts ofvinegar to reducethe further discharge of more nematocyts

Remove tentacles carefully

CPR ifnecessary

Antivenom if available.

Application of topical LA.

Further ALTSIntravenous narcotics orGeneral

anaesthesia.

Steroids? 100mg hydrocortisone 2 IV

ICU admission mandatory


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Cone Shells

Cone shell venom causes skeletal muscle paresis or paralysis, with or

without myalgia


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