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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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