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Venoms, poisons, infections & allergies
‘Arty’. To me the word's got as much venom associated with it as 'wacky'. Alex Kapranos
Venoms, poisons, infections and allergies all have unique meanings, but are often confused in everyday language. Let’s break them down to understand what they actually mean.
VENOMS and POISONS
According to the Oxford English dictionary:
A venom is a poisonous substance secreted by animals such as snakes, spiders, and scorpions and typically injected into prey or aggressors by biting or stinging.
A poison is a substance that is capable of causing the illness or death of a living organism when introduced or absorbed.
So basically, if you bite it and die, it is poisonous; if it bites you and you die, it is venomous. Venomous creatures actively inject chemical toxins via fangs, spines, stingers, or similar, into their victim. Venom is used by animals either as a defence mechanism, to counter an attack by an often larger animal, or as a way of catching prey. In some cases, the lethality of the venom is absurd: for instance, just a single drop of the inland taipan’s venom can kill about 100 adult humans. Venom is typically stored in specialised glands inside the venomous animal’s body, and in some cases is used to aid digestion of prey.
By comparison, poisonous animals secrete harmful chemicals, but are only transmitted to their victim if the victim eats or touches the poisonous plant or animal. Similar to venomous animals, even extremely small poisonous critters can have an enormous impact. For instance, the posion dart frog only measures 2 inches but has enough skin toxins to kill about 10 adult humans.
Poisonous substances and venom generally work by disrupting some kind of biological function of their prey or victim. Three of the most common types are neurotoxins, hemotoxins and cytotoxins.
- Neurotoxins affect the nervous system with the main aim of killing by paralysing the heart and/or lungs. Signs and symptoms include suppressed heart function and breathing, as well as vomiting, paralysis, convulsions and muscle cramps. Critters that use neurotoxins include scorpions, paralysis ticks and cobra snakes.
- Haemotoxin/hemotoxins affect the blood and tissues of the body and has the ability to break down blood cells and body tissues. Signs and symptoms include severe internal bleeding, major organ failure and the seeping of blood from body orifices such as the ears, nose and eyes. Critters that use hemotoxins include vipers and pit vipers.
- Cytotoxins cause spontaneous death of the body cells and severe damage to body organs. Signs and symptoms include excruciating pain and major swelling of body tissues. Some jellyfish use cytotoxins.
Our skin is an extremely effective barrier to infectious agents such as bacteria. However, if the skin is pierced through an injury, scratch or bite, the wound is susceptible to infection. Ordinarily, germs like bacteria and viruses live on our skin without causing trouble but if the skin becomes broken, these germs move into the more sensitive tissues underneath and can start to multiply and spread, leading to an infection. Infected wounds left untreated can spread and quickly become a serious medical condition.
Any animal attack like a bite or a sting where the skin has been broken has the potential to become infected, and must be treated with this in mind. Having said that, if there is any risk at all that the bite is venomous (e.g. an unidentified snake or spider), then treating the patient for venom is the priority, and any infection risks are considered secondary.
Bites from some mammalian species carry the risk of transfer of infectious diseases like tetanus, Hep B from human bites and Australian bat lyssavirus (ABLV) from bats, and appropriate medical follow up must be taken.
With any type of bite or sting there is the potential for an allergic reaction. An allergic reaction is the body’s response to an invading substance. Our immune system gets activated when it detects foreign objects, and mobilises resources (including white blood cells) to the area to cope. In some cases, our bodies get this wrong, and overreacts. It can be from something that does not normally upset other people, but often people with allergic reactions don’t know they are allergic until they are affected.
There are two stages to developing an allergy. The first stage is sensitisation, where the allergen is recognised by the immune system and antibodies are made to fight it (even though the allergen is harmless).
The second stage is when the allergic reaction kicks in. Since the immune system retains the memory of the allergen, whenever it has contact with that allergen again even in the tiniest quantity, the body responds. That’s why people with hay fever have coughs, runny nose and flu-like symptoms at pollen season, or the tiniest amount of peanuts in food can affect someone with a peanut allergy.
Allergic reactions can occur after a bite or sting, where the body overreacts to any new substances that have been detected, be that a poisonous substance from a venomous creature or an infectious germ after the skin has been broken.
The main difference between an irritation like small swelling from a mosquito bite and an allergic reaction like hayfever is that an irritation is localised to the affected area. By comparison, an allergic reaction spreads to other parts of the body.
Anaphylaxis is a severe allergic reaction where the patient experiences extreme allergic responses including itching, swelling and shortness of breath. Anaphylaxis must be treated immediately, as it can cause death if untreated.
FUN FACT: Did you know that our cute and cuddly Platypus (Ornithorhynchus anatinus) is armed with venomous spurs?
Male platypus have a sharp barb located above its rear webbed feet. Used mainly during the mating season, males inject painful venom into their rivals during a fight.
Reports of humans being stung by platypus are rare, but do exist. While not fatal, stings are reported to be extremely painful with the potential to cause permanent disability around the affected area. Interestingly, individuals held in captivity do not produce venom, making it challenging for scientists to collect and reliably test the properties of platypus venom reliability.
So don’t be fooled by it’s cute and cuddly appearance, male platypus are venomous! As with all animals you see on a bushwalk, respect them from a distance and leave no trace.
Managing venomous bites
I don't use a pen. I write with a goose quill dipped in venom. Jay Dratler
Venomous bites have the potential to be life threatening and must be taken seriously until proven otherwise, either through a positive ID of the animal being non-venomous, or confirming that the attack was a ‘dry bite’.
Dry bites are bites by venomous animals where no venom was released (i.e. a bite without envenomation). It’s actually quite common in some species. For example, 80% of the time, Australian eastern brown snakes (Pseudonaja textilis) inflict dry bites [note]Dart, Richard C. (2004). Medical Toxicology. Lippincott Williams & Wilkins. p. 1551. ISBN 978-0-7817-2845-4.[/note]. By comparison taipans inflict dry bites only 5% of the time [note]Dart, Richard C. (2004). Medical Toxicology. Lippincott Williams & Wilkins. p. 1551. ISBN 978-0-7817-2845-4.[/note]
In practice, determining whether or not the bite was a dry-bite is extremely challenging. That’s why we always treat bites as venomous in the bush just in case.
Read through the following posts for more specific information on venomous critter bites and how to manage them.
A practical guide to useful first aid techniques to deal with bites and stings
There are four techniques that are used to manage bites and stings: pressure immobilisation, ice pack, hot water and vinegar. Each are specific to the type of species that the bite/sting came from, but in all cases we follow DRSABCD, first making sure that the patient and other people in the group are safe.
If you know what animal bit or stung the patient, follow procedures specific to that animal group. Use this Quick and easy table of reference from St John Ambulance to work out the technique to use:
|Pressure bandage with immobilise||Funnel-web and Mouse spiders, snakes, Blue-ringed octopus, coneshells and sea snakes||1. Follow DRSABCD.
2. Calm patient and keep still.
3. Apply a crepe bandage over bite site.
4. Firmly apply a heavy crepe pressure bandage, starting at the fingers/toes and working up as far as possible.
5. Immobilise the bandaged limb using splints.
6. Ensure 000 has been called or emergency beacon activated.
|Ice pack (cold compress)||Red-back spiders (and others not mentioned above), bees, European wasps, ants, ticks, scorpions, centipedes||1. Follow DRSABCD.
2. Calm patient and keep still.
3. Apply an ice pack directly over the bite site to relieve the pain.
4. Seek medical attention if necessary
|Hot water||Blue-bottle (Pacific Man-O-War) jellyfish, Bullrout fish, Catfish, Crown-of-Thorns starfish, Stingray, Stonefish and nontropical minor jellyfish||1. Follow DRSABCD.
2. Calm patient.
3. Place patient’s stung limb in hot water (as hot as you, the first aider, can tolerate).
4. Ensure 000 has been called or emergency beacon activated.
|Vinegar||Box, Irukandji and Jimble jellyfish, sea anemones and tropical marine stings of unknown origin||1. Follow DRSABCD.
2. Calm patient.
3. Flood stung area with vinegar for at least 30 seconds.
4. If vinegar is not available, flick tentacles off using a stick or gloved fingers.
5. Ensure 000 has been called or emergency beacon activated.
After the incident, ensure that the patient has a current tetanus vaccination. In some cases, pain relief is appropriate g. paracetamol or an antihistamine (to reduce swelling, redness and itch), but consult with a medical professional first.
If you are unsure what animal bit or stung you, apply a precautionary approach, and manage it as though it is a venomous bite, and seek medical help immediately.
The four procedures we’ll cover here are:
- Pressure immobilisation, to reduce the movement of venom in the lymphatic system.
- Ice pack for pain management by reducing the flow of blood to the affected area and reducing inflammation and swelling that causes pain.
- Hot water & vinegar to denature the protein in the stinger.
Pressure Immobilisation Applying a pressure immobilisation bandage
The pressure immobilisation technique was developed in the 1970s as a technique to slow the movement of venom throughout the body. Research has shown that when pressure is applied to the bite area, less venom reaches the bloodstream.
Pressure immobilisation is appropriate for bites from Funnel-web and Mouse spiders, snakes, Blue-ringed octopus, cone shells and sea snakes. Do not use pressure-immobilisation for spider bites other than from a funnel web spider, jellyfish stings, stonefish and other fish stings, bites by scorpions, centipedes, beetles.
This video from the Australian venom research unit shows how to pressure immobilise a lower limb.
For bites to the lower limb, the Australian venom research unit suggests the following steps:
- DRSABCD, send for help by calling 000 if in reception, or triggering an emergency beacon.
- Apply a broad pressure bandage over the bite site as soon as possible. Crepe bandages are ideal, but any flexible material may be used. Clothing, towels etc may be torn into strips. Panty hose have been successfully used. Do not take off clothing, as the movement of doing so will promote the movement of venom into the bloodstream. Keep the bitten limb, and the patient, still. Bandage upwards from the lower portion of the bitten limb. Even though a little venom may be squeezed upwards, the bandage will be more comfortable, and therefore can be left in place for longer if required.
- The bandage should be as tight as you would apply to a sprained ankle.
- Extend the bandage as high as possible up the limb.
- Apply a splint to the leg. Any padded rigid object may be used as a splint. E.g. spade, piece of wood or tree branch, rolled up newspapers etc – with towel or clothing as padding.
- Bind it firmly to as much of the leg as possible. Keep the patient still and relaxed. Lie the patient down to prevent walking or moving around. Monitor patient and wait for rescue services to arrive.
For bites to other parts of the body, the Australian venom research unit suggests the following.
Bites to the hand or forearm
Bandage as much of the arm as possible, starting at the fingers. Use a splint to the elbow.
Use a sling to immobilise the arm. Keep the patient still. Lie the patient down to prevent movement walking or moving around.
Bites to trunk
If possible apply firm pressure over the bitten or stung area. Do not restrict chest movement. Keep the patient still.
Bites to head or neck
No first aid for bitten or stung area. Keep the patient still.
DOs and DON’Ts
The Australian venom research unit also makes the following points:
- DO keep the patient still and limit patient transportation as much as possible.
- DO apply pressure-immobilisation first aid even if the venom appears to have already got into the bloodstream: the application of pressure-immobilisation first aid may prevent further absorption of venom from the bite or sting site during transport to hospital.
- DO keep bandages and splints on until the patient reaches medical care.
- DO NOT cut or incise the bitten area.
- DO NOT apply an arterial tourniquet. (Arterial tourniquets, which cut off the circulation to the limb, are potentially dangerous, and are no longer recommended for any type of bite or sting in Australia.)
- DO NOT wash the bitten area or suck the bite. The type of snake involved may be identified by the detection of venom on the skin. If the snake can be safely killed, bring it to the hospital with the victim.
Ice Pack Applying an Ice Pack
Cold therapy is used for pain management. The idea is to use ice to reduce the flow of blood to the affected area and reducing inflammation and swelling that causes pain.
An ice pack is a plastic sack filled with liquid or gel that can be used to treat injuries including bites and stings, swelling and sprains. Ice packs are generally kept in refrigerators and are often seen in an urban context at sporting competitions.
For remote areas, people can carry instant ice packs instead. These ice packs consist of two separate bags containing ammonium nitrate, calcium ammonium nitrate or urea. When the user breaks the seal between the two bags, the contents mix and cause an endothermic reaction to occur which sucks all the warmth from the surroundings and lowers the ice pack temperature.
Ice packs should be used for red-back spiders (and other spiders excluding Funnel-web and Mouse spiders), bees, European wasps, ants, ticks, scorpions, centipedes. In general, these species cause painful bites, but generally do not lead to medical complications.
For ice pack treatment, St John’s ambulance suggests:
- Follow DRSABCD (in most cases, SABCD parts are not required).
- Apply a cold compress or ice pack directly over the bite site to relieve the pain.
- Seek medical aid if necessary.
Hot Water Applying Hot Water
Hot water helps to relieve some types of stings by denaturing and inactivating the venom.
For some marine species, immersing the sting area in hot water provides relief, and is the recommended first aid for the following species by St John’s Ambulance: Blue-bottle (Pacific Man-O-War) jellyfish, Bullrout fish, Catfish, Crown-of-Thorns starfish, Stingray, Stonefish and nontropical minor jellyfish. These species can cause fatalities and an emergency 000 call or activation of an emergency beacon must be made.
St John’s Ambulance suggests the following steps:
- Follow DRSABCD action plan.
- Calm patient.
- Place patient’s stung limb in hot water (around 40 ℃). Beware the injured person will have an a distorted sense of pain, so the temperature must be as much as the first-aider can tolerate without causing burns.
- Ensure call for ambulance has been made – triple zero (000) – or emergency beacon activated.
Vinegar Applying Vinegar
Likewise, vinegar helps to relieve other types of stings by denaturing and inactivating the venom.
The species that vinegar is the recommended treatment for include:
Box, Irukandji and Jimble jellyfish, sea anemones and tropical marine stings of unknown origin.
St John’s Ambulance suggests the following steps: