Pedestrian safety from snakes and snake bites
South Africa has several endemic snake species. Just mentioning the word snake is enough to send cold chills down most people’s backs. Despite, most people having a phobia for snakes. Snakes are relatively common and people, coming in contact with snakes is occurring more and more often. Traditionally snakes were mostly seen on the rural areas and farms, or at the least were properties were very bushy or if there were bushy surroundings.
However encounters in urban areas are becoming common, especially along the coastal belt and areas with high humidity.
We have just come out of winter and with spring already here, temperatures have started to rise. This is normally when snakes start becoming more active, as most species hibernate or at least become less active due to the decreased temperatures slowing down their metabolism in winter.
As a result this is the time of year that as EMS we start receiving more calls for patients, who have been bitten by snakes, while over a time frame of a year we will respond to several hundred suspected snake bite cases, in KZN alone.
WHY DO SNAKES HAVE VENOM
Snakes mainly use their venom to kill or cause a disability to their pray. It is also less commonly used to defend themselves from a perceived threat. This is the most plausible reason as to why a snake would bite a human. Different species of snakes have different kinds of venom, which is modified saliva, with different chemical make ups and as a result, have different effects on humans. The majority of venoms are not harmful least fatal to humans in the doses that are injected into the body during a bite. However there are several species of snakes that have very toxic venom, which propagates our fear of snakes.
VENOM PRODUCTION AND DELIVERY TO VICTIM
The venom a snake produces is stored in venom glands located in the snakes head. When the snake wishes to deliver the venom the snake bites the victim, sinking their fangs onto the victims flesh. The fangs, which are hollow (or in some cases grooved), are connected to the venom glands and the venom is injected through the hollow fangs into the victim.
TYPES OF VENOM
There is continued research being carried out on snake venom, which is expanding our understanding of venom and how it works and snake venom and its chemical properties have been used to help develop certain medications. The venoms that are dangerous to humans can be divided into several main types of venoms, with certain snake species producing these venoms which a have specific effect on humans.
This type of venom affects the clotting factors in blood, resulting in haemorrhaging due to the blood not being able to form blood clots. The obvious effect of this venom is normally delayed, while a complex chemical process affects the blood, which then results in defuse bleeding. With intensive treatment most cases are not fatal.
Examples of snakes, what produce this type of venom, are the Boom Slang and Vine snake. Fortunately these snakes are sly and have smaller fangs, which limit penetration in to flesh, especially through clothing.
This is arguably the most dangerous type of venom. The venom affects the ability of the bodies’ nerves, to transmit nerve impulses, which ultimately results in paralysis. This results in respiratory failure due to the lungs not being able to receive the nerve impulses from the brains respiratory center.
The snakes in the Mamba and some in the Cobra family produce neurotoxic venom. Examples of these snakes that we see are the black and green mamba as well as the several types of cobra, including the Cape cobra and Ringhals or ring-necked spitting cobra .
The Black Mamba
The Green Mamba
This venom destroys the cells mostly near the area of the bite and also results in massive swelling, which can result on associated medical emergencies, such as crush syndrome and occlude blood flow past the affected area, which is of particular concern if the bite is on a limb. While these bites are not always fatal if appropriate intensive medical care is provided, the bites are also said to be very painful and morbidity is worsened by the associated medical problems and infection that can develop from these bites.
The species of snake that produce cytotoxins are the Adder species, examples of which are the Puff Adder, Night Adder and Berg Adder.
The Gaboon Adder
The Night Adder
The Puff Adder
The potency of the venom of wild snakes varies considerably, even within any single species. This is because of assorted influences such as biophysical environment, physiological status, ecological variables and genetic variation.
Irrespective of the species or family of the snake the following factors also affect the effect of the venom on the victim:
- The amount of venom injected during the bite. Most snakes’ venom is as effective when they are still juveniles, however the quantity of venom available to inject will be less, the depth the smaller fangs will be able to penetrate will also be shallower.
- Some snakes are rumored to give what is called a “Dry bite” there the victim is bitten but there is no venom released during the bite. This could be due to the venom being finished or could possibly be due to the snake deciding not to release the venom.
- The area on the body where the snake strikes.
- The smaller the victim, i.e. a child or baby, the greater the effect of the venom will be. The amount of venom injected will be the same as if it was an adult bitten but the dose will be effectively higher due to the deceased body size of the child.
TREATMENT OF A SNAKE BITE
Precise treatment of the various kinds of snake venoms is considerably different and is best left to medical professionals.
However there are some general principles that can be followed while accessing medical help:
- Although it sounds strange, STAY CALM! Any activity including panicking will increase the victim’s heart rate which will circulate the venom in the body faster. This includes by standers or people trying to help the victim as they may inadvertently be causing the patient to stress.
- Limit activity. After moving away from the danger area, any form of activity, be it running, walking, pacing up and down, needs to be limited as combined with the stress of already have been bitten by a snake this will defiantly increase the victims heart rate.
- If driving to a medical facility preferably have someone else drive.
There are many myths regarding snake bite treatment, many of which simply worsen the situation.
- Do not wait for symptoms to develop before seeking medical attention.
- Do not use a tourniquet (a tourniquet is a tight encircling band or belt applied around an arm or leg) as a tourniquet, in the long run, can cause complications.
- Do not cut the bite area in an attempt to make it bleed
- Do not try suck the venom out the wound
- Do not apply heat or cold packs to the bite area
The snake does not have to be killed and brought with when seeking medical attention. This wastes time in seeking help and increases the risk of being bitten again. Medical professionals will treat you according to the symptoms you present with, which will also identify which family of snake was involved.
Anti-venom has been developed to combat the effects of certain snakes venom. It is not effective against all snake venoms and there for cannot just be administered as it may cause a life threatening anaphylactic reaction.
Anti-venom which is also very expensive has a short shelf life and needs to be kept refrigerated, needs to be administered by trained medical professionals in a controlled manner, as several medications need to be given in conjunction with the anti-venom, mainly to try prevent an anaphylactic reaction to the anti-venom.
AVOIDING BEING BITTEN BY A SNAKE
The age of saying of prevention is better than cure is pertinent when it comes to snake bites.
The following can be done to avoid been bitten:
- When hiking or walking in a wilderness area, stick to the path and avoid grassy, bushy areas, where snakes may be hiding. Also wear boots, long pants and a long sleeved shirt
- Be careful when picking up objects, where snakes may be hiding under. The classic example is logs, which are being sought as fire wood.
- Don’t try catch or prod snakes with a stick, most snakes can strike two thirds of their length, when resting.
While most people avoid contact with snakes at all costs, encounters with snakes are inevitable. Snakes will also most often try and avoid a confrontation with a human. Most snake venom does not have serious effects on humans, however after being bitten by a snake medical advice must be sought, don’t wait for symptom to develop before seeking help.