John F. Taylor
When people talk to me about snakes that are not within the herpetoculture community there are generally two things I can almost guarantee without even knowing the person who I am speaking with.
1) ‘Have ever worked (read into this handled) a ‘poisonous’ snake?’ This of course raises my hackles and I immediately want to generally throttle the media et al for the mass distribution of incorrect information.
2) ‘Have you ever been bitten?’
My answer to both of these is yes. Yes, I have handled venomous animals, and yes I have been bitten. Now this requires some immediate clarification on both points because they are shocked at my reply. I first of all make an attempt to explain that first of all there is a major difference between ‘poison’ and ‘venom’ which I will explain here. The second point is yes I have been technically envenomated once but by a very unlikely source. A small Garter snake Thamnophis sp. but that is for another post.
Poison vs. Venom
By definition a poison is a toxin of some type which may enter the body by ingestion, inhalation, or topical application. The topical portion of this throws some people off, so for that I use the example of poison oak which by the way you can handle its only when its leaves and stems are broken and the sap comes into contact with skin that it has the much renowned results of raising welts and being itchy.
Venom on the other hand is a toxin as well but most of the similarities if not all of them end right there. The toxins in venom are injected by one animal, insect, or arachnid into another animal (such as a human). Snakes (some), bees, wasps, scorpions, spiders, Slow Loris, and even the Platypus (yes they really exist) are all venomous. These venoms have wide array of uses and toxins but for this post we will concentrate on how the are medically relevant. Before going on venom has either one of two of uses according what I have studied. They are either for defense or offense i.e. prey capture.
Hemotoxin & Neurotoxin
For our purposes here we will be discussing venom on a more general level. However, we must understand that there is a lot more going on in venom than just hemotoxin and neurotoxin. Venom is at its base level, a complex cocktail if you will, of varying proteins and peptides which include but are not limited to hemotoxins and neurotoxins. An example of this is myotoxins and cytotoxins which are also found within venomous snakes. As I said above we are covering generalities here so we are going to cover the hemotoxic and neurotoxic properties found within almost all snake venom. For relevance, myotoxins effect muscle tissues directly and cytotoxins effect various cells within organs in the body of mammals.
I am sure we can all understand what a toxin is but just to clarify a toxin is classified as a poison produced by an organism capable of causing disease when introduced to the body. Therefore, a hemotoxin by definition when introduced to the body would attack or cause ‘disease’ via the bloodstream the prefix hemo meaning having to do with blood. While neuro, would have to do with the neurological processes or functions and generally refers to the central nervous system and its components. Now that we have that understanding lets take a look at the actual effects of each on the human body.
So we know that hemotoxin effects the blood so within this realm of venom once a human in envenomated there are some generalities we can expect to see. Hemotoxins when they enter the human body destroy red blood cells which means it disrupts clotting and causes general tissue damage by breaking down the cell walls in the veins and arteries which then allow blood to leak out into the surrounding tissues. This destruction of the veins and arteries then of course leads to the lowering of blood pressure the venom if left untreated may also go to the heart muscle itself. Swelling or edema is the primary reaction to a hemotoxic envenomation as well as intense pain dependent on the amount of venom injected it also may cause bleeding internally as the venom destroys the vein and artery walls.
When it comes to neurotoxins is where for me personally that venom gets really interesting. With a neurotoxic envenomation there may be no local symptoms as would be seen in a hemotoxic venom injection. Neurotoxic venoms enter the blood stream as would any venom injection but the symptoms are not immediately apparent. This is in my opinion due to the fact that the proteins are circulating to the central nervous system where they then react with specific nerves and the electrical impulses that control the aspects of breathing, speech, and so on. Some of the other symptoms of neurotoxic envenomation that have been personally relayed to me are ptosis which is uncontrollable drooping of the eyelids and a metallic taste within the mouth.
Fact vs. Fiction
If you watch any main stream news media feed then you’ll now doubt see the yearly report of when the rattlesnakes are coming out to warm up and tell us we should all be ‘very aware’ because an ‘attack’ can occur at any time. Now then I have read studies which state that there are approximately one rattlesnake per football field. Given that they are trying already to avoid a predator such as a human then it’s in their best interest to stay hidden. They are never out to get humans.
The fact of the matter is you’re more likely to be struck by lightning than you are to be bitten and killed by a rattlesnake[i]. In fact about 25% of all rattlesnake bites are what are known as dry bites which mean that there is no venom injected at the time of the actual bite. This is especially true with defensive bites where the rattlesnake is defending itself against a potential predator. Rattlesnakes make a decision when and where to use venom as this is a resource which they manufacture and one they do not want to waste upon a non prey item such as a human which they know that they cannot eat.
Spending time outside
We’ve all seen the signs at times when entering different hiking trails and or parks “Danger rattlesnakes.” Understand this means that somewhere within the hundreds to thousands of acres that there are or may be rattlesnakes present. The rattlesnakes have not met up the night before and plotted out where they are going to encounter a human in order to bite them. As a matter of fact rattlesnakes use chemical trails left by prey potential prey items to select ambush sites[ii]. So simply being aware of your surrounding areas will keep you safer when out in the ‘wilderness’ when hiking.