What is the Difference Between Neurotoxic and Hemotoxic Venom

The main difference between neurotoxic and hemotoxic venom is that the snakes in the Elapidae family produce neurotoxic venoms, whereas the snakes in the Viperidae family produce hemotoxic venoms. 

Neurotoxic and hemotoxic venom are two snake venom types. They occur in the saliva of snakes and are highly toxic. They facilitate the immobilization and the digestion of the prey.

Key Areas Covered

1. What is Neurotoxic Venom
– Definition, Facts, Importance
2. What is Hemotoxic Venom
– Definition, Facts, Importance
3. Similarities Between Neurotoxic and Hemotoxic Venom
– Outline of Common Features
4. Difference Between Neurotoxic and Hemotoxic Venom
– Comparison of Key Differences

Key Terms 

Hemotoxic Venom, Neurotoxic Venom

What is Neurotoxic Venom

Neurotoxic venom is a type of snake venom that target the nervous system. There are three types of neurotoxic venom: fasciculins, dendrotoxins, and alpha-neurotoxins.

Fasciculins

Fasciculins attack cholinergic neurons that use acetylcholine as the transmitter. It destroys the acetylcholinesterase enzyme that breakdown acetylcholine. Therefore, acetylcholine stays in the receptor and cannot break down it. It causes involuntary muscular contractions (tetany) and leads to death. Therefore, fasciculins cause rapid muscle contractions. It occurs in snakes like mambas and rattlesnakes.

Figure 1: Alpha-Bungarotoxin

Dendrotoxins 

Dendrotoxins inhibit neurotransmission. They block the exchange of positive and negative ions across the membrane of neurons. It causes no nerve impulses through the nerve cells. Thereby, it paralyzes the nerves. Snakes like mambas contain those venoms.

Alpha-Neurotoxins 

Alpha-neurotoxins are a large group of neurotoxins that attack nicotinic acetylcholine receptors. In the cholinergic neurons, alpha-neurotoxins mimic the shape of the acetylcholine molecule. It fits into the acetylcholine receptors causing numbness and paralysis. Snakes such as king cobras, sea snakes, many-banded kraits, and cobras contain this venom. 

What is Hemotoxic Venom 

Hemotoxic venom is another type of venom in snakes and destroys red blood cells, inducing blood coagulation. These venoms contain enzymes and proteins that are hemotoxic. Hemotoxic venom also causes generalized tissue damage and organ degeneration. Usually, the toxins damage blood and damage other tissues as well. Injury from hemotoxic agents is painful and causes severe death and permanent damage. Snakes such as cobras, many vipers, and the tropical rattlesnake have hemotoxic venom.

Figure 2: Rattlesnake

Similarities Between Neurotoxic and Hemotoxic Venom

• Neurotoxic and hemotoxic venom are two types of snake venom.
• They help in the immobilization and digestion of the prey.
• They are highly toxic and occur in the snake’s saliva.

Difference Between Neurotoxic and Hemotoxic Venom

Definition

Neurotoxic venom refers to the toxins that are destructive to nerve tissue. In contrast, hemotoxic venom is snake venom that destroys explicitly red blood cells, affecting tissues and internal organs.

Occurrence

The snakes in the Elapidae family produce neurotoxic venoms, while snakes in the Viperidae family produce hemotoxic venom. 

Function

Neurotoxic venom attacks the nerve cells, while hemotoxic venom destroys red blood cells, inducing blood coagulation.  

Activity

Neurotoxic venom envenomation occurs during sleep, while hemotoxic venom envenomation occurs while awake.

Snake Involved 

Neurotoxic venom occurs in krait and cobras, while hemotoxic venom occurs in vipers and rattlesnakes. 

Seasonal Distribution

Snakes use neurotoxic venom from June to August, while snakes use hemotoxic venom all year around. 

Strength of the Venom

Neurotoxic venoms are strong, while hemotoxic venoms are weak.

Immediate Pain and Swelling

No local pain in neurotoxic venoms, while several local pain and swelling occur in hemotoxic venom.

Onset Systemic Envenomation

Onset systemic envenomation occurs within 1-2 days, while onset systemic envenomation occurs within 12-48 days.

Clinical Features

Clinical features of neurotoxic venom include ptosis, dysphagia, respiratory distress, quadriparesis, and early morning neuroparalysis, while clinical features of hemotoxic venom include gum bleed, renal failure, hematuria, and bleeding manifestation. 

Outcome

Neurotoxic venoms cause death if treatments are delayed, while hemotoxic venoms have a high survival rate even with delayed treatments. 

Conclusion

In brief, neurotoxic and hemotoxic venom are two types of snake venom highly toxic to humans. Neurotoxic venom occurs in the snakes of the family Elapidae that attack the body’s nerve cells. Envenomation of neurotoxic venoms occurs during sleep. Krait and cobras are responsible for neurotoxic venoms that bite from June to August. However, neurotoxic venoms are strong and do not produce local pain. Onset systemic envenomation occurs in 1-2 days and can cause death if treatments are late. In comparison, hemotoxic venom is produced by the snakes in the family Viperidae. Also, it destroys red blood cells causing blood coagulation. Envenomation occurs while awake, and snakes such as vipers use hemotoxic venoms all year around. They are weak venoms that produce local pain and swelling. Onset systemic envenomation occurs within 12-48 days. However, survival is possible even if the treatments are late. Therefore, the main difference between neurotoxic and hemotoxic venom is the type of snakes they are produced.  

References:

1. Osipov A, Utkin Y. What Are the Neurotoxins in Hemotoxic Snake Venoms? Int J Mol Sci. 2023 Feb 2;24(3):2919. doi: 10.3390/ijms24032919. PMID: 36769242; PMCID: PMC9917609.

Image Courtesy:

1. “Alpha-Bungarotoxin 1IDI” By Fvasconcellos – Own work (Public Domain) via Commons Wikimedia
2. “Crotalus cerastes mesquite springs CA-2” By Victorrocha – Own Work (CC-BY SA 3.0) via Commons Wikimedia