SNAKES AND VENOM THINGS YOU NEED TO KNOW

The global threats of snakebites and the clinical features of Envenomation by Australian Elapids 25th May Sadequa RAHMAN

When we talk about snakes we draw a scary picture of them in our mind. Most of us are scared of snakes but are all of them poisonous? How can we classify them? How many species are there? What is the current risk of death percentage from snake bites? Questions like these arise in our mind when we think about this scary reptile. Let’s talk about this slimy creature in brief and explore some important facts to analyse in this article. The classification System for snakes There are approximately 3400 species of snakes and about 300 species are venomous. All of them have some common features like scales and no eyelids, no ear opening and also have the same suborder.[1] According to the scientific classification snakes belong to the class- reptilia, order- squamata same order where Lizards belong to sub-order– serpents.[1][2] There are about 20 prominent families but most of the species belong to 5 major families -

1. Colubridae -The largest snake family but very few in Australia - Browntree snake. Most of these species are non-venomous.

2. Viperidae - Most common family in united snakes but not found inAustralia. All of these species are venomous and most of them secretshaemotoxic venom that leads to bleeding of the victim i.e. rattle snake,water moccasins, viper, saw-scaled viper

3. Elapidae Main species found in Australia. Small headed and short fixedfang to inject the neurotoxin venom to the prey and our central nervoussystem is affected. i.e. King Cobra,Black,Mamba, Coral snake, kraitsare the main members of this family

4. Pythonidae- This family has the longest snakes in the world and areKnown as ‘python’

5. Boidae- All the members of this family are non venomous but they are heavy, large and very strong. They kill their prey by hard constriction i.e Green Anaconda is a member of this family

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Classification system

Of snakes -

KINGDOM: Anamalia PHYLUM: Chordata CLASS: Reptilia ORDER: Squamata

SUB-ORDER: Serpentes

FAMILY: Over 20

GENUS : Over 3400 SPECIES : Species

Global snakebites problem – how big is it? Approximately 5.5 million people are being the victim of envenomation per year causing about 400,000 amputations with 20-125, 00 people to loss their lives.[9] Snakebite is now listed into the top twenty neglected tropical disease according to the WHO and considered as an extreme global threat. Sometimes it gets harder to distinguish the venomous and non venomous species and the types of A short film

snake bites specially in rural areas as there are lack on snake bite

of proper knowledge in the community. As a result it has become a severe community threat for some underdeveloped and developing countries. Not only the human but the pets are also being the victims of envenomation.We are so lucky that in Australia the death toll is not too high comparing to other countries. Unfortunately, The highest number of death is reported in South Asian contries and India has got the highest death toll per year among them as it is the great home for the world’s most venomous snakes.[11] Most people there do not have the proper knowledge and are not aware of emergency procedures and first aids for the snakebites and also some superstitions are major issues behind this. Also some african countries are on high risk catagory because they do not have the antivenom therapy available for all to treat because the antivenom therapy is quite expensive and not in reach for the poor people who need it more. So the death toll is rising up in the sub-saharan Africa.[11] A new study has found that venomous snakes are getting more and more venomous by acquiring new genetic codes and that will be frightening as the new genetic development in the snake venom can make it resistant to and will make it harder for us to fight against it.

Clinical features following envenomation by Australian elapids Australian snake envenomation is rarely life threatening though sometimes it can become a challenge to manage the clinical conditions. Not all snakebites will present clinical features because the amount of venom injected by the snake is not enough or not bitten by the venomous snake. But snakebites are always given the topmost priority[4]. Most common and major clinical features includes-

Sudden collapse- often occurs after the bite within an hour with low blood pressure and the victim loss consciousness but recover within several minutes. There are very few risks to have a cardiac arrest from this. It isvery common when bitten by brown snakes.

VICC (Venom induced consumptive coagulopatghy)-Coagulopathy happens with the consumption of clotting factors in our blood by the release of prothrombin activator toxin and cause high INR (International normalised ratio) and aPTT (activated partial thromboplastin time) results with high d-dimer level. Most of cases the victimm needs antivenom therapy to improve the condition. Microangiopahy is considered as the first step to identify the VICC condition. Mulga and red bellied snake bites are mostly considered to be responsible for this condition.

Neurotoxicity- It is a descending process of paralysing that starts with the eye muscle and continues to paralyse

the respiratory muscle following the lower limbs of the body

Myotoxicity- Muscle aches and get weaker with dark urine

Potassium level in the blood rises up and cause renal impairment with muscle tenderness.

Thrombic microangiopathy cause fragmented red cell and thrombocytopenia with high creatinine level and renal failure can be the possible effect

Systemic symptoms

Nausea, vomiting, headache, diarrhoea, abdominal

pain

So, it is vital that we need to be cautious and have some basic knowledge about the snakes. Also we need to learn the first aid and emergency procedures for snakebites so that we can at least minimise some fatal consequences.

REFERENCES

1. Peters, J., Wallach, V., 2018, ‘Snake’, Encyclopædia Britannica, Viewed 18th May 2018,< https://www.britannica.com/animal/snake>

2. Reptile Knowledge Reptile Conservation and Care Information 2015 The ColubridaeFamily of Snake - Colubrids, Viewed 18 May 2018,

< http://www.reptileknowledge.com/squamata/colubridae.php>

3. Mehrtens, John M. Living Snakes of the World. New York. Sterling Publishing Co., Inc.1987.

https://seaworld.org/en/animal-info/animal-bytes/reptiles/snakes

4. Geoffrey K Isbister, Simon G A Brown, Colin B Page, David L McCoubrie, Shaun LGreene and Nicholas A Buckley

Med J Aust 2013; 199 (11): 763-768. || doi: 10.5694/mja12.11172 https://www.mja.com.au/journal/2013/199/11/snakebite-australia-practical-approach-diagnosis-and-treatment#8

5. Published online 2008 Nov 4. doi: 10.1371/journal.pmed.0050218

6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577696/

7. http://www.who.int/snakebites/en/

8. Hoang X. Pham & Michael E. Mullins (2018) Safety of nonsteroidal anti-inflammatorydrugs in copperhead snakebite patients, Clinical Toxicology, DOI:10.1080/15563650.2018.1468447

9. https://theconversation.com/snakebites-still-exact-a-high-toll-in-africa-a-shortage-of-antivenoms-is-to-blame-80982

10. Médecins Sans Frontières/Doctors Without Borders (MSF)Published on Jun 2, 2016

https://www.youtube.com/channel/UCId9tO5LYlJKgNQKEzgjYOg

11. A Kasturiratne A, Wickremasinghe AR, de Silva N, et al. The Global Burden of Snakebite:A Literature Analysis and Modelling Based on Regional Estimates of Envenoming and Deaths. Winkel K, ed. PLoS Medicine. 2008;5(11):e218. doi:10.1371/journal.pmed.0050218. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577696/

https://www.britannica.com/animal/snakehttp://www.reptileknowledge.com/squamata/colubridae.phphttps://seaworld.org/en/animal-info/animal-bytes/reptiles/snakeshttps://www.mja.com.au/journal/2013/199/11/snakebite-australia-practical-approach-diagnosis-and-treatment#8https://www.mja.com.au/journal/2013/199/11/snakebite-australia-practical-approach-diagnosis-and-treatment#8https://dx.doi.org/10.1371%2Fjournal.pmed.0050218https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577696/http://www.who.int/snakebites/en/https://doi.org/10.1080/15563650.2018.1468447https://theconversation.com/snakebites-still-exact-a-high-toll-in-africa-a-shortage-of-antivenoms-is-to-blame-80982https://theconversation.com/snakebites-still-exact-a-high-toll-in-africa-a-shortage-of-antivenoms-is-to-blame-80982