Snake bite

list of contents

• Introduction
• What is the nature of snakes?
• Is a snake bite dangerous?
• What are the side effects of a snake bite?
• Types of venomous snakes and areas where they are found.
  • Neurotoxins: Thai cobra, spitting cobra, king cobra, krait, banded krait, and Malayan pit viper.
  • Hemotoxic venom: Malayan pit viper, banded krait, green pit viper.
  • Kidney-damaging: Rufous snake bites.
  • Green mamba snake (Dendroaspis angusticeps)
• What are the symptoms of a venomous snake bite?
• What should you do as first aid if bitten by a snake? When should you see a doctor?
• Things you shouldn’t do when bitten by a snake.
• How do doctors treat patients bitten by venomous snakes?
• How to prevent snake bites?
• bibliography

Snake bites are a significant public health problem in Thailand. They are common, especially during floods, as Thailand’s tropical climate and topography are conducive to snake habitation. There are approximately 163 species of snakes in Thailand. The most important and urgent problem is venomous snake bites. Identifying the type of venomous snake and providing timely and appropriate treatment can significantly reduce the risk of serious injury, which in some cases can be fatal.

What is the nature of snakes?

Most snakes bite when startled or threatened. If possible, they will usually flee from people. Snakes are often found near or in water, and most are non-venomous. However, if bitten by a snake and the type is unknown, it’s a serious problem, and you should consider the possibility of a venomous snake for safety reasons. This is especially true for children, who are smaller and lighter. A venomous snake bite in children can cause more severe symptoms than in adults because the amount of venom is greater relative to their body weight.

Is a snake bite dangerous?

Since most snakes are non-venomous, a bite may cause a painful wound or lead to infection if the wound is dirty. However, most people don’t know much about snakes or whether one is venomous or not. Therefore, it’s crucial to assume that a snake bite could be venomous. Follow the recommendations below and seek medical attention immediately; going to a hospital is preferable if possible. Nevertheless, prevention is the best approach.

What are the side effects of a snake bite?

Possible side effects from a snake bite include:

1. Local effects from snake venom or certain enzymes/substances in snake saliva can cause extensive tissue necrosis at the bite site, resulting in loss of muscle, tissue, and surrounding skin. The snake bite may also become bacterially infected. In some cases, skin grafting is necessary, where healthy skin is transplanted to replace the damaged skin.
2. Snake venom poisoning can affect the nervous system, blood system, and cause kidney failure. However, with proper treatment, including antivenom serum appropriate to the type of snake and indications, along with supportive care, most patients recover. But if treatment is not received correctly and promptly, patients may die from respiratory failure or heart failure. This is because snake venom affects the heart, causing arrhythmias, or from high potassium levels caused by the venom disrupting red blood cells and muscle tissue, or affecting blood clotting, leading to excessive bleeding from the wound or other tissues/organs and ultimately death.

Types of venomous snakes and areas where they are found.

Venomous snakes in Thailand are divided into three main groups:

1. Neurotoxic venom: Thai cobra, spitting cobra, king cobra, krait, banded krait.

Neurovenomous snakes include:

• The Thai cobra (Naja kaouthia) is found throughout the country, with a high concentration in the central and lower northern regions.
• The spitting cobra (Naja siamensis) is commonly found in the northeastern, central, northern, and western regions of Thailand.
• The king cobra (Ophiophagus hannah) is commonly found in southern Thailand and some provinces in central Thailand.
• The banded krait (Bungarus fasciatus) can be found in all regions of the country.
• The Malayan krait (Bungarus candidus) is commonly found in the northeastern, southern, and eastern regions of Thailand.

2. Hemotoxic venom: Malayan pit viper, banded krait, green pit viper.

Venomous snakes that affect the blood system: Divided into 2 subgroups.

• The first group includes the typical viper, commonly found in the eastern and central regions of Thailand.
• The second group consists of Pit vipers, including:
  • The Malayan pit viper is commonly found in the southern coastal regions, the eastern coast, and the northern part of Thailand.
  • Another species is the green pit viper, commonly found in Bangkok, central Thailand, and northeastern Thailand.

3. Kidney-toxic: Malayan pit viper.

Kidney-damaging venom: This is found in the Malayan pit viper. The venom effect may be direct, or indirect, due to other causes such as shock or the excretion of hemoglobin (the pigment that gives red blood cells their color) through the kidneys.

The most common venomous snake that bites Thai people is…

• The Malayan pit viper (40%) was the second most common snake.
• Green pit viper (34%)
• Cobra (12%)
• The Malayan pit viper (10%) and
• Other snake species (4%)

Furthermore: Regarding the Green mamba (Dendroaspis angusticeps): During the great flood of 2011, while people in Bangkok were suffering from the massive inundation, news emerged that added to the anxiety: someone was secretly keeping a Green mamba, a snake native to Africa, which had escaped.

4. Green mamba snake (Dendroaspis angusticeps)

The green mamba is a snake with neurotoxic venom that causes muscle paralysis due to a toxin called muscarinic toxin. Detailed studies of the green mamba’s venom composition have found that it is more than 50% similar to the venom of the common Thai cobra (Naja kaouthia), as mentioned earlier. In Zimbabwe, a study of numerous snake bites found that 18% of patients were bitten by black and green mambas, compared to 37% by cobras.

However, the overall mortality rate from venomous snake bites is relatively low, at only 1.8%. Treatment is effective with antivenom serum, antibiotics, painkillers, tetanus vaccine, and supportive care to address the symptoms of the snake bite. This is a generally similar treatment approach for all types of venomous snake bites, as will be discussed further in the section on snake bite treatment, including those from the Green mamba. The difference lies in the type of antivenom used, which must be specific to the type of venomous snake; for example, Green mamba antivenom is used for bites from that species.

What are the symptoms of a venomous snake bite?

Because snake venom contains many types of proteins and enzymes, it affects the bite site and can cause a variety of symptoms throughout the body.

• Effects on the bite site: There will be two fang marks, pain, swelling, a burning sensation, bleeding at the bite site, or widespread inflammation (swelling, redness, heat). There may also be swelling and tissue necrosis in the area. Skin color may change from its normal shade, such as darkening or blistering.
• Systemic effects: These depend on the type of snake venom.
  • Neurotoxin poisoning in snakes causes symptoms such as double vision, blurred vision, and drooping eyelids, which usually occur within 1 to 10 hours after snake venom exposure. This is followed by muscle weakness, muscle incoordination, slurred speech, difficulty swallowing, and difficulty breathing.
  • Venomous snakes that affect the blood system: Symptoms include abnormal bleeding from various wounds, including snake bites, gums, skin, under the skin, in muscles, in the digestive tract, in the urinary tract, and from needle punctures.
  • Venomous snake bites that can cause kidney failure may result in: inability to urinate, high blood pressure, swelling, electrolyte imbalance, and possibly shortness of breath.
• Other systemic effects: In addition to those mentioned, there may be other common symptoms such as:
  • I have a fever.
  • Unconscious
  • low blood pressure
  • Nausea and vomiting
  • Diarrhea or
  • Allergic reaction to snake venom (swelling, redness, itchy rash; may occur all over the body or only in specific tissues/organs).

What should you do as first aid if bitten by a snake? When should you see a doctor?

Since we often don’t know the type of snake, when bitten, assume it’s venomous. First aid and medical attention after a snake bite include:

1. Keep the patient still and relaxed, and position the snakebite site below the heart to slow the spread of the venom into the body/bloodstream.
2. Remove any rings or constrictors from the snakebite area, as they may become impossible to remove if swelling occurs. Use a splint or loose brace to immobilize the bite area to reduce movement, as movement accelerates the spread of venom into the body.
3. Observe the bite site. If there is swelling or a change in color, suspect a venomous snake bite.
4. If possible, check vital signs: is the pulse weak and rapid? Are respiration and blood pressure normal? Is there a fever? If there are signs of shock, such as pale face, dizziness, or fainting, have the patient lie flat with their feet elevated about 1 foot and cover them with a blanket.
5. Rush the victim to a hospital as soon as possible (emergency). Do not assume that mild pain is harmless, as some people experience no pain the first time they are bitten, but later develop other severe symptoms that can be fatal. Call the hospital en route to arrange for immediate medical attention and serum preparation.
6. If possible and safe for the caregiver, bring the dead snake to the doctor for identification or take a picture of it. However, do not waste time chasing the snake, as it may bite again. Also, be aware that a dead snake may be able to bite again while being brought to the doctor (due to a reflex), which can occur within an hour of death, so be especially careful around the snake’s head.
7. After seeing the doctor and being given permission to return home, follow the doctor’s and nurse’s instructions, including those for caring for the snake bite wound.
8. When your doctor schedules an appointment, if you become concerned about your symptoms or if they worsen, such as a worsening wound, increased pain or swelling, or fever, see your doctor before your scheduled appointment. You should see a doctor within 1-2 days of experiencing any unusual symptoms. Seek emergency medical attention immediately if you experience any severe or recurring symptoms, such as uncontrollable bleeding from any area, high fever, weakness in the arms or legs, or nausea and vomiting.

Things you shouldn’t do when bitten by a snake.

When bitten by a snake, you must ‘not’:

1. Avoid allowing the patient to exercise or move excessively, as this can cause snake venom to enter the bloodstream more quickly. If necessary, the patient may need to sit or lie down in a wheelchair or in a reclined position.
2. Do not tie a tight tourniquet to the snakebite site. Tightening the tourniquet can cause tissue necrosis or swelling due to reduced blood supply. Instead, wrap a cloth or rope above the bite area to a small piece of wood, allowing your fingers to pass underneath. This method can keep the patient comfortable for several hours. Do not remove the tourniquet or rope until you reach the hospital, as the venom will enter the bloodstream more rapidly once removed. However, this method may not be effective against snakes that cause localized venom, such as cobras and green pit vipers.
3. Do not apply a cold compress to the snakebite area because the venom may enter the bloodstream more quickly, and a cold compress may cause further tissue death.
4. Do not use sharp objects to cut or cauterize the snakebite area, or apply medication to the wound, as this may lead to severe infection.
5. Do not suck out snake venom with your mouth because the venom can harm the person sucking it out or cause infection at the snake bite site.
6. Do not give the patient any stimulants, painkillers, or medications unless advised by a doctor. If the pain is severe, give paracetamol. Do not allow the patient to drink alcohol, as this may lead to a misjudgment of the patient’s consciousness.
7. Do not give the patient food or water because it may cause aspiration, airway obstruction, and death, or lead to severe pneumonia, especially in those who have been poisoned by a snake venom that affects the nervous system.
8. Do not place the bitten limb above the heart, as this will allow the venom to enter the bloodstream more quickly.

How do doctors treat patients bitten by venomous snakes?

The doctor treated a patient bitten by a poisonous snake by…

1. The doctor will assess the patient’s breathing and cardiovascular system to determine if they are functioning normally or if any initial treatment is required. If the patient has applied a tourniquet above the wound, the tourniquet will be loosened (after the patient’s assessment). The wound will then be cleaned.
2. The doctor will ask about the snake bite, including the time of the bite before arriving at the hospital and the type of snake. If unsure, the doctor will compare the snake’s image to pictures in books or online. The doctor will then examine the bite marks to verify if it was a snake bite.
3. The doctor will assess whether the snake bite was venomous or not, and if so, what type of venom it was—neurotoxic, hemotoxic, or nephrotoxic. The doctor will then take blood samples to check for abnormalities as needed and based on the evidence.
4. The doctor will assess whether the symptoms are localized to the bite site or generalized, and the severity of the symptoms (mild, moderate, or severe) (the doctor will have a guideline for evaluation). The first symptoms indicating snake venom entry are often nonspecific, including nausea, vomiting, and abdominal pain. Therefore, if these symptoms are present, additional tests may be conducted to immediately detect various snake venom symptoms, such as a complete blood count (CBC) or kidney function tests.
5. The physician will consider administering antivenom based on the indications and the type of snake.
6. The physician will provide other supportive care as indicated, and when necessary, such as blood and blood component transfusions if the poison affects the blood system, mechanical ventilation if breathing is impossible due to neurotoxicity, dialysis in case of renal failure, treatment of shock if present, treatment of infection if indicated, tetanus vaccination, pain medication, and wound treatment.
7. In cases where a patient is bitten by a venomous snake but is asymptomatic, doctors usually admit the patient to the hospital for at least 24 hours to monitor their condition and closely watch for any potential subsequent symptoms.

How to prevent snake bites?

Preventing snake bites is the best way to treat snake bites and prevent side effects, which include:

1. Avoid entering areas where snakes like to hide, such as under rocks, logs, overgrown areas, or piles of clothes and objects in dark places, especially during floods when snakes are fleeing the water. When entering a bathroom located in a low area where snakes can hide, ensure there is sufficient lighting.
2. Never play with snakes unless you are well-trained.
3. When walking in overgrown or dark areas, use a stick to clear a path to scare snakes away, ensuring there are no snakes present.
4. If you must walk in an area with a high concentration of snakes, wear long pants and boots.

bibliography

1. Paiboon Chintakul, Lawan Chanhom. Venomous Snakes in Thailand. Bangkok: Prachachon Company Limited. 1996.
2. Anupap Lekhakul. Patients bitten by venomous snakes. In: Thanin Intrakamthornchai, editor. Guidelines for the treatment of hematological diseases in Thailand. Bangkok. Beyond Publishing, 2000, pp. 273-80.
3. Kasilo OM, Nhachi CF. A retrospective study of poisoning due to snake venom Zimbabwe. Hum Exp toxicol1993;12:15-8.
4. Kukhtina W, Weise C, Muranova TA, et al. Muscarinic toxin-like proteins from cobra venom. Eur J Biochem2000;267:6784-9.
5. Nhachi CF, Kasilo OM. Snake poisoning in rural Zimbabwe-a prospective study. J Appl Toxicol1994;14:191-3.
6. https://medlineplus.gov/ency/article/000031.htm [2020,Oct3]
7. https://www.uptodate.com/contents/search?search=principles-of-snake-bite-managementworldview&sp=0&searchType=PLAIN_TEXT&source=USER_INPUT&searchControl=TOP_PULLDOWN&searchOffset=1&autoComplete=false&language=&max=0&index=&autoCompleteTerm= [2020,Oct3]