Tuesday, June 15, 2010

Snake Bites

source from : http://www.naturemalaysia.com/snake-bites.htm

Poisonous Snakes in Southeast Asia

'Venomous snakes are not poisonous' - The statement above is meant to correct the misnomer of snakes being poisonous, rather than venomous. Poison is something that becomes harmful when ingested or absorbed through the skin while venom is dangerous when injected into the body. Certain frogs, plants and fungi can be poisonous while all snakes that can inject venom are venomous. This is why one can consume snake venom without any ill-effects provided there are no open sores or ulcers in the stomach. So don't be tricked by the wonders of witch doctors or medicine men that perform this act. The venomous snakes of Southeast Asia can be divided into the Elapidae family, which are cobras, kraits, coral snakes and sea snakes; and Crotalidae, belonging to local pit-vipers that are mostly from the Trimeresurus species group.

Snake bite from mountain pit viper Local rear-fanged Colubridae species also secrete venom through the rear fangs but their mode of delivery is highly inefficient, rendering them incapable of delivering serious envenomations in a majority of cases. In Malaysia, snakes bites occur frequently in the northern part of the peninsular, but fatalities are rare. Also, it is often a misconception that snakes inject their venom directly into the blood stream.

Unless the fang hits a nerve, the venom enters primarily through the lymphatic system. Most cases of venomous snake bites on land occur from these species; Calloselasma Rhodostoma (accounts for the highest number of authenticated venomous snake bite in Peninsular Malaysia), Trimeresurus wagleri, Trimeresurus purpureomaculatus, Naja sumatrana and Naja kaouthia. Bites from the king cobra or Ophiophagus hannah are very rare but some cases are fatal. Sea snake bites are also very serious in nature and fatalies are not uncommon.

Other medically significant snakes include Bungarus candidus, Bungarus fasciatus, Calliophis species (coral snakes) and other Trimeresurus species of vipers. There is an overwhelming number of cases where the snake responsible was not identified, but generally, the systematic or topical effects of the envenomation will point in the approriate direction and proper treatment.

Elapids generally possess a neurotoxic venom; this attacks the nervous system of the body, causing numbness in the bitten area, paralysis, possible swelling and pain, and a culmunative effect that eventually leads to respiratory failure. Some species such as those from the Calliophis family may not even leave any topical effects or produce significant pain through their bite (also due to having very tiny fangs).

Neurotoxic venom is deadly because of the risk of cardiac arrest or paralysis, incapaciting a victim from getting help if alone. Viper venom, which is usually hemotoxic, cytotoxic or a combination of both, acts to destroy blood cells and tissue linings, causing massive hemorrhaging, inflamation, oedema and clotting defect. Moderate to immense pain will occur. Major symptons in most cases usually subside within a few days, but for extremely serious cases, amputations may be necessary if necrosis occurs. Viper venom is very damaging to tissue and causes excruciating pain as well as greatly weakening the immune system. Disfigurement or loss of body members is one of the greatests fears from a viper bite.

What to Do when Bitten by Venomous Snakes

Don't Panic - The key to surviving any snake bite in remote areas far from any hospital is to simpy stay calm. Having said that, it doesn't mean that the snake which just bit you is from a venomous species. Normally, in the case of a truly venomous snake, one will have to experience internal or topical symptoms within several minutes of the bite, depending on the type of venom (if) injected. Some examples of symptoms are; dizziness, paralysis, difficulty of breath, swelling, throbbing pain, uncoagulable bleeding and blurred vision.

In the case of an authentic envenomation by a dangerous snake, effects of venom are increased drastically by a person under immense stress and anxiety. Staying calm will allow you to think clearly and seek medical help in a controlled fashion. You probably have enough time to get to a car or find someone to bring you to a hospital as venom usually takes hours before the full effects reaches its pinnacle; provided you stay calm. Once you've calmed down, get to a government hospital if possible. Clinics and private hospitals should always be second choice as they lack the antivenin to deal with serious envenomations.

In Malaysia, only government hospitals stock antivenin as private clinics and hospitals cannot accomodate its high cost. Avoid all methods of torniquets, especially with viper bites. Arterial torniquets cut off blood flow and prevent venom from diluting itself through the system; Allowing the venom to disseminate itself from the bitten area may be more beneficial. A pressure bandage, which is a long and broad piece of lint, should be wrapped around the bitten area with Elapid bites.

Do not in any circumstances incise the wound or attempt sucking out the venom. There is a high risk of bacteria being introduced which causes infection and eventually grangrene. Avoid all forms of traditional remedies such as lime juice or ammonia salts as these hold no medical benefit and may worsen the condition. In most serious cases, antivenin treatment is the best remedy, with trained medical staff to monitor and deal with any allergic reactions that may ensue from antivenin administration. For neurotoxic bites, a ventilator is probably the most important form of treatment followed by antivenin.

Snake Bite Treament

Hospitalisation with antivenin treatment is the main course of action for serious envenomations. However, for midly moderate cases involving hemotoxic venom, anti-inflammatory medication both for oral and topical applications are effective, such as Voltaren (Diclofenac) or Feldene. The bitten area should be kept suspended upwards in the case of hands or fingers. A course of strong antibiotics is highly recommended along with plenty of rest. A line should be drawn with a pen about 2 cm away from the bitten area to monitor the progress of swelling.

Getting bitten by any local venomous species is a serious matter. For those that are not familiar with the venomous snake species found in Malaysia, always head to the hospital first and get a proper diagnosis if swelling or numbness occurs in the bitten area. And as always, the best care is left in the hands of experienced doctors in government hospitals, not private clinics.