There are some 175 species of snakes in this region and 85 of these are at least mildly venomous.  Some, however, are truly dangerous.  Vipers (viperidae) are mostly tissue toxic causing ulcerations and muscle damage.  Some are also hemotoxic, causing blood cell damage and bleeding.  The Russell’s viper is the most dangerous species in this group as it can cause severe hemorrhaging.  The Malayan pit viper is also a hazard in rubber plantations as it bites without warning and can cause serious muscle destruction.  There are a whole group of green and not so green pit vipers which are venomous and tissue damaging.  The Elapidaea (cobras, kraits, coral and sea  snakes) cause paralysis and can be fatal with arrest of respiratory muscles.  Sea snakes are very dangerous in that they can also cause paralysis and severe muscle damage.  They are present in the Gulf of Siam and Indian Ocean but rarely bite humans.  It is best to consider any snake that you meet as dangerous.  Snake bites in Thailand range from 10-12/100,000.  This can be compared to 4/100,000 in North America and 600/100,000 in West Africa.  Most snake bites could have been easily avoided.  Trying to catch a venomous snake is the most common cause.  There are now less that 20 human deaths from snake bite in the Kingdom and this is due to fewer snakes due to environmental encroachment and the availability of treatment.  Antivenins are manufactured by the Thai Red Cross in Bangkok and generally available where needed.  First aid for a snake bite consists in applying an elastic bandage to the limb as you would do for a sprained ankle.  This slows spread of venom through lymphatic channels under the skin.  The patient is then transported to the nearest hospital.  Incision of wounds, sucking wounds, applying constrictive tourniquets will result in more damage and should be avoided.  Only paracetamol (Tylenol) is used for pain relief.  If there is respiratory paralysis (cobra or krait bite), mouth to mouth breathing or respiratory aid such an Ambu Bag is used during transport to the hospital.  Antivenins are made from horse serum and should only be administered intravenously by qualified staff.  They are never given before there is evidence of intoxication.  Many snake bites, even from venomous snakes, are just bites and do not inject venom.  Snakes bite in defense and have no interest in eating humans. The venom is also a digestive juice and they do not usually waste it on a human who is to big to eat.  Thailand also has 3 species of pythons that can be huge and very powerful.  They are not poisonous but are able to kill man by constriction, and if it is a small man, eat him too.