<P> The Big Four are the four venomous snake species responsible for causing the most snake bite cases in South Asia (mostly in India). The Big Four snakes cause far more snakebites because they are much more abundant in highly populated areas . They are the Indian cobra (Raja Naga), common krait (Bungarus caeruleus), Russell's viper (Daboia russelii) and the Saw - scaled viper (Echis carinatus). </P> <P> The Indian cobra is a moderately venomous species, but has a rapid - acting venom . In mice, the SC LD for this species is 0.80 mg / kg and the average venom yield per bite is between 169 and 250 mg . Though it is responsible for many bites, only a small percentage are fatal if proper medical treatment and antivenom are given . The mortality rate for untreated bite victims can vary from case to case, depending upon the quantity of venom delivered by the individual involved . According to one study, it is approximately 15--20% . but in another study, with 1,224 bite cases, the mortality rate was only 6.5% . Estimated fatalities as a result of this species is approximately 15,000 per year, but they are responsible for an estimated 100,000 - 150,000 non-fatal bites per year . </P> <P> The common krait (Bungarus caeruleus) is often considered to be the most dangerous snake species in India . Its venom consists mostly of powerful neurotoxins which induce muscle paralysis . Clinically, its venom contains pre synaptic and postsynaptic neurotoxins, which generally affect the nerve endings near the synaptic cleft of the brain . Due to the fact that krait venom contains many presynaptic neurotoxins, patients bitten will often not respond to antivenom because once paralysis has developed it is not reversible . This species causes an estimated 10,000 fatalities per year in India alone . There is a 70 - 80% mortality rate in cases where there is no possible or poor and ineffective treatment (e.g., no use of mechanical ventilation, low quantities of antivenom, poor management of possible infection). Average venom yield per bite is 10 mg (Brown, 1973), 8 to 20 mg (dry weight) (U.S. Dept . Navy, 1968), and 8 to 12 mg (dry weight) (Minton, 1974). The lethal adult human dose is 2.5 mg . In mice, the LD values of its venom are 0.365 mg / kg SC, 0.169 mg / kg IV and 0.089 mg / kg IP . </P> <P> Russell's viper (Daboia russelii) produces one of the most excruciatingly painful bites of all venomous snakes . Internal bleeding is common . Bruising, blistering and necrosis may appear relatively quickly as well . The Russell's viper is irritable, short - tempered and a very aggressive snake by nature and when irritated, coils tightly, hisses, and strikes with lightning speed . This species is responsible for more human fatalities in India than any other snake species, causing an estimated 25,000 fatalities annually . The LD in mice, which is used as a possible indicator of snake venom toxicity, is as follows: 0.133 mg / kg intravenous, 0.40 mg / kg intraperitoneal, and about 0.75 mg / kg subcutaneous . For most humans, a lethal dose is approximately 40--70 mg . However, the quantity of venom produced by individual specimens is considerable . Reported venom yields for adult specimens range from 130--250 mg to 150--250 mg to 21--268 mg . For 13 juveniles with an average length of 79 cm, the average venom yield was 8--79 mg (mean 45 mg). </P>

Where does the most poisonous snake in the world live