VENOMOUS SNAKES IN ASIA: KRAITS, RUSSELLS VIPER AND THE SAW-SCALED VIPER

VENOMOUS SNAKES IN ASIA

saw-scaled viper

There are a lot of deaths and injuries from venomous snake bites in Asia. In India about 20,000 people are killed each year from snake bites, more than a thousand times more than die from tiger attacks. In some parts of Southeast Asia the death rate from snakes bites is 38 per 100,000 people, the highest in the world The snake bite rate is so high because many poor farmers sleep on the ground, walk around barefoot, and work in rice fields that attract rats and they in turn attract snakes.

Poisonous snakes found in Thailand include: A) three species of krait: (1) the Malayan krait or blue krait; 2) banded krait; and 3) the red-headed krait); B) four species of cobra: (1) monocled cobra; 2) Indochinese spitting cobra; 3) Sumatran cobra or equatorial spitting cobra; plus the king cobra (which belongs to a different subfamily than cobras); C) four species of coral snakes including the blue coral snake and small-spotted coral snake; D) two species of sea kraits (the yellow-lipped sea krait and black-banded sea krait); E) 12 species of sea snakes; and F) about 20 species and subspecies of viper and pit viper including the Russelĺs viper, chain viper, Malayan pit viper, yellow-lipped pit viper, Cardamom Mountains green pit viper, Kanburi pit viper, mangrove pit viper, brown-spotted green pit viper, Pope's pit viper, Phuket pit viper, Siamese peninsula pit viper, Wirots palm viper, and Wagler's pit viper.

The Big Four refers to the four venomous snake species responsible for causing the most snake bite cases in South Asia (mostly in India). They are: 1) the Indian cobra, Naja naja, probably the most famous of all Indian snakes; 2) the common krait, Bungarus caeruleus; 3) Russell's viper, Daboia russelii; and 4) the saw-scaled viper, Echis carinatus.

Asian pit vipers are two to five feet long, and found throughout Asia. Their bite causes severe tissue damage but rarely result in death. The fangs of the pit viper have been compared to "four-inch masonry nails."

The sharp-nosed pit viper — one hundred pace snake — reaches lengths of five feet. Found in southern Vietnam, Taiwan and China, it is the most toxic of the Asian pit vipers. A bite causes immediate swelling, tissue damage and internal bleeding and may be fatal. Its nickname refers to number of paces a victim takes before he dies. There is an antivenin. The blue coral snake is also referred to a one hundred pace snake. Native to Southeast Asia, it is 1.2 to 1.4 meters long and mostly blue in color except for bright orange markings below its head and tail. Highly venomous, it has venom glands running up and down nearly a third of its body. The snake, however, has a mild disposition and few fatal bites to humans have been recorded.

The white-lipped pit viper is a mostly arboreal snakes that is 60 to 100 centimeters long and lives in Southeast Asia. This slender-bodied snake is one of several green pit vipers from Southeast Asia. It has a wide rounded head and hangs down from trees head first at night. It waits for prey to come its way. When prey come within range it quietly pulls its head back and strikes. The bite is painful but the venom relatively mild and rarely fatal to humans. Females give birth to 10 to 11 young.

Cobras, See Separate Article

Asian Snake Bite Remedies

In many places antivenim is not available and people rely on remedies made by local healers. In some cases medicine man who specialize in snake bites do nothing more than recommend that their patients recite a few mantras and make a small sacrifice. The technique has a very high success rate since most of the bites are attributed to non-venomous snakes.

Some remedies are said to be very effective. In Jodagette, near Bangalore, a healer named G. Swami Rao makes a snakebite remedy that local people swear by. Antony Gomes, a professor at the University of Calcutta, studied the medicine. He injected one group of rats with snake venom and 50 percent of them died. He injected another group with venom and gave them Rao's remedy none of them died. When Gomes tried to get a hold of plants used in the remedy, Rao refused to provide them out of fear the professor would steal his secret remedy.

Other people prefer taking preventive measures. In Malaysia, some farmers keep geese because they make a big noise whenever they see a snake. Local herb specialist prescribe "Rauwolfia", a root with a chemical used to treat high blood pressure.

Krait

Kraits are among the world's deadliest snakes. They are found in southern Asia. Their bite causes rapid onset of sleepiness and numbness. The mortality rate is 50 percent even with treatment from antivenin. American soldiers in Vietnam used to call the krait the 5 Step, meaning that if you got bitten by a krait you would take five steps and then die Kraits belong to the same family of snakes as cobras. They are often strikingly colored. Most are black with white and yellow bands. They sometimes get into to battles with king cobras. In most cases they lose and are eaten by the much larger snake.

The common krait (also known as Indian krait or Blue krait) is found in the jungles of the Indian subcontinent and is a member of the "big four", species inflicting the most snakebites in India. The average length is 0.9 meters (2 ft 11 in) but they can grow to 1.75 meters (5 ft 9 in). Males are longer with proportionately longer tails. Colouration is generally black or bluish black, with about 40 thin, white crossbars which may be indistinct or absent anteriorly. [Source: Wikipedia]

Kraits inhabit a wide variety of habitat in its range: fields, low scrub jungle as well as inhabited areas. They are known to take up residence in termite mounds, brick piles, rat holes and also inside houses. It is fond of water and is frequently found in it or within proximity to a water source. These snakes prey on other snakes, lizards, frogs, rats, and mice. They will devour their young being cannibalistic in nature. [Ibid]

Krait Attacks and Venom

Generally docile and unaggressive during the day, the krait may become aggressive at night if threatened. During the day it is sluggish and rolls its body into a loose coiled ball, keeping its head well-concealed. In balled condition, the snake allows considerable handling, however, over handling often instigates bites. At night the snake is very active, escapes by hissing loudly, or keeping still, occasionally biting the source of the annoyance. When agitated, it will coil up with head concealed, body flattened, and make jerky movements. It may also lift its tail. Reluctant to bite, but when it does bite, it typically bites and holds on for awhile, which enables it to inject considerable amounts of venom. [Source: Wikipedia]

The Indian krait's venom consists mostly of powerful neurotoxins which induce muscle paralysis. Kraits are nocturnal and seldom encounter humans during daylight hours, so incidents occur mainly at night. There is frequently little or no pain from a krait bite and this can provide false reassurance to the victim. Typically, victims complain of severe abdominal cramps, accompanied by progressive paralysis. Once bitten, the absorption of the venom into the victim can be considerably delayed by applying a pressure bandage to the bite site (using about the same tension as one uses for a sprained ankle) and immobilising the area. This allows for gentle transport to medical facilities, where the venom can be treated when the bandage is removed. As there are no local symptoms, a patient should be carefully observed for signs of paralysis and treated urgently with antivenom. It is also possible to support bite victims via mechanical ventilation, using equipment of the type generally available at hospitals. Such support should be provided until the venom is metabolised and the victim can breathe unaided. If death occurs it takes place approximately 6 to 8 hours after the krait bite. Cause of death is general respiratory failure, i.e. suffocation.

Often in rainy season the snakes come out of their hiding places and find refuge on dry places inside a house. If bitten by it in sleep the victim seldom comes to know as the bite feels more like an ant bite or a mosquito bite. The victim may be dead before he even wakes up. One such case was recently reported in Indore, an accent instructor of English language was bitten by it inside his house, and was declared dead on arrival at the hospital. A clinical toxicology study gives an untreated mortality rate of 70 to 80 percent.

In June 2001, Ananova reported: “The monsoon has hit Nepal with extra venom this year, with 18 people dying of snake bites since the onset of the seasonal rains in the west of the country. Among the latest victims are a couple who died after being bitten by a highly poisonous krait snake while they were asleep in their village. The couple were treated with traditional medicines in their village as there was no time to take them to a hospital, the Kathmandu Post says. Even if bite victims can reach hospital quickly, there is no guarantee that they can survive the venom of snakes like the krait and cobra, which are found in the Terai lowland region of western Nepal. [Source: Ananova, June 29, 2001]

Many-Banded Krait

banded krait

The many-banded krait is so named because it has on its body broad black bands mixed with white narrow bands in between, looking like many bands. It is a mid-sized snake of about 1.9m maximum length. The width of the white band at the center of its back is far narrower than the black bands. Only a very few of them have their black bands turning into light brown or fragmented, making the body brownish black. They can be identified from the tail of a single scale or the big scale at the center of the back. It has a small but non-triangular head, and has no pit. The white plum blossom snake (Lycodon ruhstrati ruhstrati), its kinsman, has broader but irregular white bands. (Source: Yangmingshan National Park Headquarters, Taiwan]

The species is nocturnal and slow in movement. Frogs, lizards, fish and other snakes are their staple foods. They are often found in Myanmar, south China and Taiwan. They live in humid environments on the mountainside and cultivated lands. They are occasionally seen on Yangmingshan. Mating during August and September, they lay about 3-20 eggs each time between the end of spring and summer. It takes about 1.5 months to hatch these eggs.

The many-banded krait is quite mild and seldom attacks humans spontaneously. However, it becomes very sensitive when frightened. It has a pair of big grooved-teeth about 5mm long and two pairs of smaller grooved-teeth. It is the most venomous of all venomous snakes in Taiwan. Its venom is neurotoxic, victims seldom feel great pain, just like an ant’s bite. Though there are tooth marks, the wound does not swell and bleeds very little, thus making people often neglect the bite. Therefore, extreme caution is needed. A bite will turn into something approaching fatal-respiratory failure-when one feels sleepy. This usually takes 30 minutes to 2 hours. Its venom first attacks the connection between nerves and muscles, and then blocks the transmission of neurons, causing the striated muscles to fail to contract and respiration to be paralyzed. Therefore, victims should seek immediate medical attention when eyelids become heavy or when they feel chest discomfort. Though it is only the number three human attacker in Taiwan, it is the number two human killer. The mortality rate of victims is as high as 18-24 percent .

Russell's Viper

Russell's viper (daboia) is found in Asia throughout the Indian subcontinent, much of Southeast Asia, southern China and Taiwan. It reaches lengths of 1½ meters and is marked with dark-brown blotches, edged with white, on a lighter background. They have a well deserved reputation for aggressiveness and striking without warning. Russell's viper venom causes internal bleeding. Bites from this snake are relatively common and the mortality rate is moderate. There is an Antivenin. The venom has a clotting agent that useful in the treatment of hemophilia.

The Russell's viper is named in honor of Patrick Russell (1726-1805), a Scottish herpetologist who first described many of India's snakes. It genus (daboia) is named after the Hindi name meaning "that lies hid", or "the lurker." It is a member of the big four snakes in India and arguably the most deadly snake in the world. It is responsible for causing the most snakebite incidents and deaths than any other venomous snakes, in part because they are widely distributed and commonly found in places with large human populations.

Russell’s viper is distinguished by it light brown body with three rows of dark edged brown blotches down its back. The head is flattened, triangular and distinct from the neck. The crown of the head is covered with irregular, strongly fragmented scales. There are two pairs of chin shields, the front pair of which are notably enlarged. The two maxillary bones support at least two and at the most five or six pairs of fangs at a time: the first are active and the rest replacements. The fangs attain a length of 16 mm in the average specimen. The color patterns of the body consists of a deep yellow, tan or brown ground color, with three series of dark brown spots that run the length of its body. Each of these spots has a black ring around it, the outer border of which is intensified with a rim of white or yellow.

Russell's vipers are mostly found in open, grassy or bushy areas, but may also be found in second growth forests (scrub jungles), on forested plantations and farmland. They tend to avoid dense forests and most common in plains, coastal lowlands and hills of suitable habitat. This species is often found in highly urbanized areas and settlements in the countryside, the attraction being the rodents commensal with man. As a result, those working outside in these areas are most at risk of being bitten. It should be noted, however, that it does not associate as closely with human habitation as cobras and kraits.

The Russell's viper is a sit and wait predator that relies on camouflage to hide its presence from unaware prey. Itlfeeds primarily on rodents but will eat just about anything, including rats, mice, shrews, squirrels, land crabs, scorpions and other arthropods. Juveniles feed on lizards and forage actively. As they grow and become adults, they begin to specialize in rodents. Indeed, the presence of rodents is the main reason they are attracted to human habitation. Juveniles are known to be cannibalistic. Although this genus does not have the heat-sensitive pit organs common to the Crotalinae, it is one of a number of viperines that are apparently able to react to thermal cues, further supporting the notion that they too possess a heat-sensitive organ. The identity of this sensor is not certain, but the nerve endings in the supranasal sac of these snakes resemble those found in other heat-sensitive organs.

Russell's Viper Aggressiveness and Venom

Russell's vipers are mostly nocturnal forager but during cool weather they often become more active during the day. Adults are reported to be persistently slow and sluggish unless pushed beyond a certain limit, after which they become aggressive. Juveniles, on the other hand, are generally more nervous.

When threatened Russell's vipers form into a coil comprised of a series of S-loops, hisses and strikes hard, often lifting its body off the ground in the process. When it goes int attack-defense mode it raises the first third of the body and produce a hiss that is supposedly louder than that of any other snake. When striking from this position, it can exert so much force that even a large individual can lift most of its body off the ground in the process. These snakes are strong and may react violently to being picked up. The bite may be a snap, or they may hang on for many seconds.

The quantity of venom produced by individual specimens is considerable. Reported venom yields for adult specimens range from 130 to 250 milligrams to to 21 to 268 milligram. For most humans, a lethal dose is approximately 40 to 70 milligrams. Venom toxicity and bite symptoms in humans vary within different populations and over time.

Envenomation symptoms begin with pain at the site of the bite, immediately followed by swelling of the affected extremity. Bleeding is a common symptom, especially from the gums and in the urine, and sputum may show signs of blood within 20 minutes post-bite. There is a drop in blood pressure, and the heart rate falls. Blistering occurs at the site of the bite, developing along the affected limb in severe cases. Necrosis is usually superficial and limited to the muscles near the bite, but may be severe in extreme cases. Vomiting and facial swelling occur in about one-third of all cases. Kidney failure (renal failure) also occurs in approximately 25-30 percent of untreated bites. Severe disseminated intravascular coagulation also can occur in severe envenomations. Early medical treatment and early access to antivenom can prevent and drastically reduce the chance of developing the severe/potentially lethal complications.

Severe pain may last for two to four weeks. Locally, it may persist depending on the level of tissue damage. Often, local swelling peaks within 48 to 72 hours, involving both the affected limb and the trunk. If swelling up to the trunk occurs within 1 to 2 hours, massive envenomation is likely. Discoloration may occur throughout the swollen area as red blood cells and plasma leak into muscle tissue. Death from septicaemia, kidney, respiratory or cardiac failure may occur 1 to 14 days post-bite or even later. In India, the Haffkine Institute prepares a polyvalent antivenin that is used to treat bites from this species.

A study in The Lancet journal showed that out of a sample of people bitten by Daboia russelii who survived, 29 percent of them suffered severe damage to their pituitary glands, which later resulted in hypopituitarism. Because this venom is so effective at inducing thrombocytopenia, it has been incorporated into an in vitro diagnostic test for blood clotting that is widely used in hospital laboratories. This test is often referred to as Dilute Russell's viper venom time (dRVVT). The coagulant in the venom directly activates factor X, which turns prothrombin into thrombin in the presence of factor V and phospholipid.

Some herpetologists believe that the Russell's viper is so successful as a species and has such a fearful reputation within its natural environment, another snake has even come to mimic its appearance. Superficially, the rough-scaled sand boa has a color pattern that often looks a lot like that of a Russell's vipers even though it is completely harmless.

Russell's Viper Attacks in India

In April 2012, The Times of India reported: “A young snake-catcher of Telugu Palayam was admitted to Coimbatore Medical College Hospital (CMCH) on Monday afternoon after being bitten by a Russell's viper. He is battling for life in hospital. According to hospital authorities and police, R Ravi (32) belonged to CGV Nagar in Telugu Palayam. He works with a textile mill as supervisor while his wife R Anitha is a constable with Big Bazaar Street Police Station. On Monday morning, Ravi found his five-year-old daughter amongst a group of children in the locality looking curiously at a set of bricks kept at a construction site. The children told him that a snake was hiding inside the bricks. When Ravi investigated, he did find the Viper in between the bricks. He caught the snake and put it inside a gunny bag. When he attempted to tie the gunny bag, the snake bit his left hand. [Source: The Times of India, April 24, 2012]

In May 2011, The Times of India reported from Bangalore: “Affluent residents of Coconut Grove now pay less for water and more to catch poisonous snakes in their compounds. Some households shell out Rs 600 just to get one snake caught. This ward is among the most populous, with population exceeding 90,000 in Census 2011. Houses in this area near K R Puram remain surrounded by vacant sites which are not maintained and a breeding ground for venomous snakes. [Source: The Times of India, May 18, 2012]

On May 6, the area witnessed the first snakebite death. Lakshmi B, a 26-year-old Nepali domestic help, who went to pluck flowers in an apartment garden, died within hours of being bitten by a snake. She was two months pregnant. Women in the apartment rushed her to nearby hospital but in vain. Not many autorickshaws ply these narrow, bumpy roads as drivers refuse to come there. Those who do demand high fares. Finally, when the women got help, Lakshmi was already dead.

"I was told there are snakes here but I hadn't realized they'd up killing us. We're leaving for Nepal. I just hope there are no more deaths,'' said her husband Bijay Bahadur, a security guard. Her son Prashanth, 2, still weeps for his mother, little knowing she won't come back. After this incident, parents keep their kids locked indoors. But, the threats of snakes continue. Every home has an anecdote to share.

"We've seen three huge snakes within our compound in the past five months'' says Lakshmi Siju, a mother of two. The last time, on Saturday, it was a 4.5-foot Russel Viper. "I'd just come in after checking the water level in the sump. From the window, I spotted the snake in our compound, just a few feet from the sump,'' she said.

"Even after Lakshmi's death, the corporation has done nothing to get the vacant sites cleaned. We're get them cleaned regularly at our expense. We also pay Rs 150 per house for road and layout development now. It's a shame on the BBMP. Our lady corporator never takes calls. It's always her husband who answers. They've done nothing to help us," says an angry Saroj Ramnani, 67, the oldest resident of this layout.Expanding beyond city limits, we have also encroached into the natural habitat of snakes, mostly in newly added areas.

Saw-Scaled Viper

The saw-scaled viper(carpet viper) causes more human fatalities that any other snake. Reaching lengths of two feet and ranging from West Africa to India, it has a bite that causes severe bleeding and fever. The saw-scaled viper is mostly found in the dry regions of Africa, the Middle East, Pakistan, India and Sri Lanka. They have a characteristic threat display, rubbing sections of their body together to produce a "sizzling" warning sound. Eight species are currently recognized. There is an antivenin.

Saw-scaled vipers are small, nasty, and ill-tempered. Belonging to the Echis genus, they are particularly aggressive at night and like to live in the sand. They are quite common in some parts of Africa. The famous early man hunter Dr. Louis Leakey clubbed more than 50 of the venomous snakes around his camp in six weeks. One reason they are so deadly is they are relatively common tropical rural areas that lack modern medical facilities. Most victims are bitten after dark when these snakes are active.

Relatively small in size, the adults are never larger than about 90 cm (35 in) in length. The head is short, wide, pear-shaped and distinct from the neck. The snout is short and rounded, while the eyes are relatively large and set well forward. The crown is covered with small, irregular, imbricate scales, which may be either smooth or keeled.The body is moderately slender and cylindrical. The dorsal scales are mostly keeled. However, the scales on the lower flanks stick out at a distinct 45̊ angle and have a central ridge, or keel, that is serrated (hence the common name). The tail is short and the subcaudals are single.

All members of this genus have a distinctive threat display, which involves forming a series of parallel, C-shaped coils and rubbing them together to produce a sizzling sound, rather like water on a hot plate. The proper term for this is stridulation. As they become more agitated, this stridulating behavior becomes faster and louder. These snakes can be fierce and will strike from the position described above. When doing so, they may overbalance and end up moving towards their aggressor as a result, most unusual behavior for a snake. Little is known about their diets, which are reported to be extremely varied, and may include items such as locusts, beetles, worms, slugs, spiders, scorpions, centipedes, solifugids, frogs, toads, reptiles (including other snakes), small mammals and birds.

The venom of Echis species consists mostly of haemotoxin. Most of these species have venom that contains factors that can cause a consumption coagulopathy and defibrination, which may persist for days to weeks. This may result in bleeding anywhere in the body, including the possibility of an intracranial hemorrhage. The latter classically occurs a few days following the bite.

Venom toxicity varies among the different species, geographic locations, individual specimens, sexes, over the seasons, different milkings, and, of course, the method of injection (subcutaneous, intramuscular, or intravenous). Consequently, the toxicity values for Echis venoms differ significantly. The amount of venom produced also varies. Reported yields include 20 to 35 milligrams of dried venom from specimens 41 to 56 centimeters in length, six to 48 milligrams (16 milligrams average) from Iranian specimens and 13 to 35 milligrams of dried venom from animals from various other localities. Yield varies seasonally, as well as between the sexes: the most venom is produced during the summer months and males produce more than females.

Russell's Viper and Saw-Scaled Viper Attacks in Sri Lanka

Nadia Fazlulhaq wrote in the Sunday Times of Sri Lanka: “It was a dream come true for Lal Dissanayake and wife Chamindani when they recently moved into the house they built in Battaramulla along with their little bundle of joy, three-year-old Thinugi...Their happiness of moving into their new house was short-lived as Chamindani’s life was felled by a saw-scaled viper. [Source: Nadia Fazlulhaq, Sunday Times of Sri Lanka, October 30, 2011]

Recalling the events of that fateful day in September 2011 Mr. Dissanayake said, “Usually our front gate is open when I come home. But that day it was closed and as I drove up in the car my wife came running out to open it for me. Suddenly she shouted that an insect had bitten her. I saw it was no insect but a small Veli Polanga and I killed it. As I knew it was poisonous I rushed her to the National Hospital.”

Despite getting her to the hospital by 8.30 p.m, Mr. Dissanayake said her treatment started only around 11.30 p.m. When she complained of a headache she was given paracetamol. When she started vomiting blood and was finding it difficult to breath she was taken to the neurological Intensive Care Unit (ICU) as there was no room at the Medical ICU. However the following day when her condition became critical she was taken to the Medical ICU he said.

“On Wednesday at around 3 a.m. a nurse informed me that my wife had passed away. I never thought that having been at the hospital for two days she would die. Our little girl thinks that a snake took her mother away and she would be returning soon,” he told the Sunday Times with tear-filled eyes. After her death it was found that a plot of unoccupied land bordering their house had been breeding these deadly creatures — with 12 vipers being found when it was cleared.

Padmakumara Jeewandara (60) from Malabe, was fortunate to survive a Russel’s Viper bite after receiving treatment at the Sri Jayawardenapura Hospital ICU for three days. Mr. Jeewandara was also bitten while he was closing the gate to his house around 10.30 p.m on October 16. The Russel’s Viper that attacked his ankle was hiding in the grass when he trod on it. Several viper bites had been reported from the area, the Sunday Times learns

In another incident, a university student boarded in Nugegoda was bitten by a viper when he had gone to the Gamsabha Junction to buy some dinner. He was immediately rushed to the Kalubowila Hospital and was still undergoing treatment.Well known herpetologist Dr. Anslem de Silva, who did the first epidemiological study on snake bites in 1965 said Sri Lanka recorded the highest number of deaths from snake bites during the latter part of the ‘70s.

The Russell’s viper bite can cause abnormal bleeding and delayed clotting blood stained vomit, bleeding from the rectum and gums. Bleeding into the brain or other organs may be fatal, he said. The patients may also exhibit neurological manifestations, such as drooping of eye lids, visual disturbances, double vision and difficulty in moving the eye balls.

Other Snakes

In Southeast Asia, a small snake feeds on mudskippers and small crabs. They can close their nostrils underwater and have a venom particularly good at killing their prey. They also have a special valve on their throats that closes when they underwater and allow the snake to open is mouth for hunting with taking water.

A third kind of snake has developed tentacles on its nose that may help find prey in muddy water. There is also a kind of frog, the only one its kind in the water, that can tolerate salt water in its skin.

Image Sources: Wikimedia Commons

Text Sources: National Geographic, Natural History magazine, Smithsonian magazine, Wikipedia, New York Times, Washington Post, Los Angeles Times, Times of London, The Guardian, Top Secret Animal Attack Files website, The New Yorker, Time, Newsweek, Reuters, AP, AFP, The Economist, BBC, and various books and other publications.

Last updated May 2014

VENOMOUS SNAKES IN ASIA: KRAITS, RUSSELLS VIPER AND THE SAW-SCALED VIPER