looduskalender.ee

There has been much talk about vipers in newsmedia this year.

 

Vipers mostly flee from noise caused by humans. But if there is no opportunity to do so, they raise their head and give notice of their presence by hissing. They bite on being stepped on unexpectedly, or if harassed at too close quarters.

Habitats are always where water is nearby: lake shores, wet mixed forests, marshes, bogs, forest edges and even sea shores. Vipers are sedentary creatures and won’t move much further than 100 metres from their “summer homes“ in search of food and water. The will move from a place when disturbed, for instance when the owner family arrives at their summer house for a longer stay – but often “territory sharing“ works out peacefully. Of course there may be conflicts but it should be remembered that vipers retire rather than attack. They are quite tolerant creatures.

 

Five year old, sexually mature female vipers give birth in August. Five to ten or sometimes even more, young vipers can be born. The young vipers that embark on an independent life at once are around fifteen centimetres long; at the end of September when they head for winter quarters they have grown a little bit longer. having fed on butterfly caterpillars, earthworms, snails, insects, this summer’s little frogs. For each year they add a little more than ten centimetres to their length.

 

Years ago Erik Puura compiled a thorough overview of what to do in case of being bitten by a viper.

 

A comprehensive report written by professor Naomi Loogna was published in journal Terviseleht (Health Journal) in 2001: es http://www.terviseleht.ee/200128/28_uss.php; the question has also been discussed by Harri Jänes http://www.videvik.ee/479/ei.html.

Main points to remember:

General information

1. A viper only strikes when trodden on, hurt, touched, or disturbed in other ways.

2. In Estonia vipers are most often found on Saaremaa and Hiiumaa, and in Virumaa,and Läänemaa counties.

3. Viper venom is a clear, yellowish liquid, consisting of proteins, amino acids, minerals etc. The toxic effect is due to polypeptides and enzymes that degrade the red blood cells in blood and cause haemorrhages. The amount of secreted venom depends on the time since the viper’s latest hunting occasion. The venom is not particularly toxic, and so only occasional cases of viper bites are fatal. In about a third of the cases no venom enters the human victim.

4. The toxic effect on humans is at its maximum at about 30 minutes - 4 hours from the moment of the bite, decreasing after that. The effect of the venom depends on its amount, the victim’s general health and the location of the bite.  A bite is more dangerous in case of hot weather and when the bite is located in the face, neck or back. The most dangerous case is when a fang, and so also the venom, happens to strike a blood vessel.

5. In case of a bite two small, dot-shaped punctures about 0,5 – 1 cm apart can be seen; the bite itself is not particularly painful and reminds of a needle sting. Within a few minutes after the bite the pain may increase, within some twenty minutes a swelling may appear, the skin takes on a violet-purple colour and becomes sensitive. After about one hour there may be headaches, dizziness and nausea, sometimes also vomiting. There may be diarrhoea, breathlessness, a feeling of faintness, the skin may be covered with cold sweat, the victim may become restless and lose consciousness. The area of the bite can become red and swollen. The spot aches strongly. The swelling at the bite is at a maximum 48-72 hours after the bite. Blisters can occur. Lymph nodes near the bite enlarge. As the venom is absorbed changes can occur in the functions of several organs, for instance in the lungs. Kidney damage may occur. Haemorrhages and substances released from damaged tissues influence the clotting of the blood, and cause haemolysis. Face, lips or tongue of some victims can swell immediately after the bite.

6. The venom, as a foreign protein, may also cause an anaphylactic reaction (shock, throat swelling, bronchial spasms that expresses itself as a feeling of lack of air). Signs of shock: pale skin, pale to bluish lips, cold sweat, body tremors, a sense of weakness, thirst, a quick, weak pulse, restlessness, even loss of conscience.

7. Children and old people whose physical resistance is smaller show the general symptoms of the venom more clearly.

Treatment

8. The victim should be kept calm and brought into medical care as soon as possible. For reassurance: in Estonia no one has died from an viper bite within living memory http://foorum.maaleht.ee/viewtopic.php?pid=206; in the whole of Europe only a few cases of death are known from the last 10-20 years, the majority of them from the Mediterranean countries (Vipera ammodytes, long-nosed or sand viper), or the individuals have been oversensitive to viper venom. Hypersensitive persons, for instance those who are allergic to bee venom, certainly should be very cautious.

9. The smaller the victim, the greater the probable amount of venom per body weight basis and the risk of serious health effects.

10. In order to avoid sudden fall of blood pressure and collapse (unconsciousness due to the sudden decrease of blood supply to blood vessels in the brain) the victim should lie down. He/she shouldn’t move and the bitten limb shouldn’t be raised, since this favours fast transport of the poison in the body. The victim should be kept warm. A cooling compress may be placed on the bite.

11. If the bite is in an arm or leg, the limb can be put in a splint with whatever means that may be at hand, to slow down the flow of tissue fluids and so also the movement of the venom in the tissues. Rings and arm rings should be removed in advance. Many sources recommend that the victim should be given plenty of drink of any kind except alcoholic drinks, to accelerate the secretion of the venom through the kidneys and the sedentary tract. Plenty of hot coffee or tea is recommended. According to other recommendations however the effect of large amounts of drink hasn’t been proved. Obviously there may be cases and combinations of circumstances, for instance in connection with the victim’s general stand of health, when drinking hasn’t a positive effect.

12. Whether the victim needs an antivenom injection is decided by the medical staff. In newspaper Postimees an article was published in 2005  http://www.postimees.ee/110705/online_uudised/171039.phpabout a delayed antivenom injection and the consequences of the delay. On the other hand in 2004 the Estonian Health Care Board (now Health Board) sent out a press release stating that injections of antivenom in case of viper bites generally were not indicated since in one third of the viper bite cases no venom actually reaches a human victim, but the F(ab)2-type antivenom available in Estonia causes allergic reactions in about a tenth of the patients. There are no absolute indications for when to use antivenom. Relative indications are shock that doesn’t answer to treatment or is long-lasting, or fast spreading swellings in the facial or neck areas in combination with breathing difficulties. Adult patients should be observed in hospital for at least 6 hours, children for at least 24 hours. If during this time no significant swelling or general reaction occurs, the patient is dismissed. Recovery is faster the younger the patient. Those under 14 years recover within one to three weeks. For 2/3 of older patients the pain and swellings last for more than three weeks, for ¼ even up to nine months.

Wrong or dubious countermeasures

13. Tying a bitten limb with a band, belt, string or tourniquet does not stop the spread of the viper venom in the body; in addition it may hurt and damage tissues locally.

14. Attempts to suck out the venom from the wound by mouth are pointless, because due to the elasticity of the tissues the small bite wound closes immediately.

15. Cutting out or burning the bite spot damages blood vessels and nerves, subsequent infections may cause pus in the wound. The venom however moves so quickly in the body that it is not possible to remove it by removing tissue.

16. Painting the bite wound with an oxidising, that is, tissue-damaging, strongly violet solution of potassium permanganate is useless since it doesn’t reach the venom.

17. Drinking alcohol as an antidote is meaningless and even dangerous, since alcohol accelerates the dissipation of the venom in the organism and brings it quickly to the brain cells.

Avoiding bites

18. When moving in places where encounters with vipers can be feared, strong footwear should be worn, preferably high boots. The fangs of vipers can’t go through dense leather or rubber, but slip off or even break off.

Getting help

19. Suppose that you are in a remote place, for instance deep in a forest. Have you brought your mobile phone along, and is there network coverage? Can you describe where you are, or quickly reach a place to where you can direct rescuers? Or, if you are with a friend, how to behave? It would be useful to think it out for oneself, taking the information above in account. It is useful to try at once to find something cold to put on the bite area, for instance moss or water. The seriousness of the effects of the bite usually becomes evident within the first 10 minutes. The victim shouldn’t walk or run. Consulting a doctor even in case of a suspected bite is considered necessary.

I haven’t found any reports of cases where a lonely person, far from settlements and without a mobile phone, has been bitten by a viper, with subsequent severe shock or allergic reaction, whereupon the person would have had to decide how to act – whether to wait and observe the changes in health status or to try at once to start moving towards possible help?

It seems that in little Estonia no such combinations of circumstances have occurred - or does anyone know otherwise? In Great Britain there have been only 14 cases of death following viper bites since 1876, http://en.wikipedia.org/wiki/Vipera_berus , the most recent of them in 1975. In Sweden there is an average of 1300 viper bite incidents per year; in only 12% of these treatment in hospital was needed.

 

NB. The above is about vipers in Estonian conditions. While much is generally valid, behaviour and other characteristics can be different, and other venomous species can be present in other areas.