2024 - Viper bite

What is it about ?

The peliad viper (Vipera berus) is the only species of poisonous snake found in Belgium. Its venom can penetrate deep into tissue. The severity of the bite depends on the amount of venom injected. It can also be a question of dry or white bite (without injection of venom).

The venom of the viper contains several substances. Some damage tissue, others have an influence on blood circulation and coagulation. The symptoms can be very varied. Most often, the symptoms remain localized at the site of the bite. But some victims also have severe generalized symptoms. The bite of a viper is fatal in 1 to 2 in 100 people.

What is its frequency?

In Belgium, viper bites are rare. In our regions, the presence of the viper is limited to the Haute-Meuse basin and the Antwerp Campine. The animal fears the man.

The Poison Control Center receives a maximum of five calls per year for a possible viper bite. Every year, a few cases are wrongly attributed to the peliad viper due to confusion with the grass snake (Natrix natrix) or the smooth crown snake (Coronella austriaca). Non-poisonous, these species are also found in our regions.

The manifestations are limited to local symptoms in 3 out of 4 victims. On the other hand, one in 4 people presents more serious symptoms of envenomation. In recent years, no viper bites with fatal consequences have been reported in our country.

How to recognize it?

Local swelling and severe pain develop at the bite. The skin turns a dark purple color, and small blood deposits form around the bite. After 2 to 3 days, these symptoms slowly decrease. General symptoms can also occur. The most important are:

digestive disorders (nausea, vomiting, stomach aches and diarrhea);
cardiovascular problems (fast heartbeat, low blood pressure (hypotension), cardiac arrhythmias, coagulation problems leading to spontaneous onset of blues, etc.);
difficulty in breathing;
blockage of the kidneys (decreased urine production);
(severe) allergic reaction components of the venom, such as a generalized rash, associated with itching, and even shock;
central nervous system disorders with headache, low level of consciousness and convulsions.

Some problems do not appear until later. This can lead to (severe) wound infection. Blisters may form and the skin may turn black and die (necrose). Affected skin may remain discolored for several months. Sometimes the venom causes sensory disturbances in the limbs for several months.

How is the diagnosis made?

The doctor will inspect the bite and try to assess the degree of envenomation. A “dry” or “white” bite causes only moderate pain at the bite site, with no swelling. Injecting a small to moderate amount of the venom can already cause very severe pain with swelling (edema) and sometimes also blisters around the bite site.

In the hours following the bite, there may be a risk of a drop in blood pressure and generalized symptoms such as general weakness, stomach pain and vomiting.

In the event of severe envenomation, the edema extends to the trunk and it forms effusions of blood on the level of the skin, but also of the digestive tract and the respiratory tracts. This is a very serious and potentially fatal situation.

What can you do ?

It is not indicated to attempt to aspirate venom from the wound or blood, even with a suction device. This is because the venom penetrates deep into the tissues. The following measures, on the other hand, are very important:

Calm the victim, as agitation accelerates the spread of the venom;
Disinfect the bite: wash it first with soapy water, then use disinfectant;
Secure the affected limb with a splint and elevate it. This will relieve pain and limit muscle movement;
Remove anything that can tighten (rings, bracelets, tight clothes or tight shoes, etc.);
Paracetamol, if available, relieves pain. Avoid aspirin and anti-inflammatory drugs, as they have an effect on blood clotting;
Get the victim to the hospital as quickly as possible.

If you are at risk of a viper bite, it may be appropriate to have cortisone tablets on hand. They could reduce the risk of a serious allergic reaction, although their effectiveness is not scientifically proven.

The installation of a compression bandage is not recommended, given the risk of aggravation of the lesions.

What can your doctor do?

All viper bites can be treated in the hospital. In the meantime, the doctor can disinfect the bite and possibly give a dose of cortisone. At the hospital, the victim is monitored for at least 6 hours. Children are more vulnerable to the effects of the venom. A child who is bitten by a viper must be hospitalized and receive intensive follow-up.

During the first few days, the most important thing is to hydrate it and monitor its water and salt balance. Intensive support for vital functions is sometimes required, as is the administration of red blood cells, platelets, coagulation factors, etc. In the event of signs of infection, antibiotics may be administered.

Pain relief is paramount, paracetamol is the first choice. Anti-inflammatory drugs and aspirin should be avoided.

In case of moderate to severe envenomation, antivenom should be administered as soon as possible. The latter is sometimes combined with cortisone to prevent allergic reactions.

The doctor will check the vaccination status against tetanus and, if necessary, administer a booster dose, possibly supplemented with anti-tetanus antibodies.

After treatment with the antivenom or in case of severe symptoms, the doctor will schedule a check-up 1 to 2 weeks after the bite.

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