Epidemiology of snakebite in Europe: Comparison of data from the literature and case reporting

A review of bites by non-front-fanged snakes (NFFS) of Europe

Non-front-fanged snakes (NFFS) have long been overlooked by snake venom research, likely due to most of them being considered non-medically relevant for humans. The paucity of information about composition and activities of NFFS venoms and oral secretions makes it difficult to assess whether a given species can inflict medically significant bites. Here, we provide a review of the information currently available about the symptoms/signs elicited by bites from European NFFS, aiming to offer a foundation for understanding the threat they pose in terms of snakebite. Despite an overall limited amount of available data for most of the considered taxa, the genus Malpolon is notable for its capacity to cause local and systemic envenoming, including neurotoxic symptoms. Bites by other genera like, Hemorrhois, Hierophis, Natrix, Platyceps, Telescopus, and Zamenis are mainly associated with local symptoms, but the extent of their medical significance remains unclear. Our findings suggest that, although bites from European NFFS generally cause only mild effects, the potential occurrence of systemic effects from some species cannot be ruled out. Considering the above, any bite by European NFFS should receive professional medical evaluation in order to ensure patient safety and appropriate management, as well as detailed documentation facilitating construction of an accurate medical risk profile for the species.

Venom-induced myocarditis: An unusual case attributable to Vipera aspis bite

Venomous bites are medical emergencies that may result in life-threatening clinical effects. Cardiovascular complications are uncommon but they can be dangerous if not early detected and treated. Cerebral and myocardial infarction are described; myocarditis as consequence of viper envenomation in humans are very rare, almost anedoctal. We present the case of a 33-year-old man, working as keeper in a reptile zoo, who arrived after a viper bite of the Vipera aspis species, on the left wrist. The patient presented with clouded sensorium, edema of the lips and tongue, rapidly worsened with angioedema, and the need for oro-tracheal intubation; severe thrombocytopenia and anemia were treated with transfusions of platelet, plasma and red blood cells. The left hand and arm worsened, with compartment syndrome, treated with surgical fasciotomy. From a cardiological point of view, the patient presented a sudden drop in blood pressure, electrocardiographic anterior and infero-lateral ST depression, pericardial effusion and hypokinesia of the interventricular septum on echocardiography, and a significant increase in troponin T. Cardiac magnetic resonance imaging confirmed the myocarditis, with the presence of septal and anterior intramyocardial edema in T2 weighted sequences, with prolonged T2 time at T2 mapping analysis, without late gadolinium enhancement areas. Cardiological and general clinical conditions gradually improved only after the antivenom was administred. This is one of the rare cases of viper bite myocarditis with echocardiographic and magnetic resonance imaging documentation in Europe; it emphasizes the importance of identifying uncommon complications of venomous snake-bites and the prompt administration of antivenom, even though snake bites are less frequent at our latitudes.

A Guide to the Clinical Management of Vipera Snakebite in Italy

The genus Vipera encompasses most species of medically significant venomous snakes of Europe, with Italy harbouring four of them. Envenomation by European vipers can result in severe consequences, but underreporting and the absence of standardised clinical protocols hinder effective snakebite management. This study provides an updated, detailed set of guidelines for the management and treatment of Vipera snakebite tailored for Italian clinicians. It includes taxonomic keys for snake identification, insights into viper venom composition, and recommendations for clinical management. Emphasis is placed on quick and reliable identification of medically relevant snake species, along with appropriate first aid measures. Criteria for antivenom administration are outlined, as well as indications on managing potential side effects. While the protocol is specific to Italy, its methodology can potentially be adapted for other European countries, depending on local resources. The promotion of comprehensive data collection and collaboration among Poison Control Centres is advocated to optimise envenomation management protocols and improve the reporting of epidemiological data concerning snakebite at the country level.

Viper envenomation in Central and Southeastern Europe: a multicentre study

INTRODUCTION

Snakebite incidence varies across Europe. However, there is limited research from Central and Southeastern Europe. These regions are notable for the presence of the common European adder (Vipera berus) and the more venomous nose-horned viper (Vipera ammodytes). No standard European antivenom protocol exists. The aim was to assess the epidemiology and treatment of viper bites in this region, focusing on a comparison of bites from Vipera berus and Vipera ammodytes.

METHODS

We conducted a prospective multicenter study in Central and Southeastern Europe from 2018 to 2020. This study included poison centres and toxicology-associated hospital wards in Poland, the Czech Republic, Slovakia, Hungary, Slovenia, Croatia, Serbia, and Bulgaria. The following data were collected: age, gender, Vipera species, snakebite site, clinical picture, laboratory results, Audebert's clinical severity grading score, and antivenom therapy.

RESULTS

The annual incidence of viper bites in Central and Southeast Europe was estimated at 2.55 bites per million population. Within their respective geographical distribution areas, the incidence of Vipera ammodytes bites (1.61 bites per million population) was higher than Vipera berus bites (1.00 bites per million population). Patients bitten by Vipera ammodytes more frequently reported local pain and developed thrombocytopenia. Antivenom treatment was more commonly administered in Vipera ammodytes bites (72%) compared to Vipera berus bites (39%). The incidence of Vipera ammodytes bites treated with antivenom within its geographical distribution area was three times higher than Vipera berus bites treated with antivenom (1.16 bites per million population versus 0.39 bites per million population). No deaths were reported.

CONCLUSIONS

The estimated incidence of viper bites in Central and Southeastern Europe is at least 2.55 per million population. Vipera ammodytes bites are more common and severe, characterized by higher frequencies of pain and thrombocytopenia. Antivenom is needed more often for Vipera ammodytes bites. It is vital that enough European Medicines Agency-approved Vipera ammodytes antivenom is produced and offered affordably.

Envenomation by Vipera aspis in Piedmont (Italy): A report of three cases, including one case with neurological symptoms

This report describes three cases of human envenomation by the asp viper (Vipera aspis) in Piedmont, north-west Italy. A woman was bitten on the ankle while she was hiking and two herpetologists received bites on the hand while they were manipulating the animals. In the first case, the victim presented severe systemic symptoms (abdominal pain, vomiting, diarrhea) that required treatment with two vials of antivenom and hospitalization for one week. In the second case, the patient manifested neurological symptoms (blepharoptosis, ophtalmoplegia); he was treated with antivenom and discharged after five days. In the third case, the patient was bitten by a juvenile viper and showed only local symptoms (edema and bruising). All patients reported prolonged functional impairment after discharge from hospital. Although uncommon, envenomation by Vipera aspis can cause severe consequences that require immediate management and antivenom administration. These cases highlight the importance of obtaining better knowledge of the intraspecific variability of venoms and its clinical significance, as well as of the factors that determine the severity of snakebite injuries.

An antivenin resistant, IVIg-corticosteroids responsive Viper Induced Thrombocytopenia

In this case report the hospital management of an acute, severe thrombocytopenia in a 57-year-old man in the north-east of Italy is reported. Thrombocytopenia developed immediately after the viper bite, despite the absence of clinical signs of envenomation. No hemorrhage, ecchymoses or other signs of coagulopathy developed during the hospitalization; two doses of antivenin FAB–Fragments had no effect on thrombocytopenia, which instead responded promptly to intravenous immunoglobulins (IVIg) and glucocorticoids. Direct and indirect anti-platelet antibodies against anti-GP IIb/IIIa and Ia/IIa were detected during the treatment and turned negative after 20 weeks. The rationale of such off-label treatment is the interpretation of the thrombocytopenia as a venom-induced immune thrombocytopenia which led to splenic sequestration of platelets. To our knowledge, there is no literature about venom-induced immune thrombocytopenia against GP IIb/IIIa and Ia/IIa protein in European countries and subsequent response to IVIg and corticosteroids.

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Thrombocytopenia is a known effect of viper envenomation.

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Antivenin FAB–Fragments may be ineffective for thrombocytopenia.

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Venom induced immune thrombocytopenia against GP IIb/IIIa and Ia/IIa.

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A treatment based on IVIg and corticosteroids led to a prompt recovery of a severe antivenin-resistant Venom induced thrombocytopenia.

Acute Exposure to European Viper Bite in Children: Advocating for a Pediatric Approach

Viper bite is an uncommon but serious cause of envenoming in Europe, especially in children. Our study aim is to better describe and analyze the clinical course and treatment of viper bite envenoming in a pediatric population. We retrospectively reviewed 24 cases of pediatric viper bites that were admitted to the Pediatric Emergency Department and the Pediatric Intensive Care Unit of the Bambino Gesù Children Hospital in Rome between 2000 and 2020. Epidemiological characteristics of the children, localization of the bite, clinical and laboratory findings, and treatment approaches were evaluated. The median age of the patients was 4.2 years, with male predominance. Most cases of viper bite occurred in the late summer. Most patients required admission to the ward for prolonged observation. The most common presenting signs were pain, local oedema, and swelling. Patients with a high severity score also had a significantly higher white blood cell count and an increase of INR, LDH, and CRP levels. No fatality was reported. Viper bite envenomation is a rare pediatric medical emergency in Italy but may sometimes be severe. A new pediatric severity score may be implemented in the screening of children with viper bites to favor a selective and prompt administration of antivenom.

Snakebite Envenomation and Heart: Systematic Review

Snakebite envenomation is a neglected tropical disease which can result in morbidity and mortality. Cardiac implications are poorly understood due to the low frequency of cardiotoxicity combined with a lack of robust information, as snakebites commonly occur in remote and rural areas. This review aims to assess cardiovascular implications of snakebite envenoming and proposes an algorithm for screening of cardiovascular manifestations. A systematic review was performed and 29 articles relating to cardiovascular involvement in snakebite envenomation were selected. Cardiovascular involvement seems to be rare and includes a wide spectrum of outcomes, such as myocardial infarction, ventricular dysfunction, hypotension, cardiac arrest, and myocarditis. In a significant proportion of the cases analyzed (24.39%), the cardiovascular manifestations had major consequences (cardiac arrest, myocardial infarction, malignant ventricular arrhythmias, or death). Clinical monitoring, physical examination, and early electrocardiogram should be considered as key measures to detect cardiovascular involvement in patients with evidence of systemic illness.

Oliveira I, Rimbault C, A. Cerni F, Wen FH, Sachett J, Sartim MA, Laustsen AH, Monteiro WM. Current Knowledge on Snake Dry Bites

Snake 'dry bites' are characterized by the absence of venom being injected into the victim during a snakebite incident. The dry bite mechanism and diagnosis are quite complex, and the lack of envenoming symptoms in these cases may be misinterpreted as a miraculous treatment or as proof that the bite from the perpetrating snake species is rather harmless. The circumstances of dry bites and their clinical diagnosis are not well-explored in the literature, which may lead to ambiguity amongst treating personnel about whether antivenom is indicated or not. Here, the epidemiology and recorded history of dry bites are reviewed, and the clinical knowledge on the dry bite phenomenon is presented and discussed. Finally, this review proposes a diagnostic and therapeutic protocol to assist medical care after snake dry bites, aiming to improve patient outcomes.

Upper limb compartment syndrome after a viper bite in a child: A case report

The occurrence of compartment syndrome after a viper bite is a rare phenomenon and its treatment remains controversial. We report the case of an 11-year-old boy who developed compartment syndrome of the right upper limb following a viper bite. Decompression by fasciotomy was performed urgently with a good outcome. Surgical decompression for compartment syndrome following a viper bite is not a common treatment according to the literature. Fast access to care and antivenom administration seem to be effective at treating the compartment syndrome without recourse to fasciotomy.

Incidence and mortality due to snakebite in the Americas

BACKGROUND

Better knowledge of the epidemiological characteristics of snakebites could help to take measures to improve their management. The incidence and mortality of snakebites in the Americas are most often estimated from medical and scientific literature, which generally lack precision and representativeness.

METHODOLOGY/PRINCIPAL FINDINGS

Authors used the notifications of snakebites treated in health centers collected by the Ministries of Health of the American countries to estimate their incidence and mortality. Data were obtained from official reports available on-line at government sites, including those of the Ministry of Health in each country and was sustained by recent literature obtained from PubMed. The average annual incidence is about 57,500 snake bites (6.2 per 100,000 population) and mortality is close to 370 deaths (0.04 per 100,000 population), that is, between one third and half of the previous estimates. The incidence of snakebites is influenced by the abundance of snakes, which is related to (i) climate and altitude, (ii) specific preferences of the snake for environments suitable for their development, and (iii) human population density. Recent literature allowed to notice that the severity of the bites depends mainly on (i) the snake responsible for the bite (species and size) and (ii) accessibility of health care, including availability of antivenoms.

CONCLUSIONS/SIGNIFICANCES

The main limitation of this study could be the reliability and accuracy of the notifications by national health services. However, the data seemed consistent considering the similarity of the incidences on each side of national boundaries while the sources are distinct. However, snakebite incidence could be underestimated due to the use of traditional medicine by the patients who escaped the reporting of cases. However, gathered data corresponded to the actual use of the health facilities, and therefore to the actual demand for antivenoms, which should make it possible to improve their management.

Alpha-gal is a possible target of IgE-mediated reactivity to antivenom

BACKGROUND

Antivenoms are mammalian immunoglobulins with the ability to neutralize snake venom components and to mitigate the progression of toxic effects. Immediate hypersensitivity to antivenoms often occurs during the first administration of these heterologous antibodies. A comparable clinical situation occurred after introduction of cetuximab, a chimeric mouse-human antibody, for cancer treatment. The carbohydrate epitope galactose-alpha-1,3-galactose, located on the Fab region of cetuximab, was identified as the target responsible for IgE reactivity.

OBJECTIVE

To investigate whether serum IgE antibodies directed to the α-gal epitope are associated with hypersensitivity to equine antivenoms.

METHODS

Antivenoms were screened for α-gal epitopes via immunoblot and in comparison with cetuximab and pork kidney by IgE reactivity assays. Basophil activation tests were used to investigate reactivity to antivenoms in samples from 20 patients with specific IgE antibodies to α-gal and 10 controls. Additional IgE detection, IgE inhibition, ImmunoCAP inhibition, and skin prick tests were performed using samples from selected patients.

RESULTS

Both antivenoms and cetuximab induced positive skin prick test results in patients with sIgE to α-gal. Alpha-gal epitopes were detected by immunoblotting on antivenoms. Measurements of IgE reactivity and ImmunoCAP inhibition indicated that the antivenoms contained lower α-gal contents than cetuximab. Deglycosylation assays and IgE inhibition tests confirmed that IgE-mediated reactivity to antivenom is associated with α-gal. Antivenoms, pork kidney, and cetuximab activated basophils from patients with IgE to α-gal.

CONCLUSION

Alpha-gal is a potential target of IgE-mediated reactivity to equine antivenom and a possible cause of the high incidence of hypersensitivity reactions during the first application of equine antivenom.

Nomenclatural instability in the venomous snakes of the Bothrops complex: Implications in toxinology and public health

Since nomenclature is intended to reflect the evolutionary history of organisms, advances in our understanding of historical relationships may lead to changes in classification, and thus potentially in taxonomic instability. An unstable nomenclature for medically important animals like venomous snakes is of concern, and its implications in venom/antivenom research and snakebite treatment have been extensively discussed since the 90´s. The taxonomy of the pitvipers of the Bothrops complex has been historically problematic and different genus-level rearrangements were proposed to rectify the long-standing paraphyly of the group. Here we review the toxinological literature on the Bothrops complex to estimate the impact of recent proposals of classification in non-systematic research. This assessment revealed moderate levels of nomenclatural instability in the last five years, and the recurrence of some practices discussed in previous studies regarding the use of classifications and the information provided about the origin of venom samples. We briefly comment on a few examples and the implications of different proposals of classifications for the Bothrops complex. The aim of this review is to contribute to the reduction of adverse effects of current taxonomic instability in a group of medical importance in the Americas.

Venomous snakebites in children in southern Croatia

This retrospective study represents observation of 160 children and adolescents aged up to 18 years that experienced venomous snakebites in southern Croatia and were treated in the Clinical Department of Infectious Diseases in the University Hospital Centre Split from 1979 to 2013. The main purpose of this research was to determine the epidemiological characteristics, clinical presentation, local and general complications, and received treatment. Most bites occurred during warm months, from early May to late August (80%), mostly in May and June. Upper limb bites were more frequent (59%) than lower limb bites (40%). Out of the total number of poisoned children, 24% developed local, and 25% general complications. The most common local complications were haemorrhagic blisters that occurred in 20% children, followed by compartment syndrome presented in 7.5% patients. The most dominated general complication was cranial nerve paresis or paralysis, which was identified in 11.2% patients, whereas shock symptoms were registrated in 7% children. According to severity of poisoning, 9.4% children had minor, 35% mild, 30.6% moderate, and 24.4% had severe clinical manifestation of envenomation. Only one (0.6%) child passed away because of snakebite directly on the neck. All patients received antivenom produced by the Institute of Immunology in Zagreb, tetanus prophylaxis as well, and almost all of them received antibiotics, and a great majority of them also received corticosteroids and antihistamines. Neighter anaphylactic reaction nor serum disease were noticed in our patients after administrating antivenom. A total of 26% children underwent surgical interventions, and incision of haemorrhagic blister was the most common applied surgical treatment, which was preformed in 15.6% patients, while fasciotomy was done in 7.5% subjects. All of our surgically treated patients recovered successfully.

Epidemiology of envenomations by terrestrial venomous animals in Brazil based on case reporting: from obvious facts to contingencies

Background

Envenomation remains a neglected public health issue in most tropical countries. A better understanding of the epidemiology of bites and stings by venomous animals should facilitate their prevention and management. This study aimed to explore the benefits that could be derived from the compulsory notification of cases as it is now routinely practiced in Brazil.

Methods

The Brazilian Notifiable Diseases Information System (SINAN) was consulted online for the 2001–2012 period on all envenomations by venomous terrestrial animals. We studied the incidence, severity, number of deaths, gender, season of accident and time between the accident and hospital consultation.

Results

In total, 1,192,667 accidents and 2,664 deaths from terrestrial venomous animals (snakes, scorpions, spiders, bees and caterpillars) were reported in Brazil during these 12 years, the circumstances of which are detailed in this study. Most envenomations and deaths were caused by snakebites and scorpion stings. However, incidence and mortality showed high regional variations. During this period, the steady and parallel increase of the cases from all the species resulted from several factors including the human population increase, gradual improvement of data collection system and, probably, environmental and socioeconomic factors affecting in a different way the incidence of envenomation by each zoological group and by region.

Conclusion

Mandatory reporting of cases appears to be a useful tool to improve the management of envenomations. However, local studies should be continued to account for the variability of accident circumstances and refine measures necessary for their management.