Viper envenomation in Central and Southeastern Europe: a multicentre study

Figures & data

Figure 1. Vipera berus (common European adder)(A) and Vipera ammodytes (nose horned viper)(B) (photo: M Brvar).

Figure 2. Central and Southeastern European countries included in the study [10]). Legend:

national data provided by the national poison centres.

local data provided by poison centres/toxicology departments

Table 1. Poison centres and toxicology departments included in the study, population covered by centres and departments, and reported viper bites (2018–2020).

Country (population)	Poison Centre / Toxicology Department	Population covered (% of county population)	Vipera berus	Vipera ammodytes	Unidentified viper	Total
Poland (38 million)	Poison Information Centre, Nofer Institute of Occupational Medicine, Łódź Clinic of Anesthesiology and Intensive Care, Toxicology Unit, Central Clinical Hospital of the Medical University of Łódź	4.6 million (12%)	12	0	1	13
Czech Republic (10.5 million)	Toxicological Information Centre, Department of Occupational Medicine, 1^st Faculty of Medicine, Charles University and General University Hospital, Prague	10.5 million (100%)	61	0	43	104
Slovakia (5.5 million)	National Toxicological Information Centre, University Hospital, Bratislava, Slovakia	5.5 mil (100%)	23	0	6	29
Hungary (9.7 million)	Department of Toxicology, Péterfy Hospital, Budapest	3 million (31%)	0	0	1	1
Slovenia (2.1 million)	Centre for Clinical Toxicology and Pharmacology, University Medical Centre Ljubljana, Ljubljana	2.1 million (100%)	7	22	12	41
Croatia (4.2 million)	Poison Centre, Institute for Medical Research and Occupational Health, Zagreb; University Hospital of Split, Split; University Hospital for Infectious Diseases, Zagreb	4.2 million (100%)	2	28	11	41
Serbia (7 million)	National Poison Centre, Military Medical Academy, Belgrade	7 million (100%)	10	14	32	56
Bulgaria (7 million)	Clinic of Toxicology, University Hospital for Emergency Medicine ”N.I.Pirogov”, Sofia	2 million (29%)	2	10	1	13
All countries (84.0 million)		38.9 million (46%)	117	74	107	298

Table 2. Incidence of viper bites and antivenom therapy in the service area of all participating poison centres and toxicology departments (38.9 millions) (2018–2020).

Vipera species	Bites per million population per year	Bites per million population per year treated with antivenom
All viper bites	2.55	1.07
Vipera berus	1.00	0.39
Vipera ammodytes	0.63	0.45
Unidentified viper	0.92	0.23

Table 3. Incidence of Vipera berus and Vipera ammodytes bites and antivenom treatment within their respective geographic distribution areas (2018–2020).

Vipera species	Bites per million population per year	Bites per million population per year treated with antivenom	Countries within the geographical distribution of Viper (population)
Vipera berus	1.00	0.39	Poland (Łódź), Czech Republic, Slovakia, Hungary (Budapest), Slovenia, Croatia, Serbia, Bulgaria (Sophia) (38.9 million)
Vipera ammodytes	1.61	1.16	Slovenia, Croatia, Serbia, Bulgaria (Sophia), (15.3 million)

Figure 3. Age distribution of patients bitten by vipers.

Figure 4. Monthly variation of viper bites.

Table 4. General characteristics of patients bitten by Vipera berus and Vipera ammodytes.

	Vipera berus (n = 117)	Vipera ammodytes (n = 74)	Odds ratio	95% confidence interval	P
Sex (male)	66 (56%)	49 (66%)	0.66	0.36–1.21	0.22
Age (mean ± standard deviation) (years)	38 ± 22	48 ± 24			0.01
Bite location
Arm	50 (43%)	48 (65%)	0.40	0.22–0.74	0.01
Leg	57 (49%)	24 (32%)	1.98	1.08–3.63	0.04
Other parts (belly, back)	2 (2%)	0 (0%)	Not applicable	Not applicable	0.52
Not specified	8 (6%)	2 (3%)	1.75	0.45–6.80	0.53

Table 5. Symptoms and signs, laboratory results, treatment and outcome in Vipera ammodytes and Vipera berus bites.

	Vipera berus (n = 117)	Vipera ammodytes (n = 74)	Odds ratio	95% confidence interval	P
Dry bite	11 (9%)	5 (7%)	1.43	0.48–4.30	0.60
Local pain	88 (75%)	67 (91%)	0.32	0.13–0.77	0.01
Oedema	91 (78%)	66 (89%)	0.42	0.18–1.00	0.05
Localized	42 (36%)	31 (42%)	0.78	0.43–1.41	0.45
Spreading	49 (42%)	35 (47%)	0.80	0.45–1.44	0.55
Bruising	63 (54%)	50 (68%)	0.56	0.31–1.03	0.07
Localized	33 (28%)	28 (38%)	0.65	0.35–1.20	0.20
Spreading	30 (26%)	22 (30%)	0.82	0.43–1.56	0.62
Vomiting	24 (21%)	15 (20%)	1.02	0.49–2.09	1.00
Diarrhoea	8 (7%)	6 (8%)	0.84	0.28–2.54	0.78
Decreased level of consciousness	22 (19%)	15 (20%)	0.91	0.44–1.89	0.85
Somnolence	21 (18%)	15 (20%)	0.86	0.41–1.80	0.70
Coma	1 (1%)	0 (0%)	NA	NA	1.00
Fever	3 (3%)	0 (0%)	NA	NA	0.28
Neurological symptoms	1 (1%)	2 (3%)	0.31	0.03–3.48	0.56
Cranial nerve palsies	1 (1%)	1 (1.5%)	0.63	0.04–10.22	1.00
Ataxia	0 (0%)	1 (1.5%)	0.00	NA	0.39
Tachycardia	25 (21%)	12 (16%)	1.40	0.66–3.00	0.45
Hypotension	25 (21%)	12 (16%)	1.40	0.66–3.00	0.45
Dyspnoea	4 (3%)	0 (0%)	NA	NA	0.16
Leukocytosis (> 10x10^9/L)	31 (27%)	30 (41%)	0.53	0.28–0.98	0.06
Thrombocytopenia (< 140x10^9/L)	14 (12%)	21 (28%)	0.34	0.16–0.73	0.01
Fatal outcome	0 (0%)	0 (0%)	NA	NA	1.00
Severity score (median, IQR)	1 (1–2)	2 (1–2)	NA	NA	0.10
Antivenom	45 (38%)	53 (72%)	0.25	0.13–0.46	0.01

NA: Not applicable

Table 6. Antivenoms used in Vipera berus, Vipera ammodytes and unspecified viper bites (2018–2020).

	ViperaTAb^®	Viper venom antitoxin	European viper venom antiserum	Bulbio snake venom antiserum	Viekvin^®	Viperfav^®
Vipera spp. raised against	Vipera berus	Vipera berus	Vipera ammodytes	Vipera ammodytes	Vipera ammodytes	Vipera berus, Vipera aspis, Vipera ammodytes
Countries	Czech Republic, Slovakia, Poland, Slovenia	Poland, Slovakia	Croatia	Bulgaria	Serbia	Slovenia
						Croatia
Vipera berus bites (45 patients treated with antivenom)	31 (69%)	3 (7%)	1 (2%)	1 (2%)	9 (20%)	0 (0%)
Number of antivenom doses per patient bitten by Vipera berus (number of patients)	1 (28)	1 (3)	2 (1)	2 (1)	1 (9)
	2 (3)
Vipera ammodytes bites (53 patients treated with antivenom)	7 (13%)	0 (0%)	19 (36%)	9 (17%)	13 (25%)	5 (9%)
Number of antivenom doses per patient bitten by Vipera ammodytes (number of patients)	1 (5)		1 (17)	1 (4)	1 (12)	1 (5)
	3 (2)		2 (2)	2 (4)	2 (1)
				3 (1)
Unspecified Vipera bites (27 patients treated with antivenom)	3 (11%)	0 (0%)	0 (0%)	0 (0%)	24 (89%)	0 (0%)
Number of antivenom doses per patient bitten by unspecified Vipera (number of patients)	1 (3)				1 (24)
Anaphylactic reaction (number of patients)	0	0	0	0	0	0
Serum sickness (number of patients)	0	0	0	0	0	0
Other complications (number of patients)	0	0	0	0	0	0

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