Exotic venomous snakebites in Switzerland reported to the National Poisons Information Centre over 22 years.

OBJECTIVE: The private keeping of exotic venomous snakes is legally permitted in Switzerland. The aim of the present study was to characterise the epidemiological and clinical features of bites by exotic venomous snakes over a period of 22 years in Switzerland. METHODS: We included all calls related to exotic snakebites recorded at the Swiss National Poisons Information Centre (Tox Info Suisse) from 1997 to 2018. Exclusion criteria comprised indigenous snakes, non-venomous exotic snakes such boas or pythons, clinical courses incompatible with a snakebite or calls from abroad. Follow-up information was graded according to the Poisoning Severity Score. RESULTS: Within the study period, 1,364 calls related to snakebites were recorded at Tox Info Suisse; 148 (11%) cases were attributed to exotic venomous snakes and fulfilled the study criteria. A total of 112 (98%) of 114 patients with medical follow-up information exhibited sufficient causality between exposure and clinical effects. Only adult patients were affected. The median age was 40 years (range 16-71) and the male gender was predominant (n = 136, 92%). Viperidae were involved in 87 (78%) and Elapidae in 25 (22%) patients. Overall, the main affected body part was the hand (89 patients, 79%). In the majority of the patients the clinical course was mild (46, 41%) or moderate (40, 36%), in a lower proportion asymptomatic (6, 5%) or with severe symptoms (20, 18%). No fatalities were reported in the study period. Severe symptoms were observed after elapid bites in six patients (24%) and after viper bites in 14 patients (16%). Besides local effects, neurological disorders after elapid bites and haematological disorders after viper bites were most frequently reported. Antivenom was administered in 24% (27 patients: 18 Viperidae, 21% and 9 Elapidae, 36%; 5 patients (4%) required multiple doses), overall, with good resolution of symptoms. CONCLUSION: Exotic snakebite is a rare occurrence in Switzerland but has led to medically relevant morbidity, sometimes requiring antivenom treatment. Over half of the envenomed patients required symptomatic or specific treatment. No fatalities or bites in children were reported.

Indigenous venomous snakebites in Switzerland: analysis of reports to the National Poisons Information Centre over 22 years.

INTRODUCTION: Two venomous snakes, the asp viper (Vipera aspis) and the common adder (Vipera berus) are native to Switzerland. Bites by both vipers cause mainly local effects, but systemic envenomation is possible. METHODS: We analysed all calls concerning indigenous venomous snakebites recorded at the Swiss National Poisons Information Centre between 1997 and 2018, including all cases with identification by a herpetologist, and/or with compatible symptoms and circumstances of the exposure. RESULTS: During the study period, 1,364 cases concerned snakebites. One third (466; 34%) were attributed to indigenous vipers. In 243 (52%) patients, medical follow-up information was available, with good causality between exposure and symptoms in 219 (90%) patients. Vipera aspis was identified in 77 of the cases (35%), Vipera berus in 54 (25%), and not further specified vipers in 88 (40%). In over two thirds of the 219 cases (155, 71%) adult patients were affected (male 109, female 46; median age 43 years [range 16-90]). Sixty-four patients were children (male 47, female 16; median age 11 years [range 1.3-15.9]). The highest occurrence of bites was in the summer months. In the majority of patients, the clinical course was mild (94; 43%) or moderate (80; 36%); a lower proportion was either asymptomatic (17; 8%) or exhibited severe symptoms (28; 13%). There were no fatalities reported. The most frequent symptoms were local effects at the bite site with mild (100; 46%) to moderate (56; 25%) swelling, pain (65; 30%) and redness (51; 23%). Gastrointestinal symptoms including nausea (31; 14%), vomiting (47; 22%) and abdominal pain (25; 11%) were also common. Other systemic symptoms included cardiovascular effects (e.g., hypotension (20; 9%) or shock [6; 3%]), neurotoxicity (e.g., visual impairment [5; 2.3%]) and haematotoxicity (e.g., coagulopathy [11; 5%]). Seven (3.2%) patients developed anaphylactic reactions. Antivenom was administered in only 20% (24 with moderate and 19 with severe symptoms) with good resolution of symptoms. The mean duration of hospitalization was 2 days (0-12 days). CONCLUSION: Snakebites in Switzerland can result in severe symptoms, sometimes necessitating antivenom treatment.