Reuss' "European cobras" - clinical picture of the envenomed patients by the lowland populations of the Balkan adder (Vipera berus bosniensis)

Malina Tamás; University of Debrecen, Department of Botany, Egyetem tér 1, H-4032 Debrecen, Hungary.
Krecsak Laszlo; Eötvös Loránd University, Department of Systematic Zoology and Ecology, Pázmány Péter s. 1/C, H-1117 Budapest, Hungary.
Jelić Dušan; State Institute for Nature Protection, Trg Mažuranića 5, 10000 Zagreb, Croatia.
Maretić Tomislav; University Hospital "Dr Fran Mihaljević", Department of Infectious Disease, Mirogojska 8, 10000 Zagreb, Croatia.

Puni tekst:
(Engleski)

Tip članka:
Kongresni sažetak

Sažetak
In 1927, Reuss described several new adders from the Vipera berus populations in the valley of River Sava, which he classified into the new subgenus of Vipera, Mesocoronis. Later he included in the subgenus all adders from the Balkans (now V. b. bosniensis) and claimed that these possess neurotoxic venom. Reuss noted that V. b. bosniensis, native to the Balkans, is one of the most dangerous European vipers, as their bite can easily lead to systemic neurotoxicity, characterised by ptosis, ophthalmoplegia with complete ocular immobility, diplopia, speaking difficulties, dyspnoea, and lower limb paralysis; therefore he named these snakes "European cobras". This taxon reaches its northernmost distribution in lowlands of south-western Hungary. The aim of our survey was to investigate the pertinence of the statements from the literature, and test whether these bites rather cause systemic neurotoxicity than cardiovascular disorders. Our clinical study is based on 53 snakebite cases, which occurred in south-western Hungary and the northern parts of Croatia. Incidents were collected retrospectively from paper based and electric patient databases of four SW Hungarian hospitals (Somogy and Zala County) and two Croatian hospitals (Zagreb and Slavonski Brod). With regard to the bite severity, 9.4% of the cases were asymptomatic, 45.3% mild, 22.6% moderate and 22.6% severe with average hospitalisation of 2.75 days. No death was recorded in the surveyed regions in the last decades, although one fatality occurred in the past 60 years in SW Hungary. According to our results, envenomings by these adders rather resulted in mild (50.9%) and moderate (35.8%) local symptoms than those which are inflicted by V. b. berus; however the possibility of systemic neurotoxicity is high (22.6%) combined to a quite similar antihaemostatic venom effects as in V. b. berus envenomings. The rapid onset of neurotoxicity (mainly cranial nerve paralysis, i.e. ptosis, diplopia, focusing impairment, blurred vision, vertigo) can progress in dyspnoea and lower limb paralysis at V. b. bosniensis bites. Other unusual systemic symptoms were fluctuating arterial hypertension, drowsiness, and hypokalaemia; this latter being first documented at envenomings by European Vipera. The most common systemic symptoms were gastrointestinal disorders (45.3%), ECG changes (35.8%) and hypotension (32.1%). Laboratory results reveal mainly leucocytosis, while anaemia is a much less frequent sign of envenomings than at the bites caused by V. b. berus. The clinical picture and process of the envenomings by these lowland populations of the Balkan adders differ significantly from the bites of the Central and Northern European adder populations, which support their distinction as a separate taxonomic entity.

Ključne riječi
Snakebite, Cranial nerve disturbances; Ptosis, Dyspnoea; Hypokalaemia