Weever fish envenomation - analysis of enquiries to the UK National Poisons Information Service (NPIS) from 2004-2011

Background: The Weever fish (Echiichthys vipera) is one of very few aquatic creatures found around the coast of the UK that can cause significant envenomation likely to require attendance at hospital. Symptoms can include severe pain at the puncture site, dizziness, sweating, headache, chest pain and swelling of the affected limb.

Case series: Enquiries to the NPIS relating to Weever fish stings in the period April 2004 – April 2011 were analysed to examine the severity of symptoms reported and which treatments were recommended, particularly in relation to the time of the enquiry post exposure.

Discussion: Over this 7-year period, 45 enquiries were received with a high proportion, as expected, being stings to the feet. Sixteen enquiries (36%) were referred to NPIS within 24 hours of exposure, 12 of these (27%) being referred within the first 5 hours. Twenty enquiries (44%) were received more than one day following exposure, 9 of these within 5 days, a further 7 within 2 weeks and surprisingly 4 enquiries were received more than 3 weeks post exposure, one of these being after 10 weeks. Of the exposures referred within 24 hours, 6 patients complained of both pain and swelling at the site of envenomation, some referring to the pain as severe. Four patients reported pain alone and another 3 only swelling. A further 3 callers reported visible oedema of the affected limb. One patient complained of having difficulty breathing. Hot water immersion was recommended as treatment in 9 of these cases, the majority being patients who presented within 5 hours of exposure. The remainder received advice regarding appropriate analgesia and supportive care. Of those patients referred more than 24 hours post exposure, 7 were still experiencing pain at the site, 2 of these were 3 weeks after exposure. A further 8 still had swelling, one with an oedematous limb. Nausea, chest pain, headache, sweating, dizziness and skin reactions were also reported by some patients. Subcutaneous spines were evident in one patient two weeks after being stung. Treatment in these patients was generally supportive with appropriate analgesia, antihistamines and antibiotics.

Conclusions: Weever fish toxin is protein-based and readily denatured by hot water. The mainstay of treatment is to immerse the affected limb in hot water as soon as possible after envenomation and until the pain has eased. Appropriate antibiotic and analgesic treatment can be instigated at the same time. The high proportion of patients (44%) presenting well after the effective treatment interval yet still with appreciable pain and discomfort leads us to recommend that medical attention should be sought immediately after Weever fish envenomation.