Abstract
Between 2010 and 2019, 2.432 gulls (Larus michahellis and Larus fuscus) with paretic syndrome were received at RIAS Wildlife Rehabilitation and Research Centre. The clinical signs included weakness, anorexia, paralysis, diarrhoea (flaccid cloacae), dyspnoea and, in some cases, death. Several biotic contaminants are among the potential cause of this syndrome: marine biotoxins, Clostridium botulinum, cyanotoxins and virus. This presentation compiles the results of the Clostridium botulinum and marine biotoxins analysis conducted at the French National Reference Centre for anaerobic bacteria and botulism, Pasteur Institute (Paris) and the Vigo Centre of the Spanish Oceanographic Institute, respectively.C. botulinum analyses were conducted in livers and intestines from 5 gulls with paretic syndrome symptoms admitted at RIAS Wildlife Rehabilitation and Research Centre. Samples were pooled in two groups according to the tissue and analysed by targeted Real Time Polymerase Chain Reaction (PCR) on neurotoxin genes after sample enrichment culture under anaerobic conditions. The presence of botulinum toxin was confirmed by a lethality test on mice (mouse bioassay). Mice were intraperitoneally injected with filtered supernatant of the culture. Paralytic shellfish toxins (PSTs) were analysed by Liquid Chromatography with Fluorescence Detection and Post-column Oxidation in samples from ten gull kidneys and in the cloacae contents from another gull. Domoic acid (DA) analysis was conducted following a procedure that involved a methanolic extraction and analysis by Liquid Chromatography coupled to High Resolution Mass Spectrometry. DA was analysed in twenty three gull samples: ten livers, ten intestines and three cloacae contents. PSTs and DA were not detected in any of the samples tested.Results obtained so far point to C. botulimum type C/D as the causative agent of the paretic syndrome in gulls.
Highlights
Between 2010 and 2019, 2432 gulls (1125 Larus michahellis and 974 L. fuscus) with paretic syndrome were received at RIAS Wildlife Rehabilitation and Research Centre of Ria Formosa (Olhão, Faro)
Whats the posible cause? Several biotic contaminants could be the potential cause of this syndrome: marine biotoxins, Clostridium botulinum, cyanotoxins and virus
Subcutaneous and intravenous fluid therapy Repeat fluid therapy for 24 or 48 hours until tube feeding is safe. The aim of this preliminary study was to evaluate if Amnesic Shellfish Toxins (Domoic acid, (DA)), Paralytic Shellfish Toxins (PSTs) or botulinum toxins could be the cause of the gulls paretic syndrome
Summary
Between 2010 and 2019, 2432 gulls (1125 Larus michahellis and 974 L. fuscus) with paretic syndrome were received at RIAS Wildlife Rehabilitation and Research Centre of Ria Formosa (Olhão, Faro). On admission 333 gulls were dead and 2099 were alive. Clinical signs: different degrees of ascendant flaccid paresis, weakness, anorexia, diarrhea (flaccid cloacae), dyspnoea and, in some cases, death. Dead animals were considered as paretic syndrome victims due to the presence of diarrhea, absence of injuries, the date of arrival concurring with a paretic syndrome outbreak and the necropsies findings. Gulls were classified in 5 different levels according to the symptoms severity (see Table). Several biotic contaminants could be the potential cause of this syndrome: marine biotoxins, Clostridium botulinum, cyanotoxins and virus. Other factors (starvation, abiotic contaminants, etc) could contribute to the gulls death.
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