Identifying Causative Agents of a Paretic Syndrome in Waterbirds in Southern Portugal

Paretic and paralyzing syndromes affecting wild birds are widely described in the literature, with outbreaks showing an increase in frequency and intensity worldwide during recent years. In the Iberian Peninsula, a paretic clinical picture without known etiology affecting mostly gulls has been repor...

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Main Authors: María V. Mena Casero, Andrew D. Turner, Begoña Ben-Gigirey, Ryan P. Alexander, Karl J. Dean, Robert G. Hatfield, Benjamin H. Maskrey, Christelle Mazuet, Kobey Karamendin, Rafael Mateo
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Toxins
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Online Access:https://www.mdpi.com/2072-6651/17/2/62
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author María V. Mena Casero
Andrew D. Turner
Begoña Ben-Gigirey
Ryan P. Alexander
Karl J. Dean
Robert G. Hatfield
Benjamin H. Maskrey
Christelle Mazuet
Kobey Karamendin
Rafael Mateo
author_facet María V. Mena Casero
Andrew D. Turner
Begoña Ben-Gigirey
Ryan P. Alexander
Karl J. Dean
Robert G. Hatfield
Benjamin H. Maskrey
Christelle Mazuet
Kobey Karamendin
Rafael Mateo
author_sort María V. Mena Casero
collection DOAJ
description Paretic and paralyzing syndromes affecting wild birds are widely described in the literature, with outbreaks showing an increase in frequency and intensity worldwide during recent years. In the Iberian Peninsula, a paretic clinical picture without known etiology affecting mostly gulls has been reported during the last few decades. This paretic syndrome (PS) affects waterbirds and is characterized by a set of signs of ascendent flaccid paralysis, dyspnea, and diarrhea at different levels of severity. This study presents the first macro-analysis of some potential etiological PS agents in wild birds in southern Portugal. Other possible etiologies of PS related to nutritional deficiencies and environmental pollutants were not studied but are also discussed here. A total of 571 samples, belonging to 377 individuals with (<i>n</i> = 336) and without (<i>n</i> = 41) PS signs, have been tested for seven different toxins groups (botulinum neurotoxin (BoNT), paralytic shellfish toxins (PSTs), domoic acid (DA), anatoxin-a (ATX-a), cylindrospermopsin (CYN), tetrodotoxins (TTXs), and microcystins (MCs)) and three viral infections (gull adenovirus (GA), Newcastle disease virus (NVD), and highly pathogenic avian influenza viruses (HPAIV)). Of all the birds tested for botulinum neurotoxin, those with PS signs were positive (100%) and those without PS signs were negative (0%), confirming an association between PS and botulism. Some samples were positive for PSTs and MCs, but the prevalence in birds with PS signs was not significantly higher (2.5% and 5.3%, respectively) than in birds without signs (5.4% and 5.4%, respectively). Two birds without PS signs were positive for highly pathogenic avian influenza virus. The presence of the rest of the toxins and viruses was negative for all the samples tested. Our results support the relevant contribution of botulinum neurotoxin in the PS outbreaks observed in several species of aquatic birds in the last decades in southern Portugal, suggesting it could be one of the main causes of mortality in waterbirds.
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spelling doaj-art-8a9dec536a6d49e8b2d60c4714a85d832025-08-20T03:12:19ZengMDPI AGToxins2072-66512025-01-011726210.3390/toxins17020062Identifying Causative Agents of a Paretic Syndrome in Waterbirds in Southern PortugalMaría V. Mena Casero0Andrew D. Turner1Begoña Ben-Gigirey2Ryan P. Alexander3Karl J. Dean4Robert G. Hatfield5Benjamin H. Maskrey6Christelle Mazuet7Kobey Karamendin8Rafael Mateo9Wildlife Rehabilitation and Research Center of Ria Formosa (RIAS), Rua do Parque Natural da Ria Formosa, 8700-194 Olhão, PortugalCentre for Environment Fisheries and Aquaculture Science (Cefas), The Nothe, Barrack Road, Weymouth DT4 8UB, UKCentro Nacional Instituto Español de Oceanografía (IEO-CSIC), Centro Oceanográfico de Vigo, 36390 Vigo, SpainCentre for Environment Fisheries and Aquaculture Science (Cefas), The Nothe, Barrack Road, Weymouth DT4 8UB, UKCentre for Environment Fisheries and Aquaculture Science (Cefas), The Nothe, Barrack Road, Weymouth DT4 8UB, UKCentre for Environment Fisheries and Aquaculture Science (Cefas), The Nothe, Barrack Road, Weymouth DT4 8UB, UKCentre for Environment Fisheries and Aquaculture Science (Cefas), The Nothe, Barrack Road, Weymouth DT4 8UB, UKCentre National de Référence des Bactéries Anaérobies et Botulisme, Institut Pasteur, Université Paris Cité, F-75015 Paris, FranceScientific and Production Center of Microbiology and Virology, 105 Bogenbay Batyr Street, Almaty 050010, KazakhstanInstituto de Investigación en Recursos Cinegéticos (IREC), Junta de Comunidades de Castilla-La Mancha (JCCM), Consejo Superior de Investigaciones Científicas CSIC)—Universidad de Castilla-La Mancha (UCLM), Ronda de Toledo 12, 13005 Ciudad Real, SpainParetic and paralyzing syndromes affecting wild birds are widely described in the literature, with outbreaks showing an increase in frequency and intensity worldwide during recent years. In the Iberian Peninsula, a paretic clinical picture without known etiology affecting mostly gulls has been reported during the last few decades. This paretic syndrome (PS) affects waterbirds and is characterized by a set of signs of ascendent flaccid paralysis, dyspnea, and diarrhea at different levels of severity. This study presents the first macro-analysis of some potential etiological PS agents in wild birds in southern Portugal. Other possible etiologies of PS related to nutritional deficiencies and environmental pollutants were not studied but are also discussed here. A total of 571 samples, belonging to 377 individuals with (<i>n</i> = 336) and without (<i>n</i> = 41) PS signs, have been tested for seven different toxins groups (botulinum neurotoxin (BoNT), paralytic shellfish toxins (PSTs), domoic acid (DA), anatoxin-a (ATX-a), cylindrospermopsin (CYN), tetrodotoxins (TTXs), and microcystins (MCs)) and three viral infections (gull adenovirus (GA), Newcastle disease virus (NVD), and highly pathogenic avian influenza viruses (HPAIV)). Of all the birds tested for botulinum neurotoxin, those with PS signs were positive (100%) and those without PS signs were negative (0%), confirming an association between PS and botulism. Some samples were positive for PSTs and MCs, but the prevalence in birds with PS signs was not significantly higher (2.5% and 5.3%, respectively) than in birds without signs (5.4% and 5.4%, respectively). Two birds without PS signs were positive for highly pathogenic avian influenza virus. The presence of the rest of the toxins and viruses was negative for all the samples tested. Our results support the relevant contribution of botulinum neurotoxin in the PS outbreaks observed in several species of aquatic birds in the last decades in southern Portugal, suggesting it could be one of the main causes of mortality in waterbirds.https://www.mdpi.com/2072-6651/17/2/62paretic syndromebotulism neurotoxintoxinsetiologydiagnosis
spellingShingle María V. Mena Casero
Andrew D. Turner
Begoña Ben-Gigirey
Ryan P. Alexander
Karl J. Dean
Robert G. Hatfield
Benjamin H. Maskrey
Christelle Mazuet
Kobey Karamendin
Rafael Mateo
Identifying Causative Agents of a Paretic Syndrome in Waterbirds in Southern Portugal
Toxins
paretic syndrome
botulism neurotoxin
toxins
etiology
diagnosis
title Identifying Causative Agents of a Paretic Syndrome in Waterbirds in Southern Portugal
title_full Identifying Causative Agents of a Paretic Syndrome in Waterbirds in Southern Portugal
title_fullStr Identifying Causative Agents of a Paretic Syndrome in Waterbirds in Southern Portugal
title_full_unstemmed Identifying Causative Agents of a Paretic Syndrome in Waterbirds in Southern Portugal
title_short Identifying Causative Agents of a Paretic Syndrome in Waterbirds in Southern Portugal
title_sort identifying causative agents of a paretic syndrome in waterbirds in southern portugal
topic paretic syndrome
botulism neurotoxin
toxins
etiology
diagnosis
url https://www.mdpi.com/2072-6651/17/2/62
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