Evidence of hearing loss and unrelated toxoplasmosis in a free‐ranging harbour porpoise (Phocoena phocoena)
Morell, Maria; Ijsseldijk, Lonneke L.; Berends, Alinda J.; Gröne, Andrea; Siebert, Ursula; Raverty, Stephen A.; Shadwick, Robert E.; Kik, Marja J.L.
(2021) Animals, volume 11, issue 11, pp. 1 - 15
(Article)
Abstract
Evidence of hearing impairment was identified in a harbour porpoise (Phocoena phocoena) on the basis of scanning electron microscopy. In addition, based on histopathology and immuno-histochemistry, there were signs of unrelated cerebral toxoplasmosis. The six‐year old individual live stranded on the Dutch coast at Domburg in 2016 and died a
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few hours later. The most significant gross lesion was multifocal necrosis and haemorrhage of the cerebrum. Histopathology of the brain revealed extensive necrosis and haemorrhage in the cerebrum with multifocal accumulations of de-generated neutrophils, lymphocytes and macrophages, and perivascular lymphocytic cuffing. The diagnosis of cerebral toxoplasmosis was confirmed by positive staining of protozoa with anti‐Toxo-plasma gondii antibodies. Tachyzoites were not observed histologically in any of the examined tis-sues. Ultrastructural evaluation of the inner ear revealed evidence of scattered loss of outer hair cells in a 290 μm long segment of the apical turn of the cochlea, and in a focal region of ~ 1.5 mm from the apex of the cochlea, which was compatible with noise‐induced hearing loss. This is the first case of concurrent presumptive noise‐induced hearing loss and toxoplasmosis in a free‐ranging harbour porpoise from the North Sea.
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Keywords: Encephalitis, Hair cell, Inner ear, Live stranding, Noise‐induced hearing loss, North Sea, Post‐mortem examination, Toxoplasma gondii, Animal Science and Zoology, veterinary(all)
ISSN: 2076-2615
Publisher: Multidisciplinary Digital Publishing Institute (MDPI)
Note: Funding Information: The animal was necropsied as part of the Stranding Research Programme of Utrecht University, commissioned by the Dutch Ministry of Agriculture, Nature and Food Quality, since 2016, and embedded under the Legal Research Tasks Nature & Environment Unit of Wageningen UR (project reference number WOT?04?009?045). Toxicological and life history analyses were funded by the Dutch Rijkswaterstaat as part of the Offshore Wind Ecological Programme (WoZEP 2016). The inner ear collection, preservation and analysis were funded by Rijkswaterstaat (WoZEP 2016) and the Natural Sciences and Engineering Research Council (NSERC) of Canada (Discovery and Accelerator grants RGPAS 446012?13 and RGPAN 312039?13). This publication was supported by Deutsche Forschungsgemeinschaft and University of Veterinary Medicine Hannover, Foundation, within the funding programme Open Access Publishing. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
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