First confirmation of Brachycladium atlanticum as aetiological agent of pulmonary pathologies in a common dolphin (Delphinus delphis).

The health of marine mammals is influenced by a great variety of natural stressors, including parasitic infestation, which can pose a risk to the individual and populational surveillance. The strandings of marine mammals give the opportunity to collect biological data from wild animals impossible to obtain in other circumstances. These events are an efficient resource to analyse, not only the cause of death, but also the diet, anatomy, genetics and parasitic infestations. During the rutinary necropsy of a common dolphin (Delphinus delphis) stranded in the Basque Coast, multiple noteworthy lung pathologies were observed, being especially significant a cystic formation full of pus in the right lung. Subsequent histopathological analysis of the cystic tissue revealed the presence of structures compatible with trematode eggs, together with different respiratory pathologies possibly related to the parasitic infestation. Molecular analysis of the eggs revealed homology with a partial sequence of the NADH dehydrogenase subunit 3 (nad3) gene and the internal transcribed spacer 2 (ITS2) region of Brachycladium atlanticum. The macroscopic and histopathological analysis performed in the stranded dolphin confirmed that the outcome of the animal may have been caused by a consumptive disease potentially linked to the pulmonary multispecific parasitic infestation compromising its survivability. As far as the authors are aware, this paper presents the first report of B. atlanticum in the lungs of a common dolphin, together with the histological description of a parasitic pneumonia caused by this trematode eggs and the first sequencing of the 28S rDNA gene for this species.