This article reports the results of necropsy, parasitologic, microbiologic, histopathologic, immunohistochemical, indirect immunofluorescence, biomolecular, and serologic investigations on 8 striped dolphins (Stenella coeruleoalba) found stranded from August to December 2007 on the Ligurian Sea coast of Italy. Severe, nonsuppurative meningoencephalitis was found in 4 animals, as characterized by prominent perivascular mononuclear cell cuffing and macrophage accumulations in neuropil. These lesions were associated with mild lymphocytic-plasmacytic infiltration of choroid plexuses in 1 dolphin. Toxoplasma gondii cysts and zoites, confirmed by immunohistochemical labeling, were scattered throughout the brain parenchyma of 2 of the 4 dolphins. No viral inclusions were seen in the brain of any animal. Other findings included severe bronchointerstitial pneumonia and pulmonary atelectasis, consolidation, and emphysema. Parasites were identified in a variety of organs, including lung (Halocerchus lagenorhynchi). Microbiologic and serologic examinations for Brucella spp were negative on all 8 dolphins. The 4 animals with meningoencephalitis had serum antibodies against T gondii (titers ranging from 1:80 to 1:320) but not against morbillivirus. In contrast, the other 4 dolphins were seropositive for morbillivirus (with titers ranging from 1:10 to 1:40) but seronegative for T gondii. No morbillivirus antigen or nucleic acid was detected in the tissues of any dolphin. It is concluded that the severe lung and brain lesions were the cause of death and that T gondii was the likely etiologic agent of the cerebral lesions. Morbillivirus infection was not considered to have contributed to death of these animals.

A case of pleuropneumonia is reported in an adult male bottlenose dolphin (Tursiops truncatus) found stranded in 2014 along the Central Adriatic coast of Italy. A severe pyogranulomatous pneumonia and thoracic lymphadenopathy were present at necropsy. Numerous Splendore-Hoeppli bodies were found microscopically scattered throughout the lung. Histochemical evidence of Actinomyces-like organisms was obtained from the pulmonary parenchyma, with a strain of Photobacterium damselae subsp. piscicida and Ureaplasma spp. being also isolated from the same tissue. For the latter, a genome fragment of approximately 1400 bp from the 16s rDNA was amplified and sequenced. BLAST analysis revealed 100% identity with an uncultured Ureaplasma spp. (JQ193826.1)

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Toxoplasma gondii is a protozoan agent of increasing concern for both free-ranging and captive cetaceans. Nonetheless, information on epidemiology, biology, genetics and pathogenic potential of T. gondii for aquatic mammals is incomplete. This work provides molecular evidence for T. gondii in the brain tissue from five striped dolphins (Stenella coeruleoalba) found stranded in 2007-2008 along the Ligurian Sea coast of Italy. These animals showed a more or less severe, subacute to chronic, non purulent, multifocal meningo-encephalitis. Additionally, the cerebral parenchyma of 3 animals harboured protozoan cysts and zoites which were immunohistochemically linked to T. gondii. Consequently, a preliminary molecular investigation was undertaken to confirm the presence of the protozoan in these dolphins. Genomic DNA was extracted from the brain tissue of the animals and the extracts were examined with a nested PCR specific for the B1 gene of T. gondii. Three out of the 5 animals scored positive upon B1-PCR. Sequences were subsequently searched against the GenBankTM Database using the Basic Local Alignment Search Tool. The three sequences were identical to each other and showed 100% homology with the corresponding B1 sequence of T. gondii, with no insertions/deletions nor substitutions. The other 2 dolphins were negative upon B1-specific PCRs and also upon PCRs targeting other T. gondii genes (i.e. GRA and UPRT). To explore more in depth the genetic make-up of this protozoan, complementary studies are presently ongoing on GRA and UPRT genes of the 3 animals which were molecularly confirmed (i.e. B1-PCR) as infected by T. gondii. In conclusion, further studies are needed to elucidate a number of epidemiological and biological features of T. gondii infection in free-ranging cetaceans, with special emphasis on “pelagic” species such as striped dolphins.

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