Brucella ceti Infection in Striped Dolphins from Italian Seas: Associated Lesions and Epidemiological Data

Abstract

Brucella ceti infections have been increasingly reported in cetaceans. In this study, we analyzed all cases of B. ceti infection detected in striped dolphins stranded along the Italian coastline between 2012 and 2021 (N = 24). We focused on the pathogenic role of B. ceti through detailed pathological studies, and ad hoc microbiological, biomolecular, and serological investigations, coupled with a comparative genomic analysis of the strains. Neurobrucellosis was observed in 20 animals. The primary histopathologic features included non-suppurative meningoencephalitis (N = 9), meningitis (N = 6), and meningoencephalomyelitis (N = 5), which was also associated with typical lesions in other tissues (N = 8). Co-infections were detected in more than half of the cases, mostly involving Cetacean Morbillivirus (CeMV). The 24 B. ceti isolates were assigned primarily to sequence type 26 (ST26) (N = 21) and, in a few cases, ST49 (N = 3). The multilocus sequence typing (cgMLST) based on whole genome sequencing (WGS) data showed that strains from Italy clustered into four genetically distinct clades. Plotting these clades onto a geographic map suggests a link between their phylogeny and the topographical distribution. These results support the role of B. ceti as a primary neurotropic pathogen for striped dolphins and highlight the utility of WGS data in understanding the evolution of this emerging pathogen.

The First Report of Pennella (Crustacea: Copepoda) Infesting Stenella coeruleoalba Stranded in Malta: Morphological and Genetic Analyses

“…Just as parasites, including Pennella balaenoptera, may benefit from a weakened host, the parasites themselves may be carriers of infectious pathogens, such as Brucella ceti, which, in turn, may have long debilitating effects on the dolphin, potentially facilitating further parasite infestation. At the same time, other diseases, such as Cetacean morbillivirus (CeMV), may also coinfect or activate various other latent infections, weakening the dolphin in various life-threatening ways [32,34,[46][47][48][49][50].…”

“…In the Mediterranean, CeMV and Brucella ceti are known to be responsible for infectious outbreaks and deaths in striped dolphins [40,46,47,[51][52][53][54]. Infected individuals are or may become immunosuppressed and exhibit significant depletion of lymphoid tissue [39].…”

Whales and dolphins of the Adriatic Sea

“…For instance, one individual stranded in Apulia in November 2016 was diagnosed with suppurative encephalitis associated to dolphin morbillivirus (Giorda et al, 2022). One individual stranded in Molise in February 2019, and one stranded in Apulia in December 2020, showed a co-infection of dolphin morbillivirus and Brucella ceti (Grattarola et al, 2023). Three sperm whales from a group of seven that mass-stranded alive in September 2014 near Vasto (see the Sperm whale section) were infected by dolphin morbillivirus, and this was thought to have played a role in weakening the animals and affecting their orientation (Mazzariol et al, 2018a).…”

“…For instance, an adult male bottlenose dolphin stranded in the region of Abruzzo in 2014 had a bilateral pleuropneumonia and bacterial coinfections by Ureaplasma spp., Photobacterium damselae and Actinomyces-like species (Di Francesco et al, 2016). Seven of nine striped dolphins stranded in Abruzzo, Molise and Apulia between 2013-2021 had infections by the bacterial pathogen Brucella ceti (Grattarola et al, 2023). Pathogens including Vibro parahaemolyticus and V. alginolyticus were detected in a bottlenose dolphin stranded in Abruzzo in July 2016, and linked to a suppurative meningoencephalitis (Di Renzo et al, 2017).…”