Brucella ceti and Brucellosis in Cetaceans

Abstract

Since the first case of brucellosis detected in a dolphin aborted fetus, an increasing number of Brucella ceti isolates has been reported in members of the two suborders of cetaceans: Mysticeti and Odontoceti. Serological surveys have shown that cetacean brucellosis may be distributed worldwide in the oceans. Although all B. ceti isolates have been included within the same species, three different groups have been recognized according to their preferred host, bacteriological properties, and distinct genetic traits: B. ceti dolphin type, B. ceti porpoise type, and B. ceti human type. It seems that B. ceti porpoise type is more closely related to B. ceti human isolates and B. pinnipedialis group, while B. ceti dolphin type seems ancestral to them. Based on comparative phylogenetic analysis, it is feasible that the B. ceti ancestor radiated in a terrestrial artiodactyl host close to the Raoellidae family about 58 million years ago. The more likely mode of transmission of B. ceti seems to be through sexual intercourse, maternal feeding, aborted fetuses, placental tissues, vertical transmission from mother to the fetus or through fish or helminth reservoirs. The B. ceti dolphin and porpoise types seem to display variable virulence in land animal models and low infectivity for humans. However, brucellosis in some dolphins and porpoises has been demonstrated to be a severe chronic disease, displaying significant clinical and pathological signs related to abortions, male infertility, neurobrucellosis, cardiopathies, bone and skin lesions, strandings, and death.

Meningoencephalitis and Arthritis Associated with Brucella ceti in a Short-beaked Common Dolphin (Delphinus delphis)

“…(Gonzá lez et al, 2002;Jepson, 2006;Muň oz et al, 2006;Dagleish et al, 2007;Herná ndez-Mora et al, 2008;Davison et al, 2009;Guzmá n-Verri et al, 2012). To our knowledge, this is the first confirmed report of B. ceti-associated CNS and musculoskeletal pathology in a shortbeaked common dolphin.…”

Exposure of harbour seals Phoca vitulina to Brucella in declining populations across Scotland

“…However, there has been no evidence in pinnipeds of disease due to B. pinnipedialis as has been seen with B. ceti infection in dolphins and porpoises where chronic disease with significant clinical and pathological signs including male infertility, neurobrucellosis, cardiopathies, bone and skin lesions and live strandings have been documented (Guzmán-Verri et al 2012). While no evidence of disease has been reported in pinnipeds, detecting abortions in wild populations is very difficult, especially if the occurrence remains constant over time and there is limited data on pupping success, as is the case for the populations sampled here.…”

“…It is likely that the routes of transmission are similar to those of terrestrial mammals, whereby transmission occurs through exposure to infected placenta, birth fluids and vaginal secretions as well as by venereal spread (Young 2006). As Brucella has been isolated from the reproductive organs of several cetacean species (Miller et al 1999, González-Barrientos et al 2010, and from an aborted foetus of a captive bottlenose dolphin (Ewalt et al 1994), the most likely mode of transmission of B. ceti appears to be through sexual intercourse, vertical transmission from mother to foetus, maternal feeding and contact with aborted foetuses and placental tissues (Guzmán-Verri et al 2012). The transmission between pinnipeds is even less well understood, but it could be similar to cetaceans.…”

Brucellosis in marine mammals, with special emphasis on the Republic of Croatia

“…In the western Atlantic, Brucella strains have been isolated in mammals off the coasts of New England and the entire eastern seaboard of the United States, and in the Gulf of Mexico. Brucella strains have also been isolated in the eastern and southwestern Pacific [22][23][24]. Brucella infections in marine mammals are globally distributed [25].…”

“…It is believed that the strains isolated from the dolphins and porpoises are variable in experiments on terrestrial animals, and are not infectious for humans. However, brucellosis has proven to be a highly chronic disease in certain common dolphins and harbour porpoises, with severe clinical signs and pathological signs relating to abortions, male infertility, neurobrucellosis, cardiopathology, bone lesions and skin, beachings and ultimately in death [22].…”