Seroconversion and abortion in cattle experimentally infected with Brucella sp. isolated from a Pacific harbor seal (Phoca vitulina richardsi)

[Zoonotic potential of brucellosis in marine mammals]

Introduction

Brucellosis in marine mammals (cetacean and pinnipeds) has emerged in a very significant way during the last two decades. Currently Brucella ceti and Brucella pinnipedialis are the two recognized species in marine mammals, but available information is still limited. Several genotypes have been identified, and studies on the relationship between sequence type (ST) and organ pathogenicity or tropism have indicated differences in pathogenesis between B. ceti sequences in cetaceans. The zoonotic potential of this disease is based on the identification of the main sources of introduction and spread of Brucella spp. in the marine environment as well as on the factors of exposure of marine mammals and humans to the bacteria.

Bibliographic review

This article is a bibliographical review on marine mammal brucellosis, including the features, sources and transmission modes of each Brucella species, as well as their potential pathogenicity in animals and humans.

Conclusion

Different genotypes of marine Brucella spp have been isolated from marine mammal species but without any evidence of pathology induced by these bacteria. Associated lesions are variable and include subcutaneous abscesses, meningo-encephalomyelitis, pneumonia, myocarditis, osteoarthritis, orchitis, endometritis, placentitis and abortion. The isolation of marine B. spp from marine mammal respiratory parasites associated to lung injury has raised the intriguing possibility that they may serve as a vector for the transmission of this bacterium.The severity of marine B. spp remains unknown due to the lack of an estimate of the prevalence of this disease in marine mammals. The number of suspected human cases is still very limited. However, by analogy with other germs of the genus Brucella responsible for abortion in ruminants and for a febrile and painful state in human beings, prevention measures are essential. The significant increase in the number of strandings coupled with a high seroprevalence in certain species of marine mammals must be considered for people in direct or indirect contact with these animals. Ongoing epidemiological monitoring combined with extensive post-mortem examinations (necropsy, bacteriology and sequencing) of all species of stranded marine mammals would deepen knowledge on the zoonotic potential of marine Brucella species.

Occurrence of Brucella ceti in striped dolphins from Italian Seas

Brucella ceti infections have been increasingly reported in cetaceans, although a very limited characterization of Mediterranean Brucella spp. isolates has been previously reported and relatively few data exist about brucellosis among cetaceans in Italy. To address this gap, we studied 8 cases of B. ceti infection in striped dolphins (Stenella coeruleoalba) stranded along the Italian coastline from 2012 to 2018, investigated thanks to the Italian surveillance activity on stranded cetaceans. We focused on cases of stranding in eastern and western Italian seas, occurred along the Apulia (N = 6), Liguria (N = 1) and Calabria (N = 1) coastlines, through the analysis of gross and microscopic findings, the results of microbiological, biomolecular and serological investigations, as well as the detection of other relevant pathogens. The comparative genomic analysis used whole genome sequences of B. ceti from Italy paired with the publicly available complete genomes. Pathological changes consistent with B. ceti infection were detected in the central nervous system of 7 animals, showing non-suppurative meningoencephalitis. In 4 cases severe coinfections were detected, mostly involving Dolphin Morbillivirus (DMV). The severity of B. ceti-associated lesions supports the role of this microbial agent as a primary neurotropic pathogen for striped dolphins. We classified the 8 isolates into the common sequence type 26 (ST-26). Whole genome SNP analysis showed that the strains from Italy clustered into two genetically distinct clades. The first clade comprised exclusively the isolates from Ionian and Adriatic Seas, while the second one included the strain from the Ligurian Sea and those from the Catalonian coast. Plotting these clades onto the geographic map suggests a link between their phylogeny and topographical distribution. These results represent the first extensive characterization of B. ceti isolated from Italian waters reported to date and show the usefulness of WGS for understanding of the evolution of this emerging pathogen.

Molecular, serological, pathological, immunohistochemical and microbiological investigation of Brucella spp. in marine mammals of Brazil reveals new cetacean hosts

Brucella-exposure and infection is increasingly recognized in marine mammals worldwide. To better understand the epidemiology and health impacts of Brucella spp. in marine mammals of Brazil, molecular (conventional PCR and/or real-time PCR), serological (Rose Bengal Test [RBT], Competitive [c]ELISA, Serum Agglutination Test [SAT]), pathological, immunohistochemical (IHC) and/or microbiological investigations were conducted in samples of 129 stranded or by-caught marine mammals (orders Cetartiodactyla [n = 124], Carnivora [n = 4] and Sirenia [n = 1]). Previous serological tests performed on available sera of 27 of the 129 animals (26 cetaceans and one manatee), indicated 10 seropositive cetaceans. Conventional PCR and/or real-time PCR performed in cases with available organs (n = 119) and/or blood or swabs (n = 10) revealed 4/129 (3.1%) Brucella-infected cetaceans (one of them with positive serology; the remaining three with no available sera). Pathological, IHC and/or microbiological analyses conducted in PCR/real-time PCR and/or seropositive cases (n = 13) revealed Brucella-type lesions, including meningitis/meningoencephalitis, pneumonia, necrotizing hepatitis, pericarditis and osteoarthritis in some of those animals, and positive IHC was found in all of them (excepting two live-stranded animals without available organs). Brucella spp. culture attempts were unsuccessful. Our results demonstrated exposure, asymptomatic, acute and chronic Brucella sp. infection in several cetacean species in the Brazilian coast, highlighting the role of this pathogen in stranding and/or death, particularly in Clymene dolphin (Stenella clymene) and short-finned pilot whale (Globicephala macrorhynchus) off Ceará State. Novel hosts susceptible to Brucella included the franciscana (Pontoporia blainvillei), the Guiana dolphin (Sotalia guianensis) and the spinner dolphin (Stenella longirostris). Additionally, three coinfection cases involving Brucella spp. and cetacean morbillivirus, Edwarsiella tarda and Proteus mirabilis were detected. To the best of our knowledge, this is the first long-term and large-scale survey of Brucella spp. in marine mammals of South America, widening the spectrum of susceptible hosts and geographical distribution range of this agent with zoonotic potential.

Brucella pinnipedialis in lungworms Parafilaroides sp. and Pacific harbor seals Phoca vitulina richardsi: proposed pathogenesis

Brucella spp. were first isolated from marine mammals in 1994 and since have been described in numerous pinniped and cetacean species with nearly global distribution. Microscopic, electron microscopic, or culture results have shown lungworms in harbor seals to be infected with brucellae, suggesting that the lungworms may serve a role in this infection. In this study, we reviewed archived and more recent case material from 5 Pacific harbor seals from Washington State (USA) with evidence of B. pinnipedialis infection in the lungworm Parafilaroides sp. Twenty-two sections of lung containing approximately 220 Parafilaroides sp., stained with an immunohistochemical technique using antibody to B. abortus, showed approximately 80 (36%) infected nematodes. A few brucellae were also present in lung parenchyma in proximity to nematodes. Infection was present in the first- and fourth-stage larvae in the seal lung and intestines, as well as in the male and female reproductive organs of adult nematodes. Infected sperm deposits in the nematode uterus were suggestive of venereal transmission between lungworms. Massive infection of some degenerate adult lungworms and evidence of degeneration of some developing larvae in utero were observed. Based on these observations, we suggest that Parafilaroides sp., rather than the Pacific harbor seal Phoca vitulina richardsi, is the preferred host of B. pinnipedialis infection.

Brucella placentitis and seroprevalence in northern fur seals ( Callorhinus ursinus) of the Pribilof Islands, Alaska

Brucella species infect a wide range of hosts with a broad spectrum of clinical manifestations. In mammals, one of the most significant consequences of Brucella infection is reproductive failure. There is evidence of Brucella exposure in many species of marine mammals, but the outcome of infection is often challenging to determine. The eastern Pacific stock of northern fur seals (NFSs, Callorhinus ursinus) has declined significantly, spawning research into potential causes for this trend, including investigation into reproductive health. The objective of the current study was to determine if NFSs on St. Paul Island, Alaska have evidence of Brucella exposure or infection. Archived DNA extracted from placentas ( n = 119) and serum ( n = 40) samples were available for testing by insertion sequence (IS) 711 polymerase chain reaction (PCR) and the Brucella microagglutination test (BMAT), respectively. As well, placental tissue was available for histologic examination. Six (5%) placentas were positive by PCR, and a single animal had severe placentitis. Multilocus variable number tandem repeat analysis profiles were highly clustered and closely related to other Brucella pinnipedialis isolates. A single animal was positive on BMAT, and 12 animals had titers within the borderline range; 1 borderline animal was positive by PCR on serum. The findings suggest that NFSs on the Pribilof Islands are exposed to Brucella and that the organism has the ability to cause severe placental disease. Given the population trend of the NFS, and the zoonotic nature of this pathogen, further investigation into the epidemiology of this disease is recommended.

Seroprevalence of Brucella antibodies in harbor seals in Alaska, USA, with age, regional, and reproductive comparisons

Populations of harbor seal Phoca vitulina in the Gulf of Alaska have dramatically declined during the past 4 decades. Numbers of seals in Glacier Bay, in southeast Alaska, USA, have also declined despite extensive protection. Causes of the declines and slow recovery are poorly understood. Brucellosis is a zoonotic disease that adversely affects reproduction in many domestic species. We measured the seroprevalence of Brucella antibodies in 554 harbor seals in 3 Alaska locations: Prince William Sound (PWS), Glacier Bay (GB), and Tracy Arm Fords Terror (TAFT) Wilderness Area. Objectives included testing for regional, sex, age, and female reproductive state differences in Brucella antibody seroprevalence, persistence in titers in recaptured seals, and differences in titers between mother seals and their pups. Overall, 52% of adults (AD), 53% of subadults (SA), 77% of yearlings (YRL), and 26% of <5 mo old pups were seropositive. Matched mother-pup samples were consistent with dependent pups acquiring maternal passive immunity to Brucella. Results show higher seroprevalence (64%) for AD and SA seals in the depressed and declining populations in PWS and GB than in TAFT (29%). Lactating females were less likely to be seropositive than other AD females, including pregnant females. Further research is needed to seek evidence of Brucella infection in Alaskan harbor seals, identify effects on neonatal viability, and assess zoonotic implications for Alaska Natives who rely on harbor seals for food.

ISOLATION AND CHARACTERIZATION OF A NOVEL MARINE BRUCELLA FROM A SOUTHERN SEA OTTER (ENHYDRA LUTRIS NEREIS), CALIFORNIA, USA

We characterize Brucella infection in a wild southern sea otter ( Enhydra lutris nereis) with osteolytic lesions similar to those reported in other marine mammals and humans. This otter stranded twice along the central California coast, US over a 1-yr period and was handled extensively at two wildlife rehabilitation facilities, undergoing multiple surgeries and months of postsurgical care. Ultimately the otter was euthanized due to severe, progressive neurologic disease. Necropsy and postmortem radiographs revealed chronic, severe osteoarthritis spanning the proximal interphalangeal joint of the left hind fifth digit. Numerous coccobacilli within the joint were strongly positive on Brucella immunohistochemical labelling, and Brucella sp. was isolated in pure culture from this lesion. Sparse Brucella-immunopositive bacteria were also observed in the cytoplasm of a pulmonary vascular monocyte, and multifocal granulomas were observed in the spinal cord and liver on histopathology. Findings from biochemical characterization, 16S ribosomal DNA, and bp26 gene sequencing of the bacterial isolate were identical to those from marine-origin brucellae isolated from cetaceans and phocids. Although omp2a gene sequencing revealed 100% homology with marine Brucella spp. infecting pinnipeds, whales, and humans, omp2b gene sequences were identical only to pinniped-origin isolates. Multilocus sequence typing classified the sea otter isolate as ST26, a sequence type previously associated only with cetaceans. Our data suggest that the sea otter Brucella strain represents a novel marine lineage that is distinct from both Brucella pinnipedialis and Brucella ceti. Prior reports document the zoonotic potential of the marine brucellae. Isolation of Brucella sp. from a stranded sea otter highlights the importance of wearing personal protective equipment when handling sea otters and other marine mammals as part of wildlife conservation and rehabilitation efforts.

Experimental Challenge of Atlantic Cod (Gadus morhua) with a Brucella pinnipedialis Strain from Hooded Seal (Cystophora cristata)

Pathology has not been observed in true seals infected with Brucella pinnipedialis. A lack of intracellular survival and multiplication of B. pinnipedialis in hooded seal (Cystophora cristata) macrophages in vitro indicates a lack of chronic infection in hooded seals. Both epidemiology and bacteriological patterns in the hooded seal point to a transient infection of environmental origin, possibly through the food chain. To analyse the potential role of fish in the transmission of B. pinnipedialis, Atlantic cod (Gadus morhua) were injected intraperitoneally with 7.5 x 10⁷ bacteria of a hooded seal field isolate. Samples of blood, liver, spleen, muscle, heart, head kidney, female gonads and feces were collected on days 1, 7, 14 and 28 post infection to assess the bacterial load, and to determine the expression of immune genes and the specific antibody response. Challenged fish showed an extended period of bacteremia through day 14 and viable bacteria were observed in all organs sampled, except muscle, until day 28. Neither gross lesions nor mortality were recorded. Anti-Brucella antibodies were detected from day 14 onwards and the expression of hepcidin, cathelicidin, interleukin (IL)-1β, IL-10, and interferon (IFN)-γ genes were significantly increased in spleen at day 1 and 28. Primary mononuclear cells isolated from head kidneys of Atlantic cod were exposed to B. pinnipedialis reference (NCTC 12890) and hooded seal (17a-1) strain. Both bacterial strains invaded mononuclear cells and survived intracellularly without any major reduction in bacterial counts for at least 48 hours. Our study shows that the B. pinnipedialis strain isolated from hooded seal survives in Atlantic cod, and suggests that Atlantic cod could play a role in the transmission of B. pinnipedialis to hooded seals in the wild.

Marine Mammal Brucella Reference Strains Are Attenuated in a BALB/c Mouse Model

Brucellosis is a zoonosis of worldwide distribution with numerous animal host species. Since the novel isolation of Brucella spp. from marine mammals in 1994 the bacteria have been isolated from various marine mammal hosts. The marine mammal reference strains Brucella pinnipedialis 12890 (harbour seal, Phoca vitulina) and Brucella ceti 12891 (harbour porpoise, Phocoena phocoena) were included in genus Brucella in 2007, however, their pathogenicity in the mouse model is pending. Herein this is evaluated in BALB/c mice with Brucella suis 1330 as a control. Both marine mammal strains were attenuated, however, B. ceti was present at higher levels than B. pinnipedialis in blood, spleen and liver throughout the infection, in addition B. suis and B. ceti were isolated from brains and faeces at times with high levels of bacteraemia. In B. suis-infected mice serum cytokines peaked at day 7. In B. pinnipedialis-infected mice, levels were similar, but peaked predominantly at day 3 and an earlier peak in spleen weight likewise implied an earlier response. The inflammatory response induced pathology in the spleen and liver. In B. ceti-infected mice, most serum cytokine levels were comparable to those in uninfected mice, consistent with a limited inflammatory response, which also was indicated by restricted spleen and liver pathology. Specific immune responses against all three strains were detected in vitro after stimulation of splenocytes from infected mice with the homologous heat-killed brucellae. Antibody responses in vivo were also induced by the three brucellae. The immunological pattern of B. ceti in combination with persistence in organs and limited pathology has heretofore not been described for other brucellae. These two marine mammal wildtype strains show an attenuated pattern in BALB/c mice only previously described for Brucella neotomea.

Retrospective and prospective perspectives on zoonotic brucellosis

Members of the genus Brucella are pathogenic bacteria exceedingly well adapted to their hosts. The bacterium is transmitted by direct contact within the same host species or accidentally to secondary hosts, such as humans. Human brucellosis is strongly linked to the management of domesticated animals and ingestion of their products. Since the domestication of ungulates and dogs in the Fertile Crescent and Asia in 12000 and 33000 ya, respectively, a steady supply of well adapted emergent Brucella pathogens causing zoonotic disease has been provided. Likewise, anthropogenic modification of wild life may have also impacted host susceptibility and Brucella selection. Domestication and human influence on wild life animals are not neutral phenomena. Consequently, Brucella organisms have followed their hosts’ fate and have been selected under conditions that favor high transmission rate. The “arm race” between Brucella and their preferred hosts has been driven by genetic adaptation of the bacterium confronted with the evolving immune defenses of the host. Management conditions, such as clustering, selection, culling, and vaccination of Brucella preferred hosts have profound influences in the outcome of brucellosis and in the selection of Brucella organisms. Countries that have controlled brucellosis systematically used reliable smooth live vaccines, consistent immunization protocols, adequate diagnostic tests, broad vaccination coverage and sustained removal of the infected animals. To ignore and misuse tools and strategies already available for the control of brucellosis may promote the emergence of new Brucella variants. The unrestricted use of low-efficacy vaccines may promote a “false sense of security” and works towards selection of Brucella with higher virulence and transmission potential.

Entrance and survival of Brucella pinnipedialis hooded seal strain in human macrophages and epithelial cells

Marine mammal Brucella spp. have been isolated from pinnipeds (B. pinnipedialis) and cetaceans (B. ceti) from around the world. Although the zoonotic potential of marine mammal brucellae is largely unknown, reports of human disease exist. There are few studies of the mechanisms of bacterial intracellular invasion and multiplication involving the marine mammal Brucella spp. We examined the infective capacity of two genetically different B. pinnipedialis strains (reference strain; NTCT 12890 and a hooded seal isolate; B17) by measuring the ability of the bacteria to enter and replicate in cultured phagocytes and epithelial cells. Human macrophage-like cells (THP-1), two murine macrophage cell lines (RAW264.7 and J774A.1), and a human malignant epithelial cell line (HeLa S3) were challenged with bacteria in a gentamicin protection assay. Our results show that B. pinnipedialis is internalized, but is then gradually eliminated during the next 72 – 96 hours. Confocal microscopy revealed that intracellular B. pinnipedialis hooded seal strain colocalized with lysosomal compartments at 1.5 and 24 hours after infection. Intracellular presence of B. pinnipedialis hooded seal strain was verified by transmission electron microscopy. By using a cholesterol-scavenging lipid inhibitor, entrance of B. pinnipedialis hooded seal strain in human macrophages was significantly reduced by 65.8 % (± 17.3), suggesting involvement of lipid-rafts in intracellular entry. Murine macrophages invaded by B. pinnipedialis do not release nitric oxide (NO) and intracellular bacterial presence does not induce cell death. In summary, B. pinnipedialis hooded seal strain can enter human and murine macrophages, as well as human epithelial cells. Intracellular entry of B. pinnipedialis hooded seal strain involves, but seems not to be limited to, lipid-rafts in human macrophages. Brucella pinnipedialis does not multiply or survive for prolonged periods intracellulary.

Brucella ceti and brucellosis in cetaceans

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.

A review of Brucella infection in marine mammals, with special emphasis on Brucella pinnipedialis in the hooded seal (Cystophora cristata)

Brucella spp. were isolated from marine mammals for the first time in 1994. Two novel species were later included in the genus; Brucella ceti and Brucella pinnipedialis, with cetaceans and seals as their preferred hosts, respectively. Brucella spp. have since been isolated from a variety of marine mammals. Pathological changes, including lesions of the reproductive organs and associated abortions, have only been registered in cetaceans. The zoonotic potential differs among the marine mammal Brucella strains. Many techniques, both classical typing and molecular microbiology, have been utilised for characterisation of the marine mammal Brucella spp. and the change from the band-based approaches to the sequence-based approaches has greatly increased our knowledge about these strains. Several clusters have been identified within the B. ceti and B. pinnipedialis species, and multiple studies have shown that the hooded seal isolates differ from other pinniped isolates. We describe how different molecular methods have contributed to species identification and differentiation of B. ceti and B. pinnipedialis, with special emphasis on the hooded seal isolates. We further discuss the potential role of B. pinnipedialis for the declining Northwest Atlantic hooded seal population.

Bovine brucellosis

Infection of cattle caused by Brucella abortus (ie, bovine brucellosis) has been of political importance in the United States for many decades. The most common clinical manifestation of brucellosis in natural hosts is reproductive loss resulting from abortion, birth of weak offspring, or infertility. Brucellosis regulatory programs were primarily developed as the most efficient way to prevent human infections. This article discusses cattle vaccination with B abortus strains 19 and RB51. Other reservoir hosts for this organism and other Brucella spp in cattle have also been visited.

Infection trials in pigs with a human isolate of Brucella ( isolate 02/611 'marine mammal type' )

AIM

To determine if pigs could support infection of a human Brucella isolate (Brucella 02/611) from New Zealand, and to study seroconversion to this isolate using a competitive ELISA.

METHODS

Ten weaner piglets were challenged with 4.8 x 10(8) cfu of organisms by the oral and ocular routes. Culture was attempted on blood samples taken prior to challenge, and 4, 7, 9, 11, 14, 21 and 28 days post-challenge, and on tissue samples taken at the termination of the trial, 1 month after challenge. Sera were analysed for antibody using an ELISA. For reference comparison, similar trials were conducted in two pigs using an isolate of Brucella suis biovar 1, and two pigs using an isolate of B. suis biovar 3.

RESULTS

Brucella 02/611 organisms were re-isolated from one lymph node each from three pigs; all other samples were negative. Low and transient antibody titres were detected using a competitive ELISA in three pigs, two of which were culture negative. Organisms of B. suis reference strains were re-isolated from multiple samples from each of the four animals.

CONCLUSION

Brucella 02/611 does not seem to replicate readily in pigs. It is unlikely that pigs were the original maintenance hosts for Brucella 02/611.

Characterization of a Brucella sp. strain as a marine-mammal type despite isolation from a patient with spinal osteomyelitis in New Zealand

Naturally acquired infection of humans with a marine mammal-associated Brucella sp. has only been reported once previously in a study describing infections of two patients from Peru. We report the isolation and characterization of a strain of Brucella from a New Zealand patient that appears most closely related to strains previously identified from marine mammals. The isolate was preliminarily identified as Brucella suis using conventional bacteriological tests in our laboratory. However, the results profile was not an exact match, and the isolate was forwarded to four international reference laboratories for further identification. The reference laboratories identified the isolate as either B. suis or B. melitensis by traditional bacteriological methods in three laboratories and by a molecular test in the fourth laboratory. Molecular characterization by PCR, PCR-restriction fragment length polymorphism, and DNA sequencing of the bp26 gene; IS711; the omp genes omp25, omp31, omp2a, and omp2b; IRS-PCR fragments I, III, and IV; and five housekeeping gene fragments was conducted to resolve the discrepant identification of the isolate. The isolate was identified to be closely related to a Brucella sp. originating from a United States bottlenose dolphin (Tursiops truncatus) and common seals (Phoca vitulina).

Prevalence of Brucella pinnipediae in healthy hooded seals (Cystophora cristata) from the North Atlantic Ocean and ringed seals (Phoca hispida) from Svalbard

Investigations for Brucella-infections were conducted in 29 hooded seals (Cystophora cristata) caught between Svalbard and Greenland (North Atlantic Ocean; Greenland Sea) autumn 2002, and from 20 ringed seals (Phoca hispida) caught in Billefjord, Svalbard, spring 2003. All animals were apparently healthy and were caught in their natural habitat. Bacteriology on tissue samples from ringed seals was negative, whereas Brucella sp. were recovered in tissues from 11 of the 29 hooded seals (38%), with the highest tissue prevalence in spleen (9/29) and lung lymph nodes (9/24). Anti-Brucella antibodies were detected in sera from 9 hooded seals (31%) (EDTA-modified Slow Agglutination test of Wright, Rose Bengal test, Complement Fixation Test, and Protein-A ELISA). The bacterial isolates all belonged to the genus Brucella according to classical biotyping and PCR analysis based on Insertion Sequence IS711, and were shown to be typical marine mammal strains, based on the occurrence of an IS711 element downstream of the bp26 gene. Their dependency on CO2 for growth, and the presence of one copy each of the omp2a and omp2b gene finally classified them as Brucella pinnipediae. Furthermore, all the hooded seal isolates showed an A+ M+ agglutination profile, which is different from the profile of reference seal strain 2/94 (harbour seal, Phoca vitulina). Thus, these results indicate that B. pinnipediae may contain different biovars. The present results suggest that infection with B. pinnipediae is enzootic in this population. Since the hooded seal is commercially hunted and consumed in Norway, the pathological impact of such infections and their zoonotic potential should be further addressed.

Human neurobrucellosis with intracerebral granuloma caused by a marine mammal Brucella spp

We present the first report of community-acquired human infections with marine mammal-associated Brucella spp. and describe the identification of these strains in two patients with neurobrucellosis and intracerebral granulomas. The identification of these isolates as marine mammal strains was based on omp2a sequence and amplification of the region flanking bp26.

Pathological and serological evidence of Brucella-infection in baleen whales (Mysticeti) in the western North Pacific

Abnormal testes and uterus were observed in 13 males (33%) and one female (3%) out of 40 common minke whales (Balaenoptera acutorostrata) in the western North Pacific. Similar lesions were found in testis and ovary, respectively, in one male (2%) and female (2%) out of 43 Bryde's whales (Balaenoptera edeni) in the western North Pacific. Grossly, granular lesions with caseation and calcification were main pathological signs, and they were restricted to reproductive organs of mature whales. Chronic purulent or granulomatous orchitis was observed by microscopic analysis. Antibodies to Brucella species were detected in the serum samples of 15/40 (38%) of common minke whales and 4/43 (9%) of Bryde's whales. Neither pathological nor serological change was found in the examined sperm whales (Physeter macrocephalus) in the western North Pacific and Antarctic minke whales (Balaenoptera bonaerensis). These results strongly suggest that Brucella infection was involved in two species of baleen whales (Mysticeti) in the North Pacific.

A review of Brucella sp. infection of sea mammals with particular emphasis on isolates from Scotland

Brucellae recovered from sea mammals were first reported in 1994. In the years since both culture and serological analysis have demonstrated that the infection occurs in a wide range of species of marine mammals inhabiting a vast amount of the world's oceans. Molecular studies have demonstrated that the isolates differ from those found amongst terrestrial animals and also distinguish between strains which have seals and cetaceans as their preferred hosts. At the phenotypic level seal and cetacean strains can also be differed with respect to their CO(2) requirement, primary growth on Farrells medium and metabolic activity on galactose. Two new species B. cetaceae and B. pinnipediae have been proposed as a result. This paper provides a review of Brucella in sea mammals and updates findings from the study of sea mammals from around the coast of Scotland.