Infection with Brucella spp., long known as a cause of abortion, infertility, and reproductive loss in domestic livestock, has increasingly been documented in marine mammals over the past two decades. We report molecular evidence of Brucella infection in Asian sea otters (Enhydra lutris lutris). Brucella DNA was detected in 3 of 78 (4%) rectal swab samples collected between 2004 and 2006 on Bering Island, Russia. These 78 animals had previously been documented to have a Brucella seroprevalence of 28%, markedly higher than the prevalence documented in sea otters (Enhydra lutris) in North America. All of the DNA sequences amplified were identical to one or more previously isolated Brucella spp. including strains from both terrestrial and marine hosts. Phylogenetic analysis of this sequence suggested that one animal was shedding Brucella spp. DNA with a sequence matching a Brucella abortus strain, whereas two animals yielded a sequence matching a group of strains including isolates classified as Brucella pinnipedialis and Brucella melitensis. Our results highlight the diversity of Brucella spp. within a single sea otter population.
Epidemiological analysis has indicated that rat and reindeer brucellosis foci are of definite value in Siberia and the Far East in the liquidation of brucellosis ones. Foci of cattle and reindeer have been first established, evidence has been provided for the epidemiological significance of fifth-biological variant B. ovis and B. suis, as well as the ecological confinement of peculiar B. rangiferi cultures to the brucellosis foci in the Arctic. To plan antibrucellosis efforts, it is necessary to take into account the incidence of human infection, as well as the insidious circulation of the bacillus in the stock farms.
Brucellosis is a highly infectious zoonotic disease but rare in Sweden. Nonetheless, an outbreak of canine brucellosis caused by an infected dog imported to Sweden was verified in 2013. In total 25 dogs were tested at least duplicated by the following approaches: real-time PCR for the detection of Brucella canis, a Brucella genus-specific real-time PCR, selective cultivation, and microscopic examination. The whole genome of B. canis strain SVA13 was analysed regarding genetic markers for epidemiological examination. The genome of an intact prophage of Roseobacter was detected in B. canis strain SVA13 with whole genome sequence prophage analysis (WGS-PA). It was shown that the prophage gene content in the American, African and European isolates differs remarkably from the Asian strains. The prophage sequences in Brucella may therefore serve of use as genetic markers in epidemiological investigations. Phage DNA fragments were also detected in clustered, regularly interspaced short palindromic repeats (CRISPR) in the genome of strain SVA13. In addition to the recommendations for genetic markers in Brucella outbreak tracing, our paper reports a validated two-step stand-alone real-time PCR for the detection of B. canis and its first successful use in an outbreak investigation.
Comparative molecular-genetic typing of Brucella strains isolated in Mongolia from different animal species as well as from humans.
Twenty-one strains of Brucella isolated from different hosts in 7 provinces of Mongolia were typed. Conventional phenotypic methods, genotyping by PCR with primers for genus- and species-specific differentiating targets of Brucella genes as well as multiple locus variable number tandem repeats analysis (MLVA) with 12 pairs of primers bounding locus variable tandem repeats of different length (from 134 bp to 8 bp).
Phenotypic identification and genotyping by PCR using primers for differentiating DNA markers allowed to attribute 14 isolates to B. melitensis biovar 2, and 7 - to B. abortus biovar 3. By using the MLVA method, connection of MLVA genotypes of 9 Brucella isolates with their reservoir hosts (sheep, cows) was shown providing their circulation in Khentii, Bulqan, and Khubsgul provinces bordering with Russia. Nine isolates from different hosts (camel, yaks, goats, sheep) isolated in Ovorkhangai, Dundgovi, and Dornogovi provinces, which have not border with Russia, had closely related MLVA genotypes indicating an opportunity of migration of pathogenic Brucella species to not-typical hosts.
Molecular-genetic typing of Brucella isolated in Mongolia was done for the first time; levels of their genetic relation and diversity were demonstrated. Circulation of Brucella isolated with specific MLVA genotypes was connected to territories of specific Mongolian provinces. The study proved migration of Brucella to not-typical hosts. Comparative study of isolates circulating in frontier with Mongolia areas of Russia (Irkutsk region, Tyva and Buryat Republics) are necessary to perform.
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.
The northern fur seal (Callorhinus ursinus) is an important cultural and nutritional resource for the Aleut community on St. Paul Island Alaska. In recent years, an increasing number of zoonotic pathogens have been identified in the population, but the public health significance of these findings is unknown. To determine the prevalence of Coxiella burnetii and Brucella spp. in northern fur seal tissues, eight tissue types from 50 subsistence-harvested fur seals were tested for bacterial DNA by real-time polymerase chain reaction.
Of the 400 samples tested, only a single splenic sample was positive for Brucella spp. and the cycle threshold (ct) value was extremely high suggesting a low concentration of DNA within the tissue. C. burnetii DNA was not detected.
Findings suggest that the risk of humans contracting brucellosis or Q fever from the consumption of harvested northern fur seals is low.
Zoonotic infections transmitted from marine mammals to humans in the Baltic and European Arctic are of unknown significance, despite given considerable potential for transmission due to local hunt. Here we present results of an initial screening for Brucella spp. in Arctic and Baltic seal species. Baltic ringed seals (Pusa hispida, n?=?12) sampled in October 2015 and Greenland Sea harp seals (Pagophilus groenlandicus, n?=?6) and hooded seals (Cystophora cristata, n?=?3) sampled in March 2015 were serologically analysed for antibodies against Brucella spp. The serological analyses were performed using the Rose Bengal Test (RBT) followed by a confirmatory testing of RBT-positive samples by a competitive-enzyme linked immunosorbent assay (C-ELISA). Two of the Baltic ringed seals (a juvenile male and a juvenile female) were seropositive thus indicating previous exposure to a Brucella spp. The findings indicate that ringed seals in the Baltic ecosystem may be exposed to and possibly infected by Brucella spp. No seropositive individuals were detected among the Greenland harp and hooded seals. Although our initial screening shows a zoonotic hazard to Baltic locals, a more in-depth epidemiological investigation is needed in order to determine the human risk associated with this.