Dataset Information

Molecular epidemiology of Brucella abortus isolates from cattle, elk, and bison in the United States, 1998 to 2011.

ABSTRACT: A variable-number tandem repeat (VNTR) protocol targeting 10 loci in the Brucella abortus genome was used to assess genetic diversity among 366 field isolates recovered from cattle, bison, and elk in the Greater Yellowstone Area (GYA) and Texas during 1998 to 2011. Minimum spanning tree (MST) and unweighted-pair group method with arithmetic mean (UPGMA) analyses of VNTR data identified 237 different VNTR types, among which 14 prominent clusters of isolates could be identified. Cattle isolates from Texas segregated into three clusters: one comprised of field isolates from 1998 to 2005, one comprised of vaccination-associated infections, and one associated with an outbreak in Starr County in January 2011. An isolate obtained from a feral sow trapped on property adjacent to the Starr County herd in May 2011 clustered with the cattle isolates, suggesting a role for feral swine as B. abortus reservoirs in Starr County. Isolates from a 2005 cattle outbreak in Wyoming displayed VNTR-10 profiles matching those of strains recovered from Wyoming and Idaho elk. Additionally, isolates associated with cattle outbreaks in Idaho in 2002, Montana in 2008 and 2011, and Wyoming in 2010 primarily clustered with isolates recovered from GYA elk. This study indicates that elk play a predominant role in the transmission of B. abortus to cattle located in the GYA.

SUBMITTER: Higgins J

PROVIDER: S-EPMC3346378 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature

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Molecular epidemiology of Brucella abortus isolates from cattle, elk, and bison in the United States, 1998 to 2011.

Higgins James J Stuber Tod T Quance Christine C Edwards William H WH Tiller Rebekah V RV Linfield Tom T Rhyan Jack J Berte Angela A Harris Beth B

Applied and environmental microbiology 20120316 10

A variable-number tandem repeat (VNTR) protocol targeting 10 loci in the Brucella abortus genome was used to assess genetic diversity among 366 field isolates recovered from cattle, bison, and elk in the Greater Yellowstone Area (GYA) and Texas during 1998 to 2011. Minimum spanning tree (MST) and unweighted-pair group method with arithmetic mean (UPGMA) analyses of VNTR data identified 237 different VNTR types, among which 14 prominent clusters of isolates could be identified. Cattle isolates fr ...[more]

PMID: 22427502

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Project description:Brucellosis is a major zoonotic infection in Kazakhstan. However, there is limited data on its incidence in humans and animals, and the genetic diversity of prevalent strains is virtually unstudied. Additionally, there is no detailed overview of Kazakhstan brucellosis control and eradication programs. Here, we analyzed brucellosis epidemiological data, and assessed the effectiveness of eradication strategies employed over the past 70 years to counteract this infection. We also conducted multiple loci variable-number tandem repeat analysis (MLVA) of Brucella abortus strains found in Kazakhstan. We analyzed official data on the incidence of animal brucellosis in Kazakhstan. The records span more than 70 years of anti-brucellosis campaigns, and contain a brief description of the applied control strategies, their effectiveness, and their impact on the incidence in humans. The MLVA-16 method was used to type 94 strains of B. abortus and serial passages of B. abortus 82, a strain used in vaccines. MLVA-8 and MLVA-11 analyses clustered strains into a total of four and seven genotypes, respectively; it is the first time that four of these genotypes have been described. MLVA-16 analysis divided strains into 28 distinct genotypes having genetic similarity coefficient that varies from 60 to100% and a Hunter & Gaston diversity index of 0.871. MST analysis reconstruction revealed clustering into "Kazakhstani-Chinese (Central Asian)", "European" and "American" lines. Detection of multiple genotypes in a single outbreak confirms that poorly controlled trade of livestock plays a crucial role in the spread of infection. Notably, the MLVA-16 profile of the B. abortus 82 strain was unique and did not change during 33 serial passages. MLVA genotyping may thus be useful for epidemiological monitoring of brucellosis, and for tracking the source(s) of infection. We suggest that countrywide application of MLVA genotyping would improve the control of brucellosis in Kazakhstan.

Project description:BackgroundAzerbaijan currently ranks thirteenth in global incidence of human brucellosis, with an estimated annual incidence through 2000 at over 50 cases per million. Brucella melitensis has been isolated from patients and is thought to have been acquired through contact with small ruminants or as a foodborne infection. To reduce the burden of human brucellosis, the Azerbaijani government began in 2002, a nationwide vaccination control campaign in small ruminants. There is serological evidence of bovine brucellosis (presumably due to Brucella abortus) in Azerbaijan, but no prevalence estimates were available when this study started in March 2017. The aim of this study was to isolate and identify Brucella spp. from cow milk in the Ganja region, where brucellosis takes a heavy toll on humans and livestock.ResultsBlood and milk samples were collected from cows (n = 1075) in early lactation (up to 90-days) in farms that had a history of previous positive serological results and abortions. Twenty-two out of 57 milk samples collected from seropositive cows, showed growth on Farrell's media, when incubated with 5% CO2. Eight additional milk samples showed growth in the absence of CO2. The classical biotyping classified them as Brucella abortus (22) and Brucella melitensis (8). RT-PCR confirmed that strains belonged to the genus Brucella. MLVA profiles were obtained for DNA extracted from two B. abortus and six B. melitensis strains. While the B. abortus genetic profile was described in the MLVA database, matching the profile of B. abortus strains isolated in East Europe, Central Asia and China, we found a new genotype for the B. melitensis strains isolated in Azerbaijan, clustering with strains belonging to the American clade, rarely identified in the region.ConclusionDespite the implementation of the vaccination program in small ruminants, our results suggest that spill-over events of B. melitensis from small ruminants to cattle have occurred. However, cattle are likely to be primarily infected with B. abortus, which warranted the implementation of a bovine brucellosis program. Such a program started in fall 2017. In the Ganja region, cattle should be considered as a potential source of B. abortus and B. melitensis for humans.

Dataset Information

Molecular epidemiology of Brucella abortus isolates from cattle, elk, and bison in the United States, 1998 to 2011.

Publications

Molecular epidemiology of Brucella abortus isolates from cattle, elk, and bison in the United States, 1998 to 2011.

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