title: First isolation, identification, phenotypic and genotypic characterization of Brucella abortus biovar 3 from dairy cattle in Tanzania.
abstract: BACKGROUND
  Brucellosis is a disease of worldwide public health and economic importance. Successful control is based on knowledge of epidemiology and strains present in an area. In developing countries, most investigations are based on serological assays. This study aimed at investigating a dairy herd experiencing abortions in order to establish within-herd seroprevalence to Brucella spp., identify, characterize Brucella strains by Multiple Loci Variable Number of Tandem Repeats Analysis (MLVA-VNTR) and investigate possible spillover to other species.
  
  
  RESULTS
  The within-herd seroprevalence in cattle (n = 200) was 48 % (95 % CI 41-55), using an indirect ELISA, while the Rose Bengal Test (RBT) yielded lower prevalence (21.5 %; 95 % CI 16-27). Two sheep (n = 35) and one goat (n = 50) were seropositive using ELISA while none of the dogs (n = 6) was positive with the RBT. Three Brucella were isolated from an aborted fetus and associated membranes. Real time PCR (IS711), Bruce-ladder and classical biotyping classified the isolates as B. abortus biovar 3. MLVA-VNTR revealed two different but closely related genotypes. The isolates showed unique profiles, providing the first genotypic data from Tanzania. These genotypes were not related to B. abortus biovar 3 reference strain Tulya originally isolated from a human patient in Uganda in 1958, unlike the genotypes isolated and characterized recently in Kenya. High within-herd prevalence, isolation of the pathogen and abortion confirm that B. abortus is circulating in this herd with cattle as reservoir hosts. A low seroprevalence in sheep and goats suggests a spillover of B. abortus from cattle to small ruminants in the herd.
  
  
  CONCLUSIONS
  This is the first isolation and characterization of B. abortus biovar 3 from a dairy cow with abortion in Tanzania. The origin of the Tanzanian genotypes remain elusive, although they seem to be related to genotypes found in Europe, Turkey and China but not related to B. abortus biovar 3 reference strain or genotypes from Kenya. Importantly, replacement heifers are commonly sourced from large farms like this to smallholder farmers, which poses risk of spread of bacteria to other herds. B. abortus is a significant zoonotic risk and animal health problem in this production system, therefore further studies on humans is recommended.
authors.affiliation: Department of Production Animals Clinical Sciences, Norwegian University of Life Science, Oslo, Norway. coletha.mathew.mtenga@nmbu.no.|Sokoine University of Agriculture, Morogoro, Tanzania. coletha.mathew.mtenga@nmbu.no.
authors.forename: C
authors.initials: C
authors.lastname: Mathew
authors.affiliation: Department of Production Animals Clinical Sciences, Norwegian University of Life Science, Oslo, Norway. maria.stokstad@nmbu.no.
authors.forename: M
authors.initials: M
authors.lastname: Stokstad
authors.affiliation: National Veterinary Institute, Oslo, Norway. tone.johansen@vetinst.no.
authors.forename: T B
authors.initials: TB
authors.lastname: Johansen
authors.affiliation: National Veterinary Institute, Oslo, Norway. siv.klevar@vetinst.no.
authors.forename: S
authors.initials: S
authors.lastname: Klevar
authors.affiliation: Sokoine University of Agriculture, Morogoro, Tanzania. mdegela@suanet.ac.tz.
authors.forename: R H
authors.initials: RH
authors.lastname: Mdegela
authors.affiliation: Sokoine University of Agriculture, Morogoro, Tanzania. glmwamengele@suanet.ac.tz.
authors.forename: G
authors.initials: G
authors.lastname: Mwamengele
authors.affiliation: Veterinary and Agrochemical Research Center, Brussels, Belgium. Patrick.Michel@coda-cerva.be.
authors.forename: P
authors.initials: P
authors.lastname: Michel
authors.affiliation: Veterinary and Agrochemical Research Center, Brussels, Belgium. Luisa.Escobar@coda-cerva.be.
authors.forename: L
authors.initials: L
authors.lastname: Escobar
authors.affiliation: Veterinary and Agrochemical Research Center, Brussels, Belgium. David.Fretin@coda-cerva.be.
authors.forename: D
authors.initials: D
authors.lastname: Fretin
authors.affiliation: Department of Arctic and Marine Biology, University of Tromsø - the Arctic University of Norway, Faculty of Biosciences, Fisheries and Economics, Research Group of Arctic Infection Biology, Langnes, Postbox 6050, 9037, Tromsø, Norway. Jacques.godfroid@uit.no.
authors.forename: J
authors.initials: J
authors.lastname: Godfroid
mesh_terms: D000818:Animals; D002003:Brucella abortus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D002007:Brucellosis, Bovine / Q000453:epidemiology / Q000382:microbiology*; D002417:Cattle; D005838:Genotype; D016036:Seroepidemiologic Studies; D013636:Tanzania / Q000453:epidemiology