College of Veterinary and Medical Sciences
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Browsing College of Veterinary and Medical Sciences by Subject "Abortion"
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Item First isolation, identification, phenotypic and genotypic characterization of Brucella abortus biovar 3 from dairy cattle in Tanzania(2015) Mathew, C; Stokstad, M; Johansen, T. B; Klevar, S.; Mdegela, R. H.; Mwamengele, G.; Michel, P.; Escobar, L.; Fretin, D.; Godfroid, J.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.Item Reproductive infections in cattle in Tanzania – lessons for control priorities(SOJ Microbiol Infect Dis, 2017) Mathew, C; Klevar, S; Løken, T; Mwamengele, G; Skjerve, E; Godfroid, J; Stokstad, S; Mdegela, R. H.Reproductive disorders have negative impact on performance in cattle worldwide. Studies on infections causing reproductive disorders in Tanzania are few and fragmented, which complicates targeted disease prevention. To investigate the prevalence of selected infections and their associations with reproductive disorders and risk factors in cattle under different management systems, a cross-sectional study was conducted in two bordering regions in the southern highlands in Tanzania. Herd and individual animal level data were collected by direct observation and a semistructured questionnaire interview of the farmer. Sera from 658 cattle from 202 herds were analyzed using a commercial ELISA kits for antibodies to Bovine Viral Diarrhea Virus (BVDV), Brucella spp. and Neospora caninum. The logistic regression model identified herd size (odds ratio (OR): 14.5), location (OR: 23.1) and management system (grazing strategy) (OR: 22.7) as risk factors for Brucella spp. The same risk factors were also identified for BVDV herd size (OR: 2.8), location (OR: 12.7) and management system (OR: 2.9). History of abortion was associated with seropositivity for Brucella spp. (OR: 4.6). No risk factors, including location and presence of dogs, nor any association with reproductive disorders were identified for N. caninum. In one region the herd level sero-prevalence was 66.7% for BVDV and 36.1% for Brucella spp., while in the other it was 6.5% for BVDV and 0.6% for Brucella spp. In total, BVDV specific antibodies were found in 15.2% of the animals in 17.9% of the herds, and Brucella spp. specific antibodies were detected in 5.4% of the animals in 7.4% of the herds. Anti- N. caninum antibodies were found in 4.5% of animals in 8.4% of the herds. In conclusion, prevalence and impact of BVDV and Brucella spp. differed significantly between geographically closely related areas, most probably due to differences in management system that affects the potential for survival of the agents in the population. This shows that all control measures must be based on accurate epidemiological knowledge of the occurrence of the infection. Low-prevalence areas are highly susceptible for introduction of infection, while in the high-prevalence areas control measures must be implemented to reduce the impact and the risk of transferring Brucella spp. from livestock to humans.