Browsing by Author "Tarimo, Rigobert"

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Field vaccination of locally-owned cattle against malignant catarrhal fever under environmentally challenging conditions in Tanzania
(Elsevier, 2025-01-25) Bainbridge, Samuel; Mappi, Tauta; Cleaveland, Sarah; Chubwa, Choby; Davis, Alicia; Grant, Dawn; Kibona, Tito; Bwatota, Shedrack; Larsen, Freja; Lyimo, Samson; Mshana, Fadhili; Percival, Ann; Shirima, Gabriel; Mtili, Bakari; Musyangi, Felix; Tarimo, Rigobert; Lankester, Felix; Russell, George
Malignant catarrhal fever (MCF), caused by alcelaphine herpesvirus-1 (AIHV-1) transmitted from wildebeest, is a lethal cattle disease with significant impacts on East African pastoralists. Development of a live attenuated MCF vaccine has prompted research into its use in communities at risk. This study reports results from the first utilisation of the MCF vaccine in locally-owned cattle under field conditions. The study involved a primary two-dose course vaccination of 1634 cattle, followed a year later, by boost vaccination of 385 of these cattle. It aimed to: (a) evaluate the antibody response to a two-dose AlHV-1 primary vaccination course, including initial response, antibody levels after one year, and clinical events post-vaccination; (b) assess how factors like age, reproductive status, body condition, and breed influence the initial response; and (c) compare antibody responses to single- and two-dose booster protocols one year after primary vaccination. Analyses were carried out using linear mixed-effects models and paired t-tests. Clinical incidents were reported in 11/1634 cattle vaccinated during the primary course and in 0/385 cattle during the boost regimens. The primary vaccination resulted in a 9-fold increase in comparison to pre-vaccination antibody levels and the response was consistent across animals of different ages, reproductive statuses and body conditions. While antibody levels declined 11 months after primary vaccination, they remained high, and a single-dose booster vaccination was sufficient to elicit a strong immune response, with only marginal increases after a second booster. The study provides evidence of high immunogenicity and low incidences of clinical events of the vaccine in cattle across individual host factors and immunologically vulnerable groups, under prevailing environmental conditions. It also indicates the utility of a single-dose booster regimen. These findings will support progress towards commercial production and larger-scale adoption which could generate important benefits for the livelihoods, and sustainability of pastoral livestock systems.
Molecular detection and genetic characterization of Bartonella species from rodents and their associated ectoparasites from northern Tanzania
(PLOS ONE, 2019-10-15) Theonest, Ndyetabura; Carter, Ryan; Amani, Nelson; Doherty, Siaˆn; Hugho, Ephrasia; Keyyu, Julius; Mable, Barbara; Shirima, Gabriel; Tarimo, Rigobert; Thomas, Kate; Haydon, Daniel; Buza, Joram; Allan, Kathryn; Halliday, Jo
Background Bartonellae are intracellular bacteria, which can cause persistent bacteraemia in humans and a variety of animals. Several rodent-associated Bartonella species are human pathogens but data on their global distribution and epidemiology are limited. The aims of the study were to: 1) determine the prevalence of Bartonella infection in rodents and fleas; 2) identify risk factors for Bartonella infection in rodents; and 3) characterize the Bartonella genotypes present in these rodent and flea populations. Methods and results Spleen samples collected from 381 rodents representing six different species were tested for the presence of Bartonella DNA, which was detected in 57 individuals (15.0%; 95% CI 11.3–18.5), of three rodent species (Rattus rattus n = 54, Mastomys natalensis n = 2 and Paraxerus flavovottis n = 1) using a qPCR targeting the ssrA gene. Considering R. rattus individuals only, risk factor analysis indicated that Bartonella infection was more likely in reproductively mature as compared to immature individuals (OR = 3.42, p <0.001). Bartonella DNA was also detected in 53 of 193 Xenopsylla cheopis fleas (27.5%: 95% CI 21.3– 34.3) collected from R.rattus individuals. Analysis of ssrA and gltA sequences from rodent spleens and ssrA sequences from fleas identified multiple genotypes closely related (� 97% similar) to several known or suspected zoonotic Bartonella species, including B. tribocorum, B. rochalimae, B. elizabethae and B. quintana. Conclusions The ssrA and gltA sequences obtained from rodent spleens and ssrA sequences obtained from fleas reveal the presence of a diverse set of Bartonella genotypes and increase our understanding of the bartonellae present in Tanzanian. Further studies are needed to fully characterise the prevalence, genotypes and diversity of Bartonella in different host populations and their potential impacts on human health.
Molecular detection of Coxiella burnetii infection in small mammals from Moshi Rural and Urban Districts, northern Tanzania.
(John Wiley & Sons Ltd, 2020-12-05) Theonest, Ndyetabura; Carter, Ryan; Kasagama, Elizabeth; Keyyu, Julius; Tarimo, Rigobert; Thomas, Kate; Wheelhouse, Nick; Maro, Venance; Haydon, Daniel; Buza, Joram; Allan, Kathryn; Halliday, Jo
Coxiella burnetii is an obligate intracellular bacterium that causes Q fever, a zoonotic disease of public health importance. In northern Tanzania, Q fever is a known cause of human febrile illness, but little is known about its distribution in animal hosts. We used a quantitative real-time PCR (qPCR) targeting the insertion element IS1111 to determine the presence and prevalence of C. burnetii infections in small mammals trapped in 12 villages around Moshi Rural and Moshi Urban Districts, northern Tanzania. A total of 382 trapped small mammals of seven species were included in the study; Rattus rattus (n = 317), Mus musculus (n = 44), Mastomys natalensis (n = 8), Acomys wilson (n = 6), Mus minutoides (n = 3), Paraxerus flavovottis (n = 3) and Atelerix albiventris (n = 1). Overall, 12 (3.1%) of 382 (95% CI: 1.6-5.4) small mammal spleens were positive for C. burnetii DNA. Coxiella burnetii DNA was detected in five of seven of the small mammal species trapped; R. rattus (n = 7), M. musculus (n = 1), A. wilson (n = 2), P. flavovottis (n = 1) and A. albiventris (n = 1). Eleven (91.7%) of twelve (95% CI: 61.5-99.8) C. burnetii DNA positive small mammals were trapped within Moshi Urban District. These findings demonstrate that small mammals in Moshi, northern Tanzania are hosts of C. burnetii and may act as a source of C. burnetii infection to humans and other animals. This detection of C. burnetii infections in small mammals should motivate further studies into the contribution of small mammals to the transmission of C. burnetii to humans and animals in this region.