Browsing by Author "Bwatota, Shedrack"

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Brucella Species Circulating in Smallholder Dairy Cattle in Tanzania
(MDPI, 2024-09-21) Mengele, Isaac; Akoko, James; Shirima, Gabriel; Bwatota, Shedrack; Motto, Shabani; Hernandez-Castro, Luis; Komwihangilo, Daniel; Lyatuu, Eliamoni; de Clare Bronsvoort, Barend; Cook, Elizabeth
Brucellosis is a zoonosis caused by bacteria of the genus Brucella, which results in economic losses relating to livestock and threatens public health. A cross-sectional study was conducted to determine the molecular prevalence of Brucella species in smallholder dairy cattle in six regions of Tanzania from July 2019 to October 2020. Dairy cattle (n = 2048) were sampled from 1371 farms. DNA extracted from blood and vaginal swabs was tested for Brucella using qPCR targeting the IS711 gene and positives were tested for the alkB marker for B. abortus and BMEI1172 marker for B. melitensis. The molecular prevalence was 3.5% (95% CI: 2.8–4.4) with the highest prevalence 8.1% (95% CI: 4.6–13.0) in Njombe region. B. melitensis was the predominant species detected (66.2%). Further studies are recommended to understand the source of B. melitensis and its implications for veterinary public health. Livestock keepers should be informed of the risks and biosecurity practices to reduce the introduction and control of Brucella. Cattle and small ruminant vaccination programs could be implemented to control brucellosis in high-risk populations in the country.
Epidemiologic study of q fever in smallholder dairy cattle in selected regions of Tanzania
(NM-AIST, 2023-08-20) Bwatota, Shedrack
A cross-sectional study was conducted to determine prevalence and the risk factors associated with Coxiella burnetii seropositivity in smallholder dairy cattle in six regions from the southern highland and northern zones of Tanzania between July 2019 and October 2020. A total of 2049 blood samples and 1920 vaginal swabs were collected from dairy cattle. Serum was tested for antibodies against C. burnetii using an indirect enzyme-linked immunosorbent assay (ELISA). C. burnetii DNA was identified from vaginal swabs using quantitative polymerase chain reaction (qPCR) analyses. A questionnaire survey was designed and uploaded to the Open Data Kit (ODK) cloud platformsoftware version 1.22.4. At each household, the cattle owner aging equal or over 18 years was interviewed to understand the risk factors related to animal health, husbandry, and farmer socioeconomics, as well as environmental variables. C. burnetii prevalence was calculated at different epidemiological levels and maps were created to visualize Q fever spatial distribution. Logistic generalized linear mixed effects models were built to explorethe association between ELISA binomial results, and a set of risk factors and environmental variables important for C. burnetii occurrence. An overall animal seroprevalence of 3.86% (79, 2049) 95% CI 3.06 - 4.78 was estimated across the study regions. Among these regions, Tanga (northern zone) and Iringa (southern zone) showed the highest prevalence with 8.21% (95% CI 6.0 - 10.89%) and 4.63% (95% CI: 2.49 - 7.78%) respectively. On the other hand, molecular identification of C. burnetii from vaginal swabs of selected cows revealed an overall prevalence of 0.94% (18,1920) (95% CI 0.5-1.4%). Among the northern zone regions, Arusha had the highest of 2.3%(95%CI 0.9-4.7%) and on the southern highlands zone, Iringa emanated to have the highest prevalence of 0.73% (95%CI 0.08-2.5%). Animal age, extensive feeding system, and temperature were univariably significant risk factors to C. burnetii seropositivity. The final multivariable logistic regression model showed that old animal age, extensive feeding system, and low precipitation were strongly associated with Q fever seropositivity. These findings indicate that C. burnetii circulates among smallholder dairy cattle across regions in Tanzania. However, Tanga, Arusha and Iringa are the three regions with the highest seroprevalence and should be considered for systematic and active surveillance. Furthermore, “One Health” approaches are necessary to fully understand disease transmission and control of this zoonotic disease.
Epidemiology of Q-fever in domestic ruminants and humans in Africa. A systematic review
(CABI One Health, 2022-11-17) Bwatota, Shedrack; Cook, Elizabeth; Bronsvoort, Barend; Wheelhouse, Nick; Hernandez-Castro, Luis; Shirima, Gabriel
Q-fever is a zoonotic infectious disease caused by the gram-negative, intracellular, spore-forming bacterium Coxiella burnetii . Infected ruminants (cattle, sheep, and goats) are the reservoirs of the pathogen and thus an important source of infection in humans. This systematic review aims to consolidate the knowledge and awareness of Q-fever in Africa and identify future research opportunities and possible interventions in low-resource settings. We review information on Q-fever epidemiology and the diagnostic challenges in humans and domestic ruminants in Africa from the last 23 years. Six databases including university repositories were searched for relevant articles. A total of 84 studies and 4 theses met the selection criteria and were thus included in the review. They include serological and molecular studies of Q-fever in humans or domestic ruminants in 24/54 African countries. The mean seroprevalence estimates were 16% (95%CI 11–23%) in humans; 14% (95%CI 10–20%) in cattle; 13% (95%CI 9–18%) in sheep; and 21% (95%CI 15–29%) in goats. The mean prevalence for molecular detection of the pathogen were 3% (95%CI 0–16%) in humans; 9% (95%CI 4–19%) in cattle; 16% (95%CI 5–41%) in sheep; and 23% (95%CI 20–80%) in goats. The number of studies that identified risk factors for exposure among domestic ruminants was: sex (n = 6), age (n = 17), contact with other animals (n = 5), lack of quarantine of newly purchased animals (n = 1), extensive grazing system (n = 4), herd size (2), history of abortion (n = 5), absence of vaccination (n = 2), and high temperature (n = 1). The number of studies that reported protective factors was: sanitation (n = 2), burying and/ or burning the aborted foetus (n = 2), and young (age) (n = 2). The studies that identified risk factors for human disease infection included: close contact to animals (n = 7), age (n = 3), and gender (n = 5), while those identifying protective factors included: living in non-irrigated areas (n = 1), awareness/knowledge about zoonosis (n = 1), rodent control (n = 1), sanitation/disinfection of equipment after and before use (n = 1), occasional grazing (n = 1), and do nothing to aborted materials (n = 1). Diagnostic challenges such as poverty, lack of a well-equipped laboratory with biosafety level 3 specific for Q-fever testing, unspecific and self-limiting clinical signs/symptoms, lack of gold standard test, and variation in test specificity and sensitivity were identified. The disease is likely to be widespread in Africa and of public importance and underreported thus ‘One Health’ approaches to future studies are recommended. Further studies should focus on concurrent studies of human and livestock populations.
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.
Genetic estimates and genome-wide association studies of antibody response in Tanzanian dairy cattle
(Frontiers Media SA, 2025-04-24) Hernandez-Castro, Luis; Cook, Elizabeth; Matika, Oswald; Mengele, Isaac; Motto, Shabani; Bwatota, Shedrack; Zirra-Shallangwa, Bibiana; Pong-Wong, Ricardo; Prendergast, James; Mrode, Raphael; Toye, Philip; Komwihangilo, Daniel; Lyatuu, Eliamoni; Karani, Benedict; Nangekhe, Getrude; Mwai, Ally; Shirima, Gabriel; Bronsvoort, Barend
Identifying the genetic determinants of host defence against infectious pathogens is central to enhancing disease resilience and therapeutic efficacy in livestock. Here, we investigated immune response heritability to important infectious diseases affecting smallholder dairy cattle using variance component analysis. We also conducted genome-wide association studies (GWAS) to identify genetic variants that may help understand the underlying biology of these health traits. By assessing 668,911 single-nucleotide polymorphisms (SNPs) genotyped in 2,045 crossbred cattle sampled from six regions of Tanzania, we identified high levels of interregional admixture and European introgression, which may increase infectious disease susceptibility relative to indigenous breeds. Heritability estimates were low to moderate, ranging from 0.03 (SE ± 0.06) to 0.44 (SE ± 0.07), depending on the health trait. GWAS results revealed several loci associated with seropositivity to the viral diseases Rift Valley fever and bovine viral diarrhoea, the protozoan parasites Neospora caninum and Toxoplasma gondii, and the bacterial pathogens Brucella sp, Leptospira hardjo, and Coxiella burnetii. The identified quantitative trait loci mapped to genes involved in immune defence, tumour suppression, neurological processes, and cell exocytosis. We propose that our results provide a basis for future understanding of the cellular pathways contributing to general and taxon-specific infection responses, and for advancing selective breeding and therapeutic target design.
Seroepidemiology of Leptospira serovar Hardjo and associated risk factors in smallholder dairy cattle in Tanzania
(PLOS ONE, 2023-04-05) Motto, Shabani; Hernandez-Castro, Luis; Shirima, Gabriel; Mengele, Isaac; Bwatota, Shedrack; Bronsvoort, Barend; Lyatuu, Eliamoni; Komwihangilo, Daniel; Cook, Elizabeth
Background Smallholder dairy farming is crucial for the Tanzanian dairy sector which generates income and employment for thousands of families. This is more evident in the northern and southern highland zones where dairy cattle and milk production are core economic activities. Here we estimated the seroprevalence of Leptospira serovar Hardjo and quantified potential risk factors associated with its exposure in smallholder dairy cattle in Tanzania. Methods From July 2019 to October 2020, a cross-sectional survey was carried out in a subset of 2071 smallholder dairy cattle. Information about animal husbandry and health management was collected from farmers, and blood was taken from this subset of cattle. Seroprevalence was estimated and mapped to visualize potential spatial hotspots. The association between a set of animal husbandry, health management and climate variables and ELISA binary results was explored using a mixed effects logistic regression model. Results An overall seroprevalence of 13.0% (95% CI 11.6–14.5%) for Leptospira serovar Hardjo was found in the study animals. There was marked regional variations with the highest seroprevalence in Iringa 30.2% (95% CI 25.1–35.7%) and Tanga 18.9% (95% CI 15.7–22.6) with odds ratios of OR = 8.13 (95% CI 4.23–15.63) and OR = 4.39 (95% CI 2.31–8.37), respectively. Multivariate analysis revealed the individual animal factors that were a significant risk for Leptospira seropositivity in smallholder dairy cattle were: animals over 5 years of age (OR = 1.41, 95% CI 1.05–1.9); and indigenous breed (OR = 2.78, 95% CI 1.47–5.26) compared to crossbred animals SHZ-X-Friesian (OR = 1.48, 95% CI 0.99–2.21) and SHZ-X-Jersey (OR = 0.85, 95% CI 0.43–1.63). Farm management factors significantly associated with Leptospira seropositivity included: hiring or keeping a bull for raising purposes (OR = 1.91, 95% CI 1.34–2.71); distance between farms of more than 100 meters (OR = 1.75, 95% CI 1.16–2.64); cattle kept extensively (OR = 2.31, 95% CI 1.36–3.91); farms without cat for rodent control (OR = 1.87, 95% CI 1.16–3.02); farmers with livestock training (OR = 1.62, 95% CI 1.15–2.27). Temperature (OR = 1.63, 95% CI 1.18–2.26), and the interaction of higher temperature and precipitation (OR = 1.5, 95%CI 1.12–2.01) were also significant risk factors. Conclusion This study indicated seroprevalence of Leptospira serovar Hardjo, as well as the risk factors driving dairy cattle leptospirosis exposure in Tanzania. The study showed an overall high leptospirosis seroprevalence with regional variations, where Iringa and Tanga represented the highest seroprevalence and risk. The study highlighted the urgent need to understand the human exposures and risks from this important zoonosis to develop control measures and awareness of the problem and quantify the economic and production impacts through abortion and milk loss. In addition, given that the available data was limited to Leptospira serovar Hardjo, the study recommends more studies to identify serologically the most common serovars in cattle for targeted vaccination and risk reduction.
Seroprevalence and Risk Factors for Q fever (Coxiella burnetii) Exposure in Smallholder Dairy Cattle in Tanzania
(MDPI, 2022-11-28) Bwatota, Shedrack; Shirima, Gabriel; Hernandez-Castro, Luis; Bronsvoort, Barend; Wheelhouse, Nick; Mengele, Isaac; Motto, Shabani; Komwihangilo, Daniel; Lyatuu, Eliamoni; Cook, Elizabeth
Q fever is a zoonotic disease, resulting from infection with Coxiella burnetii. Infection in cattle can cause abortion and infertility, however, there is little epidemiological information regarding the disease in dairy cattle in Tanzania. Between July 2019 and October 2020, a serosurvey was conducted in six high dairy producing regions of Tanzania. Cattle sera were tested for antibodies to C. burnetii using an indirect enzyme-linked immunosorbent assay. A mixed effect logistic regression model identified risk factors associated with C. burnetii seropositivity. A total of 79 out of 2049 dairy cattle tested positive with an overall seroprevalence of 3.9% (95% CI 3.06–4.78) across the six regions with the highest seroprevalence in Tanga region (8.21%, 95% CI 6.0–10.89). Risk factors associated with seropositivity included: extensive feeding management (OR 2.77, 95% CI 1.25–3.77), and low precipitation below 1000 mm (OR 2.76, 95% 1.37–7.21). The disease seroprevalence is relatively low in the high dairy cattle producing regions of Tanzania. Due to the zoonotic potential of the disease, future efforts should employ a “One Health” approach to understand the epidemiology, and for interdisciplinary control to reduce the impacts on animal and human health.
The Status and Risk Factors of Brucellosis in Smallholder Dairy Cattle in Selected Regions of Tanzania
(MDPI, 2023-02-14) Mengele, Isaac; Shirima, Gabriel; Bwatota, Shedrack; Motto, Shabani; Bronsvoort, Barend; Komwihangilo, Daniel; Lyatuu, Eliamoni; Cook, Elizabeth; Hernandez-Castro, Luis
Bovine brucellosis is a bacterial zoonoses caused by Brucella abortus. We conducted a cross-sectional study to determine brucellosis seroprevalence and risk factors among smallholder dairy cattle across six regions in Tanzania. We sampled 2048 dairy cattle on 1374 farms between July 2019 and October 2020. Sera were tested for the presence of anti-Brucella antibodies using a competitive enzyme-linked immunosorbent assay. Seroprevalence was calculated at different administrative scales, and spatial tests were used to detect disease hotspots. A generalized mixed-effects regression model was built to explore the relationships among Brucella serostatus, animals, and farm management factors. Seroprevalence was 2.39% (49/2048 cattle, 95% CI 1.7–3.1) across the study area and the Njombe Region represented the highest percentage with 15.5% (95% CI 11.0–22.0). Moreover, hotspots were detected in the Njombe and Kilimanjaro Regions. Mixed-effects models showed that having goats (OR 3.02, 95% C 1.22–7.46) and abortion history (OR 4.91, 95% CI 1.43–16.9) were significant risk factors for brucellosis. Education of dairy farmers regarding the clinical signs, transmission routes, and control measures for brucellosis is advised. A One Health approach is required to study the role of small ruminants in cattle brucellosis and the status of brucellosis in dairy farmers in the Njombe and Kilimanjaro Regions.