Browsing by Author "Zadoks, Ruth"

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Food Safety, Health Management, and Biosecurity Characteristics of Poultry Farms in Arusha City, Northern Tanzania, Along a Gradient of Intensification
(East African Health Research Commission, 2018) Sindiyo, Emmanuel; Maganga, Ruth; Thomas, Kate; Benschop, Jackie; Benschop, Jackie; Swai, Emmanuel; Shirima, Gabriel; Zadoks, Ruth
Background: With the growth, urbanisation, and changing consumption patterns of Tanzania’s human population, new livestock production systems are emerging. Intensification of poultry production may result in opportunities and threats for food safety, such as improved awareness of biosecurity or increasing prevalence of foodborne pathogens including non- typhoidal Salmonella or Campylobacter spp. We conducted a semiquantitative analysis of poultry production systems in northern Tanzania, with emphasis on biosecurity, health management practices, and prevalence of foodborne pathogens, to gain insight into potential associations between intensification and food safety. Methods: Interviews were conducted with managers of 40 poultry farms, with equal representation of 4 production sys- tems (extensive, semi-intensive, or intensive production with indigenous chickens, and broiler farming). Per farm, up to 10 birds (total, 386) were tested for cloacal shedding of nontyphoidal Salmonella, with a subset of farms tested for Campylobacter. Data were analysed using univariate statistics, and results were discussed during feedback workshops with participating farmers and extension officers. Results: Clear differences existed between farm types with regard to implementation of biosecurity and health manage- ment practices and use of extension services. By contrast, prevalence of foodborne pathogens (6 of 40 farms or 15% for nontyphoidal Salmonella and 13 of 26 farms or 50% for Campylobacter spp.) was not farm-type specific, indicating that it is driven by other factors. Across farming systems, knowledge and awareness of the presence of antimicrobials in poul- try feed and the need to abide by post-treatment withdrawal times were limited, as was access to impartial professional advice regarding treatment. Conclusion: Different control measures may be needed to protect poultry health compared to public health, and improvements in information provision may be needed for both.
Participatory mapping identifies risk areas and environmental predictors of endemic anthrax in rural Africa
(Springer Nature Limited, 2022-06-12) Aminu, Olubunmi; Forde, Taya; Ekwem, Divine; Nelli, Luca; Mmbaga, Blandina; Mshanga, Deogratius; Shand, Mike; Shirima, Gabriel; Walsh, Markus; Zadoks, Ruth; Biek, Roman; Lembo, Tiziana
Disease mapping reveals geographical variability in incidence, which can help to prioritise control efforts. However, in areas where this is most needed, resources to generate the required data are often lacking. Participatory mapping, which makes use of indigenous knowledge, is a potential approach to identify risk areas for endemic diseases in low- and middle-income countries. Here we combine this method with Geographical Information System-based analyses of environmental variables as a novel approach to study endemic anthrax, caused by the spore-forming bacterium Bacillus anthracis, in rural Africa. Our aims were to: (1) identify high-risk anthrax areas using community knowledge; (2) enhance our understanding of the environmental characteristics associated with these areas; and (3) make spatial predictions of anthrax risk. Community members from the Ngorongoro Conservation Area (NCA), northern Tanzania, where anthrax is highly prevalent in both animals and humans, were asked to draw areas they perceived to pose anthrax risks to their livestock on geo-referenced maps. After digitisation, random points were generated within and outside the defined areas to represent high- and low-risk areas, respectively. Regression analyses were used to identify environmental variables that may predict anthrax risk. Results were combined to predict how the probability of being a high- risk area for anthrax varies across space. Participatory mapping identified fourteen discrete high-risk areas ranging from 0.2 to 212.9 km 2 in size and occupying 8.4% of the NCA. Areas that pose a high risk of anthrax were positively associated with factors that increase contact with Bacillus anthracis spores rather than those associated with the pathogen’s survival: close proximity to inland water bodies, where wildlife and livestock congregate, and low organic carbon content, which may indicate an increased likelihood of animals grazing close to soil surface and ingesting spores. Predicted high-risk areas were located in the centre of the NCA, which is likely to be encountered by most herds during movements in search for resources. We demonstrate that participatory mapping combined with spatial analyses can provide novel insights into the geography of disease risk. This approach can be used to prioritise areas for control in low-resource settings, especially for diseases with environmental transmission.
Prevalence of Campylobacter and Salmonella in African food animals and meat: A systematic review and meta-analysis
(Elsevier, 2019-10-31) Thomas, Kate; de Glanville, William; Barker, Gary; Benschop, Jackie; Buza, Joram; Cleaveland, Sarah; Davis, Margaret; Mmbaga, Blandina; Prinsen, Gerard; Swai, Emmanuel; Zadoks, Ruth; Crump, John
Background: Campylobacter and Salmonella, particularly non-typhoidal Salmonella, are important bacterial en- teric pathogens of humans which are often carried asymptomatically in animal reservoirs. Bacterial foodborne infections, including those derived from meat, are associated with illness and death globally but the burden is disproportionately high in Africa. Commercial meat production is increasing and intensifying in many African countries, creating opportunities and threats for food safety. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, we searched six databases for English language studies published through June 2016, that reported Campylobacter or Salmonella carriage or infection prevalence in food animals and contamination prevalence in food animal products from African countries. A random effects meta-analysis and multivariable logistic re- gression were used to estimate the species-specific prevalence of Salmonella and Campylobacter and assess re- lationships between sample type and region and the detection or isolation of either pathogen. Results: Seventy-three studies reporting Campylobacter and 187 studies reporting Salmonella across 27 African countries were represented. Adjusted prevalence calculations estimate Campylobacter detection in 37.7% (95% CI 31.6–44.3) of 11,828 poultry samples; 24.6% (95% CI 18.0–32.7) of 1975 pig samples; 17.8% (95% CI 12.6–24.5) of 2907 goat samples; 12.6% (95% CI 8.4–18.5) of 2382 sheep samples; and 12.3% (95% CI 9.5–15.8) of 6545 cattle samples. Salmonella were detected in 13.9% (95% CI 11.7–16.4) of 25,430 poultry samples; 13.1% (95% CI 9.3–18.3) of 5467 pig samples; 9.3% (95% CI 7.2–12.1) of 2988 camel samples; 5.3% (95% CI 4.0–6.8) of 72,292 cattle samples; 4.8% (95% CI 3.6–6.3) of 11,335 sheep samples; and 3.4% (95% CI 2.2–5.2) of 4904 goat samples. ‘External’ samples (e.g. hide, feathers) were significantly more likely to be contaminated by both pathogens than ‘gut’ (e.g. faeces, cloaca) while meat and organs were significantly less likely to be contaminated than gut samples. Conclusions: This study demonstrated widespread prevalence of Campylobacter species and Salmonella serovars in African food animals and meat, particularly in samples of poultry and pig origin. Source attribution studies could help ascertain which food animals are contributing to human campylobacteriosis and salmonellosis and direct potential food safety interventions.