Taenia solium cysticercosis in the unprocessed pork supply chain in Nairobi and environs, Kenya

The zoonotic parasite, Taenia solium, is a serious public health threat in countries where it is endemic. The larval stage of this parasite is responsible for porcine cysticercosis and neurocysticercosis in humans, which is one of the leading causes of seizures and epilepsy in developing countries. While documented studies have only been conducted in western areas of Kenya, other areas, including Nairobi, have not been investigated to fully understand the epidemiology of the parasite. Seven hundred blood samples were collected from randomly selected pigs presented for slaughter at the largest porcine abattoir supplying unprocessed pork to butcheries within Nairobi city and its surroundings. The samples were tested using an antigen ELISA to determine the prevalence of cysticercosis. Information regarding the pigs’ age, sex and source was obtained from the traders and pork destinations recorded

Urban Livestock Keeping in the City of Nairobi: Diversity of Production Systems, Supply Chains, and Their Disease Management and Risks

Urban livestock keeping in developing cities have an important role in food security and livelihoods but can also pose a significant threat to the environment and health of urban dwellers. The aim of this study was to identify the different livestock systems in Nairobi, their supply chains, and their management and food safety risks. Seven focus group discussions with livestock production officers in charge of each major Nairobi sub-county were conducted. Data were collected on the type of systems existing for each livestock species and their supply chains, disease management, food safety risks, and general husbandry and gender factors. Supply chain flow diagrams and thematic analysis of the data was done. Results of the study show a large variability of livestock keeping in Nairobi. The majority were small scale with: <5 dairy cows, 1-6 dairy goats, <10 small ruminants, <20 pigs, 200-500 broilers, 300-500 layers, <10 indigenous chickens, or <20 rabbits. Beef keeping was mainly described as a "by the way" system or done by traders to fatten animals for 3 month. Supply chain analysis indicated that most dairy farmers sold milk directly to consumers due to "lack of trust" of these in traders. Broiler and pig farmers sold mainly to traders but are dependent on few large dominating companies for their replacement or distribution of products. Selling directly to retailers or consumers (including own consumption), with backyard slaughtering, were important chains for small-scale pig, sheep and goat, and indigenous chicken keepers. Important disease risk practices identified were associated with consumption of dead and sick animals, with underground network of brokers operating for ruminant products. Qualified trained health managers were used mainly by dairy farmers, and large commercial poultry and pig farmers, while use of unqualified health managers or no treatment were common in small-scale farming. Control of urban livestock keepers was reported difficult due to their "feeling of being outlaws," "lack of trust" in government, "inaccessibility" in informal settlements, "lack of government funding," or "understaffing." Findings are useful for designing policies to help to control urban livestock production and minimize its associated health and environment risks

Evidence of co-exposure with Brucella spp, Coxiella burnetii, and Rift Valley fever virus among various species of wildlife in Kenya

Background Co-infection, especially with pathogens of dissimilar genetic makeup, may result in a more devastating impact on the host. Investigations on co-infection with neglected zoonotic pathogens in wildlife are necessary to inform appropriate prevention and control strategies to reduce disease burden in wildlife and the potential transmission of these pathogens between wildlife, livestock and humans. This study assessed co-exposure of various Kenyan wildflife species with Brucella spp, Coxiella burnetii and Rift Valley fever virus (RVFV). Methodology A total of 363 sera from 16 different wildlife species, most of them (92.6%) herbivores, were analysed by Enzyme-linked immunosorbent assay (ELISA) for IgG antibodies against Brucella spp, C. burnetii and RVFV. Further, 280 of these were tested by PCR to identify Brucella species. Results Of the 16 wildlife species tested, 15 (93.8%) were seropositive for at least one of the pathogens. Mean seropositivities were 18.9% (95% CI: 15.0–23.3) for RVFV, 13.7% (95% CI: 10.3–17.7) for Brucella spp and 9.1% (95% CI: 6.3–12.5) for C. burnetii. Buffaloes (n = 269) had higher seropositivity for Brucella spp. (17.1%, 95% CI: 13.0–21.7%) and RVFV (23.4%, 95% CI: 18.6–28.6%), while giraffes (n = 36) had the highest seropositivity for C. burnetii (44.4%, 95% CI: 27.9–61.9%). Importantly, 23 of the 93 (24.7%) animals positive for at least one pathogen were co-exposed, with 25.4% (18/71) of the positive buffaloes positive for brucellosis and RVFV. On molecular analysis, Brucella DNA was detected in 46 (19.5%, CI: 14.9–24.7) samples, with 4 (8.6%, 95% CI: 2.2–15.8) being identified as B. melitensis. The Fisher’s Exact test indicated that seropositivity varied significantly within the different animal families, with Brucella (p = 0.013), C. burnetii (p = <0.001) and RVFV (p = 0.007). Location was also significantly associated (p = <0.001) with Brucella spp. and C. burnetii seropositivities. Conclusion Of ~20% of Kenyan wildlife that are seropositive for Brucella spp, C. burnetii and RVFV, almost 25% indicate co-infections with the three pathogens, particularly with Brucella spp and RVFV

Using a value chain framework for food safety assessment of broiler and indigenous chicken meat systems of Nairobi

Purpose: Research on livestock food systems in developing countries remains limited, yet this context needs to be understood to investigate the epidemiology of zoonoses. The aim of this study was to use a value chain framework to characterize the broiler and indigenous chicken meat systems of Nairobi and their food safety risks. Methods: Using such a framework for food safety characterisation at system level is novel and has significant potential in developing countries. Data collection involved 18 focus group discussions and 236 interviews with various poultry meat value chain stakeholders in Nairobi. Analysis included chain mapping and identification of governance and food safety challenges. Results: The study identified 10 chain profiles, characterising the broiler and indigenous chicken systems, and production-retailing continuum. Food safety risks identified were related to lack of biosecurity, cold chain and access to water, poor cleaning and hygiene practices, consumption of sick animals, significant environmental contamination of by-products, and lack of inspection at farm slaughter. Large companies dominated the governance of the broiler system through the control of day-old chick production. Overall government control was relatively weak leading to minimal official regulatory enforcement. Large companies and brokers were identified as dominant groups in market information dissemination and price setting. No dominant group was identified for indigenous chicken profiles, farming being at household level for local consumption, with quasi non-existent regulations. Lack of industry association was system-wide, creating a barrier for access to capital. Other system barriers included lack of space and expertise, leading to poor infrastructure and limited ability to implement effective hygienic measures. Conclusions and relevance: Optimal food safety and disease control strategies should consider the structure of the poultry meat system and stakeholder interactions to ensure effective programmes. This study provides a new perspective for epidemiologists and public health officers to address food safety risks in full understanding of the food system context

Value chain analysis as a tool for assessing food safety risks in the Nairobi pork food system

In Nairobi, with 3.1 million consumers and 30,000 pigs, the pork system may represents a major source of zoonotic pathogens. Yet, this system and its public health risks have not been described. The study used value chain analysis, a well-known method in economics, to investigate zoonosis and food safety risks practices in the Nairobi pork food system. A cross-sectional study of the Nairobi pork system collected data through 25 focus group discussions and 436 individual interviews with farmers, traders, abattoir owners, large companies’ managers, retailers, government officers and consumers. Data were analysed to identify, describe and quantify the main pork chain profiles, their associated zoonosis and food safety risks practices and their link to governance, the distribution of benefits and barriers to improving the system. Six pork chain profiles were identified with the ‘large integrated company’ profile accounting for 62% of pork marketed through abattoirs. Pigs in slums were channelled directly to consumers and butchers or through less integrated markets. Main zoonosis and food safety risk practices for city pig keepers were: handling and consumption of sick pigs; and swill and scavenging feeding. In less integrated abattoirs these risks were: lack of traceability, cold chain systems and adequate cleaning and sterilising practices and equipment. For the retailers, there was a lack of hygiene linked to poor infrastructure, scarcity of water and cleaning practices. Large companies govern the high end market for pork where barriers to improvements were less. In the lower end poor profit margins and unequal benefit distribution led to issues on around investments in infrastructure, cold chains and human capacity building plus difficulties with meeting feeding and animal health costs. Conclusions This study identified the main zoonoses and food safety risk practices and the people involved in risk taking activities to help future control programmes in the Nairobi pork system. The integration of value chain and analysis of risks practices proved useful and represent the way forward for epidemiologist working in developing countries

Ecological and subject-level drivers of interepidemic Rift Valley fever virus exposure in humans and livestock in Northern Kenya

Nearly a century after the first reports of Rift Valley fever (RVF) were documented in Kenya, questions on the transmission dynamics of the disease remain. Specifically, data on viral maintenance in the quiescent years between epidemics is limited. We implemented a cross-sectional study in northern Kenya to determine the seroprevalence, risk factors, and ecological predictors of RVF in humans and livestock during an interepidemic period. Six hundred seventy-six human and 1,864 livestock samples were screened for anti-RVF Immunoglobulin G (IgG). Out of the 1,864 livestock samples tested for IgG, a subset of 1,103 samples was randomly selected for additional testing to detect the presence of anti-RVFV Immunoglobulin M (IgM). The anti-RVF virus (RVFV) IgG seropositivity in livestock and humans was 21.7% and 28.4%, respectively. RVFV IgM was detected in 0.4% of the livestock samples. Participation in the slaughter of livestock and age were positively associated with RVFV exposure in humans, while age was a significant factor in livestock. We detected significant interaction between rainfall and elevation's influence on livestock seropositivity, while in humans, elevation was negatively associated with RVF virus exposure. The linear increase of human and livestock exposure with age suggests an endemic transmission cycle, further corroborated by the detection of IgM antibodies in livestock