Biosecurity in Village and Other Free-Range Poultry-Trying to Square the Circle?

Village poultry commonly suffer significant disease related losses and a plethora of biosecurity measures is widely advocated as a means to reduce morbidity and mortality. This paper uses a household economy perspective to assess some "economic" considerations determining biosecurity investments of village poultry keepers. It draws on the 2012/13 Tanzania National Panel Survey (TZ-NPS), which covered 1,228 poultry-keeping households. Disease was the most frequently reported cause of bird losses and, in the majority of households, accounted for more than half of reported bird losses. However, given that poultry rarely contributed more than 10% to total annual household income, for 95% of households the value of birds lost to disease represented <10% of annual income. The value placed on poultry within households may vary by gender and the overall figure may mask differential intra-household impacts. The break-even cost for various levels of reduction of disease losses is estimated using a partial budget analysis. Even if achieved at no cost, a 75% reduction in disease-associated mortality would only result in a one percent increase of annual household income. Thus, to the "average" village poultry-keeping household, investments in poultry may not be of high priority, even when cost-effective. Where risks of disease spread impact on the wider community and generate significant externalities, poultry keepers must be supported by wider societal actions rather than being expected to invest in biosecurity for purely personal gain.

Participatory Epidemiology: Principles, Practice, Utility, and Lessons Learnt.

Participatory epidemiology (PE) evolved as a branch of veterinary epidemiology and has been largely employed for the control and early warning of infectious diseases within resource-limited settings. It was originally based on combining practitioner communication skills with participatory methods to facilitate the involvement of animal caretakers and owners (embracing their knowledge, experience, and motivations) in the identification and assessment of animal disease problems, including in the design, implementation, monitoring and evaluation of disease control programs, policies, and strategies. With the importance of understanding social perceptions and drivers receiving increasing recognition by epidemiologists, PE tools are being adapted for an increasingly wide range of settings and endeavors. More recently, PE tools have been adapted for use in food and nutrition security programs, One Health activities, wildlife disease surveillance and as part of mixed-methods research across a range of socio-economic settings. This review describes the evolution of PE (in relation to veterinary epidemiology and briefly in relation to public health epidemiology), the underpinning philosophy and principles essential to its effective application and the importance of gender-sensitive approaches and data triangulation, including conventional confirmatory testing. The article also provides illustrative examples highlighting the diversity of approaches and applications of PE, hallmarks of successful PE initiatives and the lessons we can learn when these are missing. Finally, we look forward, describing the particular utility of PE for dealing with emerging infectious diseases, gaining attention of field-level cross-sector officials who can escalate concerns to a higher level and for continuing to raise the voices of those less-heard (such as women, minority groups, and remote communities with limited exposure to formal education) in defining the problems and planning activities that will likely impact directly on their well-being and livelihoods.

Determinants of diarrhoeal diseases and height-for-age z-scores in children under five years of age in rural central Tanzania.

INTRODUCTION: Childhood diarrhoeal diseases and stunting are major health problems in low- and middle-income countries (LMICs). Poor water supply, sanitation services and hygiene, frequently encountered in resource-poor settings, contribute to childhood diarrhoea and stunting. METHODS: Data on demographic characteristics, hygiene practices, sanitation and human-animal interactions (predictors) and child height-for-age z-scores (HAZ) (outcome) were collected once, while diarrhoea incidences were collected fortnightly for 24 months (outcome). RESULTS: Drinking water from public taps (OR = 0.51, 95% CI. 0.44-0.61; p < 0.001) and open wells (OR = 0.46, 95% CI. 0.39-0.54; p < 0.001) and older age of children (OR = 0.43, 95% CI. 0.27-0.67; p < 0.001) were protective against diarrhoea. Inappropriate disposal of children's faeces (OR = 1.15, 95% CI. 1.02-1.31; p = 0.025), sharing water sources with animals in the dry season (OR = 1.48, 95% CI. 1.29-1.70; p < 0.001), overnight sharing of houses with cats (OR = 1.35, 95% CI. 1.16-1.57; p < 0.001) and keeping chickens inside the house overnight regardless of room (OR = 1.39, 95% CI. 1.20-1.60; p < 0.001) increased the risk of diarrhoea. The Sukuma language group (p = 0.005), washing hands in running water (p = 0.007), access of chickens to unwashed kitchen utensils (p = 0.030) and overnight sharing of the house with sheep (p = 0.020) were associated with higher HAZ in children. CONCLUSIONS: Until a more precise understanding of the key risk factors is available, these findings suggest efforts towards control of diarrhoea and improved linear growth in these areas should be directed to increased access to clean and safe water, hand-washing, sanitation, and improved animal husbandry practices.

Diversity of two Theileria parva CD8+ antigens in cattle and buffalo-derived parasites in Tanzania.

Theileria parva is a tick-transmitted protozoan parasite that causes a disease called East Coast fever (ECF) in cattle. This important tick borne-disease (TBD) causes significant economic losses in cattle in many sub-Saharan countries, including Tanzania. Cattle immunization using Muguga cocktail has been recommended as an effective method for controlling ECF in pastoral farming systems in Tanzania. However, immunity provided through immunization is partially strain-specific. Therefore, the control of ECF in Tanzania is still a challenge due to inadequate epidemiological information. This study was conducted to assess genetic diversity of Tp1 and Tp2 genes from T. parva isolates that are recognized by CD8 + T-cells in cattle and buffalo. The Tp1 and Tp2 genes are currently under evaluation as candidates for inclusion in a subunit vaccine. A total of 130 blood samples collected from cattle which do not interact with buffalo (98), cattle co-grazing with buffalo (19) and buffalo (13) in Mara, Mbeya, Morogoro, Tanga, and Coast regions in Tanzania were used in this study. Genomic DNA was extracted from the blood samples, Tp1 and Tp2 genes were amplified using nested PCR and the PCR products were purified and sequenced. The partial sequencing of the Tp1 and Tp2 genes from T. parva isolates exhibited polymorphisms in both loci, including the epitope-containing regions. Results for sequence analysis showed that the overall nucleotide polymorphism (π) was 0.7% and 13.5% for Tp1 and Tp2, respectively. The Tajima's D and Fu's Fs test showed a negative value for both Tp1 and Tp2 genes, indicating deviations from neutrality due to a recent population expansion. The study further revealed a low to high level of genetic differentiations between populations and high genetic variability within populations. The study also revealed that most samples from the seven populations possessed several epitopes in antigens that were identical to those in the T. parva Muguga reference stock, which is the main component of the widely used live vaccine cocktail. Therefore, different strategic planning and cost-effective control measures should be implemented in order to reduce losses caused by ECF in the study areas.

Infection, colonization and shedding of Campylobacter and Salmonella in animals and their contribution to human disease: A review.

Livestock meat and offal contribute significantly to human nutrition as sources of high-quality protein and micronutrients. Livestock products are increasingly in demand, particularly in low- and middle-income settings where economies are growing and meat is increasingly seen as an affordable and desirable food item. Demand is also driving intensification of livestock keeping and processing. An unintended consequence of intensification is increased exposure to zoonotic agents, and a contemporary emerging problem is infection with Campylobacter and Salmonella spp. from livestock (avian and mammalian), which can lead to disease, malabsorption and undernutrition through acute and chronic diarrhoea. This can occur at the farm, in households or through the food chain. Direct infection occurs when handling livestock and through bacteria shed into the environment, on food preparation surfaces or around the house and surroundings. This manuscript critically reviews Campylobacter and Salmonella infections in animals, examines the factors affecting colonization and faecal shedding of bacteria of these two genera as well as risk factors for human acquisition of the infection from infected animals or environment and analyses priority areas for preventive actions with a focus on resource-poor settings.

Family poultry: Multiple roles, systems, challenges, and options for sustainable contributions to household nutrition security through a planetary health lens.

Achieving sustainable production of eggs by family poultry production systems that meet both environmental health and welfare standards is a complex endeavour. Humans have been raising different species of poultry for thousands of years across many different agroecological zones. The Food and Agriculture Organization of the United Nations has identified four different family poultry production systems: small extensive, extensive, semi-intensive, and intensive. Each of these systems varies in terms of inputs, outputs, gender dimensions, poultry health and welfare, and environmental impacts. This paper addresses key issues associated with the production of family poultry eggs in support of both improved maternal and child nutrition and sustainable, nutrition-sensitive agricultural practices. It provides an overview of the history of poultry raising; characteristics of the different family poultry production systems; challenges and solutions to poultry production in low- and middle-income countries; poultry husbandry (including breeds, nutrition, and shelter); infectious disease prevention and control in line with national and international animal health regulations; and food safety (microbial pathogens, toxins, and egg storage). To ensure that bird, human, and environmental health can flourish, it is essential for interdisciplinary research and development teams to work in collaboration with communities to ensure the long-term environmental and economic sustainability of family poultry production enterprises that are a good fit with local circumstances.

The chicken or the egg? Exploring bi-directional associations between Newcastle disease vaccination and village chicken flock size in rural Tanzania.

Newcastle disease (ND) is a viral disease of poultry with global importance, responsible for the loss of a potential source of household nutrition and economic livelihood in many low-income food-deficit countries. Periodic outbreaks of this endemic disease result in high mortality amongst free-ranging chicken flocks and may serve as a disincentive for rural households to invest time or resources in poultry-keeping. Sustainable ND control can be achieved through vaccination using a thermotolerant vaccine administered via eyedrop by trained "community vaccinators". This article evaluates the uptake and outcomes of fee-for-service ND vaccination programs in eight rural villages in the semi-arid central zone of Tanzania. It represents part of an interdisciplinary program seeking to address chronic undernutrition in children through improvements to existing poultry and crop systems. Newcastle disease vaccination uptake was found to vary substantially across communities and seasons, with a significantly higher level of vaccination amongst households participating in a longitudinal study of children's growth compared with non-participating households (p = 0.009). Two multivariable model analyses were used to explore associations between vaccination and chicken numbers, allowing for clustered data and socioeconomic and cultural variation amongst the population. Results demonstrated that both (a) households that undertook ND vaccination had a significantly larger chicken flock size in the period between that vaccination campaign and the next compared with those that did not vaccinate (p = 0.018); and (b) households with larger chicken flocks at the time of vaccination were significantly more likely to participate in vaccination programs (p < 0.001). Additionally, households vaccinating in all three vaccination campaigns held over 12 months were identified to have significantly larger chicken flocks at the end of this period (p < 0.001). Opportunities to understand causality and complexity through quantitative analyses are limited, and there is a role for qualitative approaches to explore decisions made by poultry-keeping households and the motivations, challenges and priorities of community vaccinators. Evidence of a bi-directional relationship, however, whereby vaccination leads to greater chicken numbers, and larger flocks are more likely to be vaccinated, offers useful insights into the efficacy of fee-for-service animal health programs. This article concludes that attention should be focused on ways of supporting the participation of vulnerable households in ND vaccination campaigns, and encouraging regular vaccination throughout the year, as a pathway to strengthen food security, promote resilience and contribute to improved human nutrition.

Occurrence of Ticks in Cattle in the New Pastoral Farming Areas in Rufiji District, Tanzania.

Ticks and tick-borne diseases plus trypanosomosis are a constraint to cattle rearing in Tanzania. Rufiji district was not known for important ticks infesting cattle because inhabitants were not engaged in keeping livestock. Not only has settlement of pastoralists and cattle in Rufiji increased the number of cattle but also cattle have been the source of bringing in and spreading of ticks. This study investigated tick species that have been introduced and managed to establish themselves in the new livestock farming areas in cattle in Rufiji. Tick distribution study was undertaken in three villages of Chumbi ward seasonally in 2009, 2011, and 2012. The identified ticks were Amblyomma variegatum (56.10%), Rhipicephalus evertsi (10.25%), R. microplus (27.40%), and R. appendiculatus (6.19%) out of 12940 ticks. Results indicate that ticks are present in the new livestock settlement areas. The occurrence of ticks is correlated with the recent settlement of cattle in the district.

Population genetic analysis of Theileria parva isolated in cattle and buffaloes in Tanzania using minisatellite and microsatellite markers.

A population genetic study of Theileria parva was conducted on 103 cattle and 30 buffalo isolates from Kibaha, Lushoto, Njombe Districts and selected National parks in Tanzania. Bovine blood samples were collected from these study areas and categorized into 5 populations; Buffalo, Cattle which graze close to buffalo, Kibaha, Lushoto and Njombe. Samples were tested by nested PCR for T. parva DNA and positives were compared for genetic diversity to the T. parva Muguga vaccine reference strain, using 3micro and 11 minisatellite markers selected from all 4 chromosomes of the parasite genome. The diversity across populations was determined by the mean number of different alleles, mean number of effective alleles, mean number of private allele and expected heterozygosity. The mean number of allele unique to populations for Cattle close to buffalo, Muguga, Njombe, Kibaha, Lushoto and Buffalo populations were 0.18, 0.24, 0.63, 0.71, 1.63 and 3.37, respectively. The mean number of different alleles ranged from 6.97 (Buffalo) to 0.07 (Muguga). Mean number of effective alleles ranged from 4.49 (Buffalo) to 0.29 (Muguga). The mean expected heterozygosity were 0.07 0.29, 0.45, 0.48, 0.59 and 0.64 for Muguga, cattle close to buffalo, Kibaha, Njombe, Lushoto and Buffalo populations, respectively. The Buffalo and Lushoto isolates possessed a close degree of diversity in terms of mean number of different alleles, effective alleles, private alleles and expected heterozygosity. The study revealed more diversity in buffalo isolates and further studies are recommended to establish if there is sharing of parasites between cattle and buffaloes which may affect the effectiveness of the control methods currently in use.