Aims: To determine the prevalence and levels of zoonotic agents in livestock wastes. Methods and Results: A proportionally weighted survey was undertaken and livestock waste samples analysed quantitatively for Escherichia coli O157, pathogenic Listeria, Salmonella, Campylobacter, Giardia and Cryptosporidium. A significant proportion of wastes contained at least one zoonotic agent. Relationships were found between dry matter content and the presence and levels of some zoonotic agents. Conclusions: British livestock wastes contain measurable levels of the zoonotic agents that cause most cases of gastroenteritis in the UK. Significance and Impact of the Study: Animal wastes are disposed of by spreading to agricultural land used for the production of crops and livestock grazing. As British wastes are contaminated with significant levels of zoonotic agents, the practice may represent a way for pathogens to travel further up the food chain.

Survey results describing the levels and prevalences of zoonotic agents in 1,549 livestock waste samples were analyzed for significance with livestock husbandry and farm waste management practices. Statistical analyses of survey data showed that livestock groups containing calves of <3 months of age, piglets, or lambs had higher prevalences and levels of Campylobacter spp. and Escherichia coli O157 in their wastes. Younger calves that were still receiving milk, however, had significantly lower levels and prevalence of E. coli O157. Furthermore, when wastes contained any form of bedding, they had lowered prevalences and levels of both pathogenic Listeria spp. and Campylobacter spp. Livestock wastes generated by stock consuming a diet composed principally of grass were less likely to harbor E. coli O157 or Salmonella spp. Stocking density did not appear to influence either the levels or prevalences of bacterial pathogens. Significant seasonal differences in prevalences were detected in cattle wastes; Listeria spp. were more likely to be isolated in March to June, and E. coli O157 was more likely to be found in May and June. Factors such as livestock diet and age also had significant influence on the levels and prevalences of some zoonotic agents in livestock wastes. A number of the correlations identified could be used as the basis of a best-practice disposal document for farmers, thereby lowering the microbiological risks associated with applying manures of contaminated livestock to land.

In response to reports that the contamination of food can occur during the on-farm primary phase of food production, we report data that describes a possible cost-effective intervention measure. The effect of time before soil incorporation of livestock wastes spread to land on the rate of decline of zoonotic agents present in the waste was investigated. Fresh livestock wastes were inoculated with laboratory-cultured Salmonella, Listeria, and Campylobacter spp. and Escherichia coli O157 before they were spead onto soil. Incorporation of the spread wastes was either immediate, delayed for 1 week, or did not occur at all. Bacterial decline was monitored over time and found to be significantly more rapid for all waste types when they were left on the soil surface. There were no significant differences in initial bacterial decline rates when wastes were spread in summer or winter. Our results indicate that not incorporating contaminated livestock wastes into soil is a potential intervention measure that may help to limit the spread of zoonotic agents further up the food chain. The implications of these findings are discussed in relation to current advice for livestock waste disposal.Food can become contaminated with pathogenic microorganisms at all stages of manufacture and processing (13). However, there is a recognized potential for the on-farm transfer of pathogens to food during primary production (32). Livestock infected with zoonotic agents can excrete pathogens into their feces, and animal wastes have been implicated as a source of infection in a number of cases of human food-borne illness (2, 7). Since livestock wastes are routinely disposed of by spreading to agricultural land used for food production, the practice of waste spreading is an obvious consideration for any integrated pathogen-spread prevention-control strategy (5,17,18).Over the last decade, there has been an increase in the awareness of British farmers on the best practices for storage and disposal of livestock wastes (33). The publication of specific management guidance (26, 27) was driven largely by the need to control chemical pollution from wastes, including nitrate contamination of watercourses and airborne ammonia emissions (35). The effects of these chemical pollutants are immediate and obvious and overshadow more subtle environmental damage such as the dissemination of bacterial pathogens. Evaluation of current guidance, which has been targeted toward the control of chemical pollutants, suggested that it may increase the length of time that pathogens present in the waste could survive in the environment (18). Of particular concern is a move toward immediate solid waste incorporation and band spreading or direct injection of liquid wastes into soil. Such practices are likely to decrease the rate of waste drying, the levels of UV irradiation, and the daily range of temperatures experienced by pathogens present in the waste, potentially extending their survival (6). However, there is currently no experimentally derived information that sup...

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Aims: To determine the fate of Escherichia coli deposited onto grassland via faeces, from naturally colonized cattle, sheep or pigs. Methods and Results: Groups of cattle, sheep and pigs were penned outdoors on grass during November, and removed after 14 days. Escherichia coli populations in the ground declined over 134 days from initial average levels of 5AE34, 4AE31 and 4AE96 log 10 CFU g)1 in cattle, sheep and pig pens, respectively. The maximum Escherichia coli survival time was up to 162 days (190 days taking sampling interval and deposition time into account), but numbers varied significantly amongst the 20 replicates taken each day. Escherichia coli originating from cattle and sheep had average decimal reduction times (D-values) of 38 and 36 days, respectively; E. coli originating from pigs declined significantly faster (average D-value of 26 days).Significance and Impact of the Study: Escherichia coli from livestock faeces can survive on grass for at least 5-6 months, affording opportunity for pathogenic biotypes to contaminate animals, plants or water.