The risk of disease transmission to livestock posed by contamination of farm stored feed by wildlife excreta

Abstract

Livestock feed is susceptible to contamination from wildlife excreta during on farm storage. Pathogens associated with diseases such as paratuberculosis, salmonella and cryptosporidiosis are present in wild rodent and bird excreta. Feed stores on four farms in the east of Scotland were monitored monthly over the winter of 1998/9 to quantify the levels of wildlife faecal contamination. A mean of 79·9 rodent (95% confidence interval: 37·5–165·9) and 24·9 (14·3–41·7) bird faeces were deposited per m2 of stored feed per month. It was estimated that individual cattle and sheep could encounter 1626 and 814 wildlife faeces over the winter.A model based on the numbers of infected faeces consumed per annum was used to estimate ‘infectious probabilities’ (Pinf) required to account for the reported prevalence of paratuberculosis, salmonella and cryptosporidiosis in sheep and cattle in the east of Scotland in 1998. Based on empirical data for input variables [the number of faeces encountered (Fe), the number ingested (Fi) and the prevalence of infection in wildlife species (Ip)], Pinf estimates ranged from 1·6×10−8 for cryptosporidiosis in sheep to 8·2×10−6 for paratuberculosis in cattle. The model suggested that ingestion of feed contaminated by wildlife faeces could account for the prevalence of all three diseases. Wildlife faecal contamination of stored feed should be given serious consideration as a potential source of infection to livestock.

The Role of Contaminated Feed in the Epidemiology and Control ofSalmonella entericain Pork Production

“…Noting that sampling protocols differed among countries, and differences among countries other than Germany were not statistically significant, this large study suggests considerable risk of post-processing recontamination of animal feed in at least some of these countries. Potential points of recontamination include post-decontamination processing and handling at feed mills (Davies and Wray, 1997;Jones and Richardson, 2004), during transport (FedorkaCray et al, 1997), or contamination during storage and delivery on farms (Daniels et al, 2003).…”

“…The magnitude of the task of excluding Salmonella from farms, including feed storage facilities, is demonstrated by recent observations on Scottish farms. Approximately 80 rodent and 25 bird feces were deposited per m 2 of stored feed per month over the winter period (Daniels et al, 2003). Given the potential for wild birds, pets, rodents and insects in the farm environment to be infected with Salmonella (Barber et al, 2002;Craven et al, 2000;Davies and Breslin, 2003a,b), it is evident that any Salmonella-free standard enforced in commercial feed production is at considerable risk of being negated by downstream recontamination before the feed is offered to animals.…”

Sheep management and cryptosporidiosis in central Mexico

“…Forage is usually stored in farms as means of providing feeding to sheep and is also used as bed in farms all year long. It is usually kept outside the facilities or in locations where it could be exposed to flies or wildlife that could contaminate it becoming a potential risk when used as food or bed (Daniels et al 2003;Szostakowska et al 2004).…”

User behaviour, best practice and the risks of non-target exposure associated with anticoagulant rodenticide use

“…Commensal rodents contaminate and consume crops (Daniels et al, 2003;Stenseth et al, 2003), damage property through gnawing wires and cables (Leung and Clark, 2005) and act as vectors of human and animal diseases such as leptospirosis, trichinosis and salmonellosis (Daniels et al, 2003;Meerburg et al, 2009;Webster and Macdonald, 1995). The control of rodent populations is therefore common and widespread.…”