Animal Waste, Water Quality and Human Health

90Animal Waste, Water Quality and Human Healthnorthern hemispheres. However, in contrast to the single seasonal summer peaksobserved for Salmonella and E. coli O157:H7 infections, there are two warmseason peaks with Campylobacter, one in the late spring-early summer andanother in the late summer-early fall (Stanley et al. 1998). Young children (0 to4 years of age) living in close proximity to high densities of livestock are at agreater risk of Campylobacter infection than their urban-dwelling counterparts(Green et al. 2006), further suggesting that environmental exposure may play a role.While waterborne outbreaks of campylobacteriosis are less common than thoseassociated with the protozoal parasites, Crypto. parvum and G. duodenalis, and E.coli O157:H7, they do occur. Outbreaks of campylobacteriosis are typicallyassociated with un-chlorinated drinking water (Hrudey & Hrudey 2007; Said et al.2003). A large outbreak of waterborne disease in Walkerton, Ontario, Canadaresulting in seven deaths and over 2300 cases of gastrointestinal illness wasassociated with infections by both E. coli O157:H7 and Campy. jejuni (Auld et al.2004; Garg et al. 2006). In this outbreak, intense rainfall is thought to havewashed excreta from a dairy farm into a well which supplied water to the town.This contamination event coupled with a failure in the water chlorination system isthought to have caused the outbreak. Similar but smaller drinking-waterassociatedoutbreaks have been reported in Norway, Finland and Sweden(Jakopanec et al. 2008, Schönberg-Norio et al. 2004). Finally, campylobacteriosishas also been associated with recreational use of water (Kärenlami et al. 2007,Schönberg-Norio et al. 2004).3.3.2.1 Faecal shedding of Campylobacter by livestockand wildlifeCampylobacters are frequently shed in the faeces of livestock, poultry, wildmammals and wild birds (Stanley & Jones 2003, Skelly & Weinstein 2003,Humphrey et al. 2007). In addition, to domestic animals, Campylobacter spp.has been isolated from the faeces of a variety of wildlife species including butnot limited to crows, common gulls, pigeons, puffins, ducks, Canada geese,Sandhill cranes, wild rabbits, rats, starlings, and sparrows (reviewed in Skelly &Weinstein 2003, Kwan et al. 2008). Companion animals such as dogs also canshed different species of Campylobacter (Hald et al. 2004) and are a risk factorfor human infection. In a recent study in Scotland, it was reported thatprevalence rates of Campylobacter ranged from 1.3% for dogs to 41.4% forpoultry (Ogden et al. 2009). In this study, prevalence of Campylobacter in thefaeces of cattle, sheep and pigs was very similar (ranging from 21.9% to 26.7%)as it was among ducks, geese, gulls, pigeons and wild birds of unknown origin(ranging from 23.7% to 27.8%). The average Campylobacter CFU/g of faeces