Animal Waste, Water Quality and Human Health

300Animal Waste, Water Quality and Human Healthexclusion of animals from the aquatic environment, an option difficult to achievewith avian species but likely successful for ruminants. Signage designatingimpacted water bodies as unsuitable for swimming would aid the reduction ofexposure through recreational contact. Enhanced public education can inducebetter sanitation practices: safe handling of live poultry and livestock, safehandling of carcasses (food chain model), and adequate management of thedrinking-water supply. The results of the New Zealand Campylobactertransmission route (CTR) study (Baker et al. 2002) identified several potentialrisk management options for residents of, or visitors to, rural communities.Among these were public awareness about the presence of Campylobacter inruminant faeces, the need for adequate hand-washing after animal handling andprior to “hand-to-mouth” activities, and other intervention messages such asavoided consumption of untreated water (such as roof-collected water due theprevalence of Campylobacter in avian species). Adequate treatment is alsonecessary for public drinking-water supplies derived from surface waters inagricultural areas. Several instances of waterborne disease outbreaks have beenattributed to insufficient, untimely or inadequate treatment of potable watersupplies (Stehr-Green et al. 1991, Inkson 2002, and O’Connor 2002).8.4.5 E. coli O157:H7The Canadian Walkerton Inquiry highlights the dangers of waterbornetransmission of pathogens such as E. coli O157:H7. Significant morbidity andseven fatalities occurred when Walkerton’s municipal water supply becamecontaminated with Campylobacter and E. coli O157:H7. It was presumed thatthe contamination arose from farm animal run-off into a shallow well, fromwhich the water supply was taken (O’Connor, 2002). In 1996, an outbreak of E.coli O157 infection in central Scotland resulted in over 500 confirmed cases and17 deaths (Cowden et al. 2001). Scotland continues to report higher incidencerates of infection with verotoxin-producing Escherichia coli (VTEC), such as E.coli O157:H7, than elsewhere in the United Kingdom (Figure 8.1). In addition topotable water supplies, disease outbreaks have also been associated withconsumption of vegetables irrigated with contaminated water (Islam et al. 2004;CDC 2006, online: http://www.cdc.gov/foodborne/ecolispinach/100606.htm,Jay et al. 2007) and at recreational waters (Levy et al. 1998, Proctor & Davis2000, Samadpour et al. 2002, Keene et al. 2004, CDC 2008).Characteristics of E. coli O157:H7 such as the ability to enter a viable butnon-culturable state and to survive under conditions of low pH and temperaturelend to its ease of transmission (Pond 2005, Nwachuku & Gerba 2008). Multiplemediation measures are required which should address load interventions