Animal Waste, Water Quality and Human Health

334Animal Waste, Water Quality and Human Healthcomplicate interpretation from the regulatory standpoint, which focuses on FIOdensity-based classification. And while a recent field study reported a lowcorrelation between quantitative Bacteroidales markers and FIOs, there was agood correlation between indicator and Bacteroidales delivery flux (Stapletonet al. 2009). Other studies report a good correlation between FIOs andBacteroidales markers directly (Shanks et al. 2006). These differences are likelyto be caused by some combination of differential survival between host-specificmarkers and FIOs, low/varied levels of faecal contamination, or geographicvariation in the prevalence of markers.Since the purpose of recreational water quality regulation is primarily to protecthuman health, the extent to which host-specific markers are able to predict theoccurrence of human pathogens may be of greater importance than theircorrelation to FIOs ((Field & Samadpour 2007). A study in Alberta, Canada,compared the occurrence of human, ruminant and pig-specific Bacteroidalesmarkers with the pathogens (Campylobacter, Salmonella, and E. coli O157:H7)and found a positive relationship between a Bacteroidales general markerand pathogens (Walters & Field 2006). The detection of ruminant-specificBacteroidales markers also predicted E. coli O157:H7 occurrence and there wasa significant increase in the probability of detecting Salmonella when ruminantmarkers were also present. Another Canadian study which compared theoccurrence of human-, ruminant- and porcine-specific Bacteroidales markers inwater samples to the occurrence of FIOs, thermotolerant Campylobacter,Salmonella, and shigatoxin genes yielded similar results (Fremaux et al. 2009),with elevated E. coli counts related to the presence of human andruminant markers. Furthermore, ruminant marker CF128 was predictive ofthe presence of Salmonella spp (Fremaux et al. 2009). In addition toBacteroidales, some studies have reported good predictive value betweencoliphages and the presence of human viruses (Ogorzaly et al. 2009) andbetween FIOs, coliphages, and enteroviruses (Costan-Longares et al. 2008).Neither Bacteroidales nor coliphages as a single indicator proved suitable forpredicting Cryptosporidium oocysts through the wastewater treatment chain(Costan-Longares et al. 2008).It has been suggested that a combination of bacterial and phage indicators isnecessary to ensure the microbial quality of reclaimed water (Costan-Longareset al. 2008). In a New York river system study (examining microbial fate,transport and partitioning) Cryptosporidium and Giardia demonstrated a greaterassociation to particulate matter than FIOs, although settling rates were similar(Cizek et al. 2008). The correlation between these organisms and FIO was,however, weak in this study as well as in others (Savichtcheva & Okabe 2006,Field & Samadpour 2007, Cizek et al. 2008). Faecal indicators organisms, such