Animal Waste, Water Quality and Human Health

44Animal Waste, Water Quality and Human HealthBetween 1971 and 2006, Salmonella was identified in the USA as the onlypathogen in 20 outbreaks associated with drinking-water which represented 3,588cases; seven deaths were attributable to Salmonella serovar Typhimuriumoutbreaks (Craun et al. 2010). Interestingly, only five of the outbreaks wereassociated with the human-restricted pathogen Salmonella serovar Typhi. InCanada, between 1974 and 2001 Salmonella was associated with 16 waterbornedisease outbreaks. In Australia, Salmonella was associated with fivedrinking-water associated outbreaks between 2001–2007 (Dale et al. 2010).Campylobacter spp RANK 2 Campy. spp. are the most common cause ofbacterial gastroenteritis worldwide (Friedman et al. 2004, Silva et al. 2011). Thegenus Campylobacter is comprised of approximately 21 species and eightsubspecies (Debruyne et al. 2010). At least twelve of these species are associatedwith human illness; however, the vast majority of infections (80–90%) areassociated with Campy. jejuni. Campy. coli is the second most common speciesassociated with campylobacteriosis and other species such as Campy. upsaliensisand Campy. lari are occasionally associated with gastrointestinal illness inhumans (Friedman et al. 2004, Humphrey et al. 2007).Subspecies of Campy. fetus have long been recognized as a cause of abortionand infertility in sheep and cattle (Silva et al. 2011); however, the role ofCampy. jejuni in gastroenteritis in humans was only established in the 1970safter selective cultural techniques were devised to isolate the organism fromstools (Engberg et al. 2000). The organism is a small spiral-shapedGram-negative bacterium which possesses a single flagellum. Its small size hasbeen exploited in selective isolation of the organism in the laboratory. Passageof liquid samples through a 0.45 µm filter excludes most other bacteria andallows isolation of the campylobacters on solid media. The genome of theorganism is also small (1.6–1.7 Mb) and has a low GC content (Lefébure et al.2010; Biggs et al. 2011). Further, the organism metabolizes few carbohydratesubstrates and most strains are microaerophilic and cannot grow in anatmosphere with more than 10% oxygen. Most strains grow best at atemperature of 42°C and are highly susceptible to desiccation. Resistance to thefluoroquinolone antibiotics is very common among Campy. jejuni isolates and isthought at least in part to be related to their use for growth promotion in animalfeeds (Cody et al. 2010, Smith & Fratamico 2010).Campylobacteriosis is usually a self-limiting gastroenteritis with symptomsranging from loose stools to profuse watery diarrhoea and occasionally stoolsthat contain blood, mucus or pus (Kirkpatrick & Tribble 2011). However, incertain individuals such as the very young and immuno-compromised adults, amore persistent diarrhoea with prolonged excretion of the organism may ensueand there is greater chance of the infection recurring following subsequent