Animal Waste, Water Quality and Human Health

Zoonotic waterborne pathogen loads in livestock 75but it involves many people: 600–700 million poor people keep livestock (IFAD2004). In these systems, livestock are also a major source of power with morethan 50% of arable land cultivated by draught animals (Ramaswamy 1994). Inhigh-intensity systems, dense concentrations of industrial livestock productioncreate vast quantities of manure and concentrated environmental problems. Thesituation in developing countries is compounded by ineffective environmentalregulations and the location of agro-industry in or close to cities. Inlow-intensity systems, livestock faeces is an important commodity used forfertilizer, fuel, animal feed and building material. Excessive environmental loadsmay not be a problem but there are much greater human exposure risks fromlivestock faeces and hence a greater potential for zoonoses.Table 3.1Global total of various livestock species.2000 2012 % changeCattle 1,314,813,626 1,428,636,207 8.7Buffaloes 164,114,418 194,168,699 18.3Sheep 1,059,759,106 1,078,948,201 1.8Goats 751,440,392 921,431,865 22.6Pigs 898,813,265 965,855,414 7.5Horses 57,223,059 58,459,080 2.2Asses 41,631,889 42,152,395 1.3Chicken 14,401,862,000 19,458,571,000 35.1Turkeys 457,993 449,442 −1.9Duck 947,569,000 1,187,674,000 25.3Data source: http://faostat.fao.orgSource: Food and Agriculture Organization of the United Nations 1996.3.1.3 Pathogen loading by livestock and recreationalwaterborne zoonotic diseaseThere is growing concern among public health agencies from both developed anddeveloping countries that zoonotic pathogens in livestock excreta pose anunacceptable waterborne public health risk (Cotruvo 2004). This concern isbased on the large numbers of livestock kept (Table 3.1), the prevalence ofwater-borne zoonoses among livestock, outbreak investigations linkingwaterborne zoonotic illness in humans to livestock (e.g., Auld, McIver &Klaassen 2004), inferences drawn from case-control studies (Hunter &Thompson 2005), and direct human infectivity trials (DuPont et al. 1995,Okhuysen et al. 1999). Taken together, this growing body of evidence suggests