Animal Waste, Water Quality and Human Health

Transport of microbial pollution in catchment systems 163reported in both Europe and Australasia; however, the highest prevalence reportedin North America was only in the range of 50–55%. Most studies of cattle faecesin North America report prevalence rates in the range of 5–10% (n = 7) whilestudies in Europe and Australasia show a broader distribution of prevalence(Figure 5.3). Figure 5.4 shows that it is common for prevalence ofCryptosporidium oocysts in sheep faeces to range between 5–30% in Europeanand North American studies. However all three regions had at least one studythat reported prevalence of >70% in sheep faeces. The higher rates ofprevalence of Cryptosporidium in cattle faeces were predominantly associatedwith juvenile compared to adult animals (Figure 5.5). The majority of studiesshowed that the mean prevalence rate in adult cattle was frequently in therange of 0–10%.Figure 5.3 Mean prevalence rates of Cryptosporidium oocysts in cattle faeces by region.The mean prevalence of Giardia cysts in animal faeces was highest in cat,muskrat, juvenile sheep and juvenile cattle faeces, respectively (see Table 5.3).The mean prevalence of Giardia cysts in animal faeces is also showngraphically in Figure 5.6. Although there were fewer studies investigatingGiardia compared to Cryptosporidium prevalence, it is interesting to note thelow prevalence of Giardia cysts in both adult and juvenile animals (Table 5.3,Figures 5.6 and 5.7).