Table 2.1.

Infectious doses for selected pathogens

Infectious dose	Organisms	Reference
(1)-10–100 viable particles	Norovirus, Rotavirus, EHEC, ETEC, C. difficile, Enterococci incl. VRE	Ward et al. [122], Paton and Paton [88], Pang et al. [85], Lawley et al. [68], Porter et al. [92], Yezli and Otter [130], Robine et al. [97]
≥1 viable particle in water	Oocysts of cryptosporidia	Chappell et al. [17]
>105 viable particles	Salmonella enteritidis	Craven et al. [24]