E coli, noroviruses, rotavirus, Salmonella species,Campylobacter jejuni, Shigella species, Aeromonas species, Plesiomonas shigelloides, enterotoxigenic Bacteroides fragilis and Vibrio species, the parasites Giardia duodenalis, Cryptosporidium species, Entamoeba histolytica, and Microsporidium