Clinical presentation	Potential food-related agents to consider
Gastroenteritis (vomiting as primary symptom; fever or diarrhea also may be present	Viral gastroenteritis, most commonly rotavirus in an infant or norovirus and other caliciviruses in an older child or adult; or food poisoning caused by preformed toxins (e.g., vomitoxin, Staphylococcus aureus toxin, Bacillus cereus toxin) and heavy metals
Noninflammatory diarrhea (acute watery diarrhea without fever or dysentery; some patients may presentwith fever)*	Can be caused by virtually all enteric pathogens (bacterial, viral, parasitic) but is a classic symptom of enterotoxigenic Escherichia coli, Giardia, Vibrio cholerae, enteric viruses (astroviruses, noroviruses, and other calciviruses, enteric adenovirus, rotavirus), Cryptosporidium, Cyclospora cayetanensis
Inflammatory diarrhea (invasive gastroenteritis; grossly bloody stool and fever may be present)†	Shigella species, Campylobacter species, Salmonella species, enteroinvasive E. coli, enterohemorrhagic E. coli, E. coli O157:H7, Vibrio parahaemolyticus, Yersinia enterocolitica, Entamoeba histolytica
Persistent diarrhea (lasting at least 14 days)	Prolonged illness should prompt examination for parasites, particularly in travelers to mountainous or other areas where untreated water is consumed. Consider Cyclospora cayetanensis, Cryptosporidium, Entamoeba histolytica, and Giardia lamblia.
Neurologic manifestations (e.g., paresthesias, respiratory depression, bronchospasm, cranial nerve palsies)	Botulism (Clostridium botulinum toxin), organophosphate pesticides, thallium poisoning, scombroid fish poisoning (histamine, saurian), ciguatera fish poisoning (ciguatoxin), tetraodon fish poisoning (tetraodontoxin), neurotoxic shellfish poisoning (brevetoxin), paralytic shellfish poisoning (saxitoxin), amnesic shellfish poisoning (domoic acid), mushroom poisoning, Guillain-Barré syndrome (associated with infectious diarrhea caused by Campylobacter jejuni)
Systemic illness (e.g., fever, weakness, arthritis, jaundice)	Listeria monocytogenes, Brucella species, Trichinella spiralis, Toxoplasma gondii, Vibrio vulnificus, hepatitis A and E viruses, Salmonella typhi and Salmonella paratyphi, amebic liver abscess