At a recent presentation, Dr. Alan Melnick, a public health officer in both Oregon and Washington, provided a useful list of alternative causes of symptoms to consider when someone claims a food-borne illness. Other causes of symptoms that might be confused for food-borne illness include (but may not be limited to):

Another practical piece of advice offered by Dr. Melnick: When assessing a food-borne illness claim, determine whether the incubation period is compatible with the illness. Incubation periods (along with other useful information) were provided by Dr. Melnick (relying upon the CDC) as follows:

Pathogen

Incubation

Symptoms

Duration

Source

Bacillus cereus

1-6 hours (vomiting); 6-24 hours (diarrhea)

Nausea and vomiting or colic and diarrhea 24 hours (short form); 24-48 hours (long form) Soil organism found in raw, dry and processed foods, e.d. rice
Campylobacter 2-10 days; usually 2-5 days Diarrhea, cramps, fever and vomiting; diarrhea may be bloody 2-10 days Raw and undercooked poultry, unpasteurized milk, water
Clostridium botulinum (botulism) 2 hours to 8 days; usually 12-48 hours Vomiting, diarrhea, blurred vision, double vision, difficulty swallowing, descending muscle weakness Variable (days to months) Home-canned food, improperly canned commercial foods
Clostridium perfringens 6-24 hours Cramps, diarrhea 24-48 hours Meats, poultry, gravy; foods kept warm
Enterro-hemorrhagic E. coli, including E. coli O157:H7 and other Shiga toxin-producing E. coli (STEC) 1-10 days; usually 3-4 days Diarrhea, frequently bloody; abdominal cramps (often severe); little or no fever; 5-10% develop Hemolytic-uremic syndrome (HUS) and average of 7 days after onset, when diarrhea is improving (more common in children, elderly and immune-compromised) 5-10 days Ground beef, unpasteurized milk and juice, raw fruits and vegetables, contaminated water, sprouts, person to person
Listeria 9-48 hours for GI symptoms; 2-6 weeks for invasive disease Fever, muscle aches and nausea or diarrhea; pregnant women may have flu-like illness and stillbirth; elderly, immune-compromised and infants infected from mother can get sepsis and meningitis Variable Fresh soft cheeses, unpasteurized or inadequately pasteurized milk, ready-to eat deli meats and hot dogs
Salmonella 6 hours to 10 days; usually 5-48 hours Nausea, diarrhea, cramps, fever 4-7 days Poultry, eggs, meat, unpasteurized milk or juice, raw fruits and vegetables (e.g., sprouts), person to person
Shigella 12 hours to 6 days; usually 2-4 days Abdominal cramps, fever and diarrhea; stool may contain blood and mucus 4-7 days Contaminated food or water, raw foods touched by food workers, raw vegetables, egg salads, person to person
Staph (toxin) 30 minutes to 8 hours; usually 2-4 hours Nausea, cramps, vomiting, diarrhea  24-48 hours Custards, cream fillings, potato or egg salad, sliced meats
Vibrio cholerae 1-5 days Profuse watery diarrhea and vomiting, severe dehydration 3-7 days Contaminated water and shellfish, street vended food 
Vibrio parahaemolyticus 4-30 hours Watery diarrhea, abdominal cramps, nausea, vomiting  2-5 days Undercooked or raw seafood (fish and shellfish) 
Vibrio vulnificus 1-7 days Vomiting, diarrhea, abdominal pain; more severe in patients with liver disease or who are immune-compromised; can cause invasive infection (sepsis) 2-8 days Raw seafood, particularly oysters, harvested from warm coastal waters 
Yersinia 1-10 days; usually 4-6 days Appendicitis-like symptoms (diarrhea and vomiting, abdominal pain)  1-3 weeks  Undercooked pork, unpasteurized milk, contaminated water