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Causative Agents

Determining the causative agent is critical in a foodborne disease outbreak investigation and is used to link cases together to identify an outbreak, exclude unrelated illnesses, link cases with a food vehicle, and determine the most effective control measures. 

Laboratory testing is the best way to determine the causative agent. However, laboratory testing takes time and is not always possible. While waiting for laboratory results, clinical findings and foods eaten by cases can provide insights into the causative agent. Additionally, testing for different causative agents requires specific specimens and procedures, so clues to the likely causative agent are critical. 

Clinical Indications

Signs and SymptomsIncubation PeriodDuration of Illness
Vomiting, diarrhea (rarely bloody), abdominal pain, fever Less than a day to 4 days 2-5 days
Vomiting, diarrhea (sometimes bloody), abdominal pain, fever Less than a day to a week Several days to a week
Abdominal pain, diarrhea 1-4 weeks Several weeks

Food Vehicles

Photos of eggs

Raw eggs are associated with Salmonella

Photo of cheese and crackers

Unpasteurized soft cheeses are associated with Listeria, Salmonella, STEC, and Campylobacter

Photo of seafood

Mussels, clams, and scallops are associated with saxitoxin

Photo of raw chicken meat

Undercooked meat or poultry is associated with Salmonella, Campylobacter, and Clostridium perfringens

Photo of mushrooms

Wild mushrooms are associated with mushroom poisoning

Photo of jam jars

Homemade canned goods are associated with Clostridium botulinum 

Which of the following pathogens would generally have the longest incubation period?

Click the correct pathogen below.

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Types and Collection of Specimens