Which is an example of laboratory evidence in an outbreak investigation?

• A. The germ that caused illness is found in a food item collected from a sick person's home, a retail location, or from the production environment
• B. Same DNA fingerprint linking germs found in foods or production environments to germs found in sick people
• C. Both A and B
• D. Interviews with sick people

Answer: (C)

Laboratory evidence in an outbreak investigation includes confirming the pathogen in suspected sources and showing a genetic link between the source and patient cases. Finding the germ in a food item or in the production environment provides direct confirmation that the source is contaminated. Using DNA fingerprinting or molecular typing to show that the same strain found in foods or the production setting matches the strains found in sick people strengthens the connection between exposure and illness. Together, these lab findings establish a solid link from source to illness and guide control measures. Interviews with sick people are epidemiologic evidence, not laboratory evidence, so they don’t demonstrate the same direct lab connection.