Whenever there is an outbreak of food-borne illnesses, Dean Bodager and other members of the Florida Department of Health track down the source. Most outbreaks occur at the point of preparation — a restaurant employee who didn’t wash his or her hands properly, food that wasn’t kept at the correct temperature to prevent bacteria growth, or some sort of cross-contamination.

But sometimes it’s more difficult, such as when health officials learn of people who have fallen ill but did not eat at the same restaurant or buy food from the same market. That’s when the epidemiologists become detectives, interviewing those who have been ill, dissecting their meals and eliminating suspects to find a common thread and, ultimately, the source.

Bodager says the questions investigators ask are carefully tailored to the specific type of infection. Bacteria have different profiles and each takes a specific length of time to cause illness. Hepatitis takes about 30 days, E. coli three to five days, salmonella poisoning one to three, sometimes five, days. Cyclospora can take up to a week and a half. By knowing the type of parasite or bacteria and when the person got ill, investigators know what period of time to look at to determine the point of infection.