Investigates how the illness is being transmitted
This is what the Health Unit concentrates on, since the doctor treating the hospitalized children has already sent samples to a lab with a request to identify the pathogen.
The most likely suspect is one of the many different strains of E. coli. Many people are falling ill, so the bacterium probably has contaminated something that many residents are consuming - it isn't just a matter of poor hygiene in one household's kitchen.
What do you examine first?