Final answer:
The question seems to misinterpret the context, which describes a scenario of food poisoning at a microbiology department's picnic, not a closure of any branch. Symptoms like nausea, vomiting, diarrhea, and one case of shock suggest food poisoning, with the chicken salad being the likely culprit. An investigation would follow to identify the cause.
Step-by-step explanation:
The branch being shut down at the company picnic is not explicitly mentioned in the provided context. However, based on the details given, it appears you're asking about a scenario involving a microbiology department's end-of-year picnic, consequent illness among participants, and food safety. In this context, there may be confusion as this seems to refer to a department at a school rather than a company branch. The microbiology department itself is not being shut down; rather, individuals from this department have experienced food poisoning, possibly linked to the chicken salad.
Food poisoning symptoms like nausea, vomiting, and abdominal cramping affected almost the entire group, except for two vegetarian students who did not consume the chicken salad, implying that the source of the illness could be the chicken salad. It highlights the importance of food safety and proper hygiene practices, as well as thorough cooking and storage of food. An investigation involving the collection of blood and stool samples, as well as an analysis of the food served, would be essential to identify the specific pathogen responsible for the outbreak and to implement measures to prevent such incidences in the future.