What are some symptoms for salmonella poisoning or is it contagious?

I am doing are project to see why some kids on a virtual field trip are sick and are in the hospital for writing class for school.Their symptoms are nausea,vomiting,diarrhea, and abdominal cramps.It might be food poisoning,radiation,or gas fumes.I also think it might be transferred through the boys how held snakes touching the girls.I need to have evidence on how they got it too.I need to have this done by the week of memorial day.Please help me!