Newcastle City Council believes that up to 200 cases of sickness have been reported following the city's Street Spice festival held last week.
Four people so far have proved positive for salmonella during initial tests carried out by environmental health officers.
Further results are expected to be available in due course.
12,000 people are believed to have visited the Street Spice festival while it was in Newcastle.
– Stephen Savage Director of Regulatory Services and Public Protection
“The event organisers are cooperating fully and we are continuing to investigate the source of the outbreak.
"Please can anyone with symptoms contact Regulatory Services and Public Protection at the City Council on 0191 278 7878"