Public Health Wales, the Regulatory Service for Cardiff, the Vale and Bridgend Councils, Cardiff and Vale University Health Board and the Food Standards Agency are working together to investigate an outbreak of Campylobacter with links to an unnamed restaurant in Cardiff.
Seven people with confirmed campylobacter infection and two people with suspected infection ate at the restaurant during the weekend of 16 May.
The exact cause of the outbreak remains under investigation, but the restaurant is co-operating fully.
Precautionary control measures at the premises have been implemented to prevent ongoing public health risk.
Campylobacter is usually contracted from eating raw or undercooked meat or from cross-contamination during food preparation.
Most people who are ill recover without requiring treatment, but rarely the infection can cause serious illness.
Dr Gwen Lowe, Consultant in Communicable Disease Control for Public Health Wales, said: “We are investigating those people who were unwell after eating at the restaurant to try to establish the cause of the outbreak, but any ongoing public health risk from this outbreak is very unlikely with the actions already undertaken.”