Parents are being warned to keep their children away from Sutton Park as an eighth child has become infected with e.coli.
The Health protection Agency (HPA) is advising parents to keep children aged below 10-years-old away from Sutton Park until further notice.
The latest child to contract E. coli O157 was admitted to hospital but has now been released and is expected to make a full recovery.
The HPA is working with Birmingham City Council to investigate the outbreak at Sutton Park in Sutton Coldfield.
The HPA said the strain of the bacteria was often associated with contact with rural environments that may have been contaminated by animal faeces.
The advice being given is to wash your hands, especially after contact with animals, after going to the toilet and immediately before eating.
Cyclists and walkers are also being advised to wash their tyres, footwear and hands after visiting Sutton Park as an extra precaution.
However authorities say despite previous warnings people are still allowing children to play in areas of the park where there is animal faeces.
Birmingham City Council’s Head of Parks, Darren Share said:
Sutton Park, covers around 2,400 acres and is thought to attract around two million visitors annually.
Designated a National Nature Reserve, the former royal deer park is included in English Heritage's list of historic parks and gardens, and includes sites of archaeological interest.