A leading public health lawyer has called for a thorough investigation to establish the cause of a salmonella outbreak affecting at least 23 victims.
Amandeep Dhillon said the "unusual" outbreak, which has left eight people in a stable condition at Birmingham's Heartlands Hospital, might provide lessons to help prevent future outbreaks.
The Heart of England NHS Foundation Trust has confirmed that four of its staff and 19 patients have tested positive for a common strain of salmonella.
Restrictions have been put in place on visitors to eight wards at the hospital, and deep-cleaning processes have been put in place.
Hospital officials have also organised "stringent" testing of food and water at Heartlands, which did not highlight any sign of salmonella bacteria.
Health officials have described the rise in salmonella cases in the Birmingham outbreak as "unusual" and believe there might have been more victims who did not need hospital treatment.
Mr Dhillon, of Birmingham-based law firm Irwin Mitchell, said: "Salmonella is a very serious illness and some victims can go on to develop long-term health problems from which they never fully recover. Because of this, it is vital that the problems at Heartlands Hospital are thoroughly investigated.
"Clearly the priorities must be to treat all of those who have been made ill and to take immediate and effective steps to prevent other patients, visitors and staff becoming ill.
"Attention will then need to turn to identifying the cause of the infection. This will be essential to provide victims and their loved ones with the answers they will want as to what caused their illness.
"There may also be important lessons to be learnt to reduce the risk of future outbreaks of serious illness."
Mr Dhillon is representing more than 40 victims following an outbreak of salmonella at a spice festival in Newcastle in February and March last year.
An investigation by Public Health England and Newcastle City Council, published in June last year, concluded that the use of uncooked curry leaves, contaminated with several different bacteria, was the cause of the earlier outbreak.