Three hospital patients who were part of a salmonella outbreak in Birmingham have died, according to health officials.
But the death certificates of two patients did not mention the bacteria as a contributing factor, while the coroner's report on the third patient has not yet been delivered, said Dr Mamoona Tahir, consultant in health protection for PHE West Midlands.
The confirmation of the deaths came after Public Health England (PHE) said it had launched an investigation into a national salmonella outbreak which affected 156 people, mainly in Hampshire.
Across England, experts are examining 55 cases in Hampshire, 32 of which have been connected with a restaurant, and 33 cases in Cheshire and Merseyside, 31 of which have been linked to one takeaway.
PHE are also looking at 43 cases in the West Midlands, 34 of which were connected with the Birmingham Heartlands Hospital outbreak, as well 25 cases in London.
The source for the West Midlands outbreak has not yet been identified, although investigations are ongoing and officials are working as part of the national outbreak control team, PHE said.
The cases occurred in “isolated clusters” over several months but officials now fear they could be potentially linked.
PHE investigators will work with Food Standards Agency to understand the cause of the outbreak - which may have also affected people in France and Austria.
Dr Paul Cleary, a consultant epidemiologist leading the PHE investigation, said they are working with colleagues across PHE, at the Food Standards Agency, in local authorities and with other public health organisations in Europe to investigate the cause of this outbreak.
He said they are making “good progress and hope to have more conclusive evidence shortly”.
Dr Cleary added: “We will continue to monitor the situation and if there is any further public health action necessary then we will ensure that this takes place.”
Salmonella Enteritidis is a strain of bacteria that causes gastrointestinal illness and is often linked to poultry or eggs.
Dr Tahir added: “Salmonella is transmitted by ingesting the bacteria, either from not washing hands thoroughly or eating infected food such as meat, eggs, poultry and milk.
"Other foods like green vegetables, fruit and shellfish can become contaminated through contact with manure in the soil or sewage in the water.
"Symptoms include diarrhoea, stomach cramps and sometimes vomiting and fever.
"Most people recover without treatment, but if you become seriously ill you may need hospital care because the dehydration (fluid loss) caused by the illness can be life-threatening.
"People already in hospital are therefore more vulnerable, due to their reduced immunity, which is why we always advise people with sickness and diarrhoea bugs not to visit patients in hospital until they have been clear of symptoms for at least 48 hours."
Additional reporting by PA