UK health experts believe sun-dried tomatoes could be the cause of a recent outbreak of hepatitis A.
The Health Protection Agency and the Food Standards Agency fear contaminated samples were to blame for the infection that hospitalised four people and caused illness in another three people in late 2011.
Hepatitis A virus is carried by human faeces and can be passed on through contact with food or water.
Severe cases can lead to liver failure.
All of the seven people infected have since made a recovery.
One of the strains of hepatitis A identified in two of the patients was identical to a strain that caused a similar outbreak linked with sun-dried tomatoes in the Netherlands in 2010, saysa report.
Four of the patients in this latest outbreak in England said they had consumed sun-dried tomatoes.
Officials are on the alert for further cases. But they say they do not know which brands of sun-dried tomatoes might be involved. This is because there is no reliable test to find the virus in food.
A spokeswoman for the Food Standards Agency said: "Sun-dried tomatoes are being investigated as one possible source of the hepatitis A cases reported last year.
"However, no food source has been conclusively identified so far and no other relevant cases have been reported in the UK since November 2011. The investigation by FSA and HPA is ongoing."
Hepatitis A is a notifiable condition. This means that when the condition is diagnosed, the doctor making the diagnosis must inform the local authority.
In most cases the infection is relatively short-lived and people recover within a couple of months.