BBC reports that Salmonella Typhimurium DT193 illnesses are on the rise and no one is really sure whether they are linked or what the source might be.

Health officials are investigating how to stop a rise in cases of a salmonella strain which can leave patients severely ill, the BBC has learned. Cases of Salmonella Typhimurium DT193, rose 630% from 71 in 2004 to 518 in 2011 in England and Wales, said the Health Protection Agency. A Devon man diagnosed with DT193 poisoning in 2011 spent five days in hospital and is still suffering.

DT193 cases rose in the South West from 14 in 2004 to 73 in 2011. DT193, which is most common in beef and pork, is also found in unpasteurised milk, desserts and sandwiches according to the HPA.

It said in a statement: "The HPA study, which is ongoing, involves people who were ill being questioned about what they ate and activities they were involved in prior to becoming unwell.
"The aims of the study are to find any links between those who were unwell and give insights as to how to stop the increase in cases."

Devon builder Ian Mason, 54, was among eight people who contracted DT193 after attending a hog roast, identified by the HPA as a possible cause of the outbreak, in April 2011.

S. Typhimurium DT193 was linked to a bunch of European outbreaks in the 80s and 90s. Two of the big outbreaks were linked to pork products (in the UK and Italy).