People are being warned not to eat certain salad products after Listeria was detected.

Seven product lines made by McCormack Family Farms have been recalled by the Food Safety Authority.

The product lines include mixed leaves and spinach, including bags of spinach branded for Tesco, SuperValu and Egan's.

The FSAI is calling on shops to remove affected products from shelves and to put up notices in-store to inform customers.

Prof Paul Whyte, from UCD's School of Veterinary Medicine, said the bacteria can cause both mild and serious illness if eaten in contaminated food.

"Listeria monocytogenes is the actual bacteria, and it can be transmitted to us through contaminated foods.

It can very often manifest as mild, flu-like symptoms to much more severe and life-threatening symptoms where it can actually enter the bloodstream and cause meningitis, attacking our central nervous system."

Last week, more than 200-product lines of ready meals were recalled by the Food Safety Authority after the same Listeria bacteria was detected.

The affected ready meals are made by Ballymaguire Foods and sold by a number of large supermarket chains.

The food safety watchdog urged people to check their fridges and freezers and throw away any affected products.

Details of all the affected ready meal and salad leaves products are listed on the FSAI website.

The FSAI says symptoms of a Listeria monocytogenes infection can include mild flu-like symptoms, or gastrointestinal symptoms such as nausea, vomiting and diarrhoea.

In rare cases, the infection can be more severe, causing serious complications, including in pregnant women, babies, people with weakened immune systems, and the elderly.

The time between initial infection and first symptoms appearing usually takes around three weeks, however, it can range between 3 and 70 days.