The Ontario Ministry of Health says four people have been sickened after consuming beef tongue believed to be contaminated with Listeria. The Canadian Food Inspection Agency is recalling many brands of jellied beef tongue sold in various Ontario stores. Many of the products were served to customers by store clerks and others were pre-packaged.

The food inspection agency says it's conducting an investigation that may lead to more products being recalled. It says people should check to see if they have the recalled beef tongue and either throw it out or return it to the store. Beef tongue products recalled due to Listeria risk The agency says food contaminated with Listeria may not look or smell spoiled but can still make people sick.

Symptoms of listeriosis — the illness caused by the Listeria bacteria — can include vomiting, fever, muscle aches, severe headache and a stiff neck, the recall notice said. People who are elderly or have weakened immune systems are especially at risk for becoming seriously ill. Pregnant women are also at risk because even though they may only have mild flu-like symptoms, listeriosis can lead to premature delivery, infect the newborn and possibly cause stillbirth.

The bacterium Listeria monocytogenes, widely known as Listeria, can cause serious illness, particularly for pregnant women, older adults and individuals with weakened immune systems. (Kateryna Kon/Shutterstock) Listeriosis can be fatal in severe cases, the recall notice said. As of Mo.