A listeriosis outbreak linked to caramel apples has been reported in a number of states and at least four deaths have been linked to the prepackaged food item.

ABC reported that the Center for Disease Control and Prevention (CDC) reported that at least 28 people from 10 states were infected with Listeriosis due to Listeria monocytogenes, a bacteria that can cause life-threatening illness.

Of those infected, five died, four of whom reportedly died of Listeriosis.

Infection is usually caused when a person ingests listeria monocytogenes bacteria, and symptoms include gastrointestinal distress, fever and muscle aches. It is particularly harmful for the elderly, pregnant women or anyone with a weak immune system.

More severe cases include swelling of the brain, or inflammation of the membrane surrounding the brain and spinal cord.

Minnesota, Arizona and Texas are some of the states where the infected patients were reported, ABC reported.

In order to alert consumers until an investigation is complete, the CDC has warned consumers to avoid eating prepackaged caramel apples.

The investigation is ongoing in cooperation with the U.S. Food and Drug Administration and state health organizations where the infections were reported.

The age range of those affected includes both adult and children, but three of the 28 affected were between the ages of 5 and 15, ABC reported.

Dr. William Schaffner, an infectious disease expert from the Vanderbilt University School of Medicine, told ABC Listeriosis can have a long incubation period from three to 70 days.

"We can anticipate that more illnesses will occur over time," Schaffner said. "Even [if] the product is removed from the market a lot of these [caramel] apples have been consumed."

Another problem is that the bacteria can grow well even in refrigerator temperatures.

And since caramel apples have a long shelf life, the apples being eaten now are likely left over from the fall. The CDC said the caramel apples can have a shelf life of longer than one month.