Listeria outbreak has been deadly for dozens of people in various states. At least four people have died after they ate caramel apples, which, in turn, are believed to may have been infected with Listeria Monocytogenes.

Five people have actually been tested for the Listeria outbreak, but the fifth case's test results are still pending.

Some 28 people have been infected with this particular deadly bacterium in 10 different states in the US, according to the Centers for Disease Control and Prevention. Nine of those who were reportedly sick with the Listeria outbreak were pregnant.

Based on the statistics, pregnant women are 10 times more likely to get Listeriosis after eating food that has been contaminated. Of the rest of the cases, however, three of them were children who were otherwise healthy.

Symptoms of the Listeria outbreak include headache, confusion, muscle aches, loss of balance, stiff neck, convulsions, and fever. Typically, the symptoms start to manifest three to 70 days after ingesting the contaminated food.

To date, 15 of the 18 people who were interviewed about their illnesses remembered that they ate pre-packaged caramel apples that were commercially produced before they started to get sick. Majority of those who got sick with consulted with their physician in late October and November.

As of now, the investigators who are looking into this recent Listeria outbreak are still trying to figure out which specific brands of the contaminated caramel apples might be involved. They are also working very hard to determine the source of the infected apples.

For the meantime, until the CDC gets to the bottom of the Listeria outbreak, the center is warning consumers who may have purchased pre-packaged caramel apples with toppings, such as sprinkles, chocolate, or nuts, not to eat them.

There have been nearly 1,600 cases of the Listeria outbreak that have been reported all over the United States every year. According to the CDC, this disease kills almost 260 people annually.