Listeriosis is a food poisoning condition that occurs when one eats foods that contain Listeria monocytogenes bacterium. Listeria is common in the elderly, adults with weak immune systems, expectant women and newborn babies. Healthy adults and children can have Listeria monocytogenes without suffering any serious illness. Newborns can have listeria if their mothers eat contaminated food in their pregnancy term.

Where Does Listeria Come From?

Listeria monocytogenes is found in water, soil, and animals. Different from people, animals may have the bacterium without suffering any illness. The bacterium can contaminate animal products including dairy products and meats, which in turn cause listeria in the consumers. Some of the foods with a high risk of contamination include:

1. Fruits

Cantaloupes and other melons can pick up the bacteria. What’s more, any fruit that is sprayed or washed with water that is contaminated with listeria will be contaminated as well. Luckily, listeria can be found just on the outside of any fruit but it does not penetrate through its flesh.

2. Foods that Have Been Refrigerated for a Long Time

Where does listeria come from? Refrigerated food is another answer. Listeria bacterium differs from other types of bacteria in thatrefrigeration will not prevent the bacteria from growing; instead, it can grow under refrigeration. Uncooked ready-to-eat foods are likely to have listeria,and cooking food at high heat will kill the bacterium.

3. Root and Ground Vegetables

Vegetables grown in the soil such as squash, potatoes, carrots, and beets may contain listeria. Vegetables are the healthiest foods in your diet, so it is unwise to avoid such vegetables; instead, you can wash them thoroughly before cooking and peel where appropriate. Wash vegetables before and after peeling because some bacteria may be transferred to your hands as you peel.

4. Raw and Canned Seafood

Smoked seafood, preserved fish, and raw seafood are also highly likely to be contaminated with listeria bacterium.

Who Is Most Likely to Get Listeria?

About 2,500 people in the United States suffer serious illnessesfrom listeriosis each year and 500 of them lose their lives. These statistics highlight the need to answer the question where does listeria come from? The people at risk include:

• Pregnant women: Their risk of listeriosis is 20 times more than that of other healthy adults. One third of listeriosis cases affect pregnant women.
• Newborns: Newborns even suffer worse effects of the infection than pregnant women during pregnancy.
• AIDS patients: Their risk of getting listeriosis is 300 times more than that of individuals with normal immune systems.
• People with impaired immune systems.
• People with cancer, kidney disease, and diabetes patients.
• The elderly.

Healthy adults and children will not suffer serious effects of listeriosis.

What Can You Do to Prevent It?

Where does listeria come from? The answers to this question point to some of the ways of preventing listeriosis. You can reduce your risk of listeriosis in the following ways:

• Cook foods from animal sources thoroughly such as pork, beef and poultry.
• Wash all vegetables thoroughly before cooking or eating.
• Store uncooked meats separately from cooked foods, vegetables and ready-to-eat foods.
• Avoid taking raw or unpasteurized milk or food products made using raw milk.
• Wash your hands and kitchenware thoroughly after preparing uncooked foods.
• Eat ready-to-eat and perishable foods as soon as possible.

People at high risk of listeriosis can prevent the infection by combining the recommendations outlined above with the following measures:

• Avoid eating luncheon meats, hot dogs, and deli meats unless if they are reheated until they are steaming hot.
• Avoid contaminating other foods and utensils with fluids from hot dog packages. Wash your hands thoroughly after handling deli meats, hot dogs and luncheon meats.
• Avoid eating soft cheeses including brie, feta, and camembert, Mexican and blue-veined cheeses. Eat cheese with a label that clearly states that it is made from pasteurized milk.
• Eat canned or shelf-stable instead of refrigerated meat spreads and pates
• Avoid refrigerated smoked seafood unless it is stored in a cooked dish. 

What Will Be the Symptoms of Listeriosis?

The symptoms of listeria appear 3-70 days after infection but are more likely to appear after 21 days. The common symptoms include muscle aches, nausea, fever, and diarrhea in a few cases. In case the infection spreads to the nervous system, the patient experiences lack of balance, stiff neck, convulsions, confusion and a headache. People with a weakened immune system may get a brain infection or meningitis if the bacteria invade the central nervous system. Pregnant women will experience flu-like symptoms that are mild, but the severe infection may lead to a stillbirth or miscarriage. Newborns experience subtle symptoms in the first week or later, which include poor feeding, fever and irritability.

How Can You Treat Listeriosis?

Any infected person who is not pregnant does not need treatment. Listeriosis symptoms disappear within a few weeks. Pregnant women who get listeriosis should ask your doctor firstly, and take antibiotics to avoid infecting the fetus or baby. Babies suffering from listeriosis should take the same antibiotics given to adults. The doctor may combine different antibiotics until the cause of listeriosis is established.