Listeria Facts You Need To Know

Fresh slice canteloupe( — Are you at risk from listeria, the deadly bacteria now in the news because of contaminated cantaloupe? The death toll is rising in what is now the largest outbreak of food-borne illness in more than a decade.

Suddenly the spotlight is on listeria. What is it? Where is it? Who’s at risk? What are the symptoms? What are the best ways to avoid contamination?

What is listeria?

Like the famous mouthwash Listerine, Listeria monocytogenes was named after antiseptic pioneer Joseph Lister. It’s a very common bacterium with an unusual trait: It can grow at refrigerator temperatures. And it can build up in food-processing plants, where it can survive for years.

Where is listeria found?

Listeria is found in soil, groundwater, animal feed, sewage, and even dust. It primarily lives in soil, where the bacterium eats decaying plants. But once it makes its way into the food supply and is eaten by a human, listeria transforms into a very different bug — one that can live inside human cells.

What foods are often most contaminated with listeria?

Because listeria can grow at refrigerator temperatures and high salt concentrations, cured meats kept in the refrigerator can support listeria growth. Unpasteurized milk, unpasteurized milk products, refrigerated smoked seafood, and raw sprouts have also been implicated in listeria outbreaks. But listeria can grow on many different foods, particularly if they are stored in a contaminated refrigerator. The nationwide U.S. listeria outbreak of 2011 — the largest in more than a decade — was traced to cantaloupes.

What should I do if I bought a suspect cantaloupe or other food?

All of the cantaloupes in the current listeria outbreak came from Jensen Farms, a Colorado-based company. Although some of these cantaloupes carry a distinctive sticker, not all contaminated fruit will be marked. Ask your grocer if the cantaloupe you bought is from Jensen Farms.

If you suspect that you have a contaminated cantaloupe, do not try to wash off the listeria. Griffin of the CDC notes that it’s not clear whether a listeria-contaminated melon carries listeria on the inside as well as on the outside.

So dispose of suspect cantaloupe in a sealed bag, and make sure it will not be eaten by animals or other people.

If there is a recall or any suspicion that there is listeria in your food — be it lettuce, cheese, or hot dogs — throw it out. Do not try to wash the food because there is no way to ensure that the listeria is just on the surface. Listeria cannot be seen and it does not change the way the food looks, so always play it safe. Officials also ask that you wrap the food in a plastic bag before throwing it out to prevent another person or an animal from eating it.

As for all other produce, the FDA advises to wash all fruits and vegetables under running water just before eating, cutting, or cooking, even if you plan to peel the produce first. Scrub firm produce such as melons and cucumbers with a clean produce brush.

Is there anything else I should do if I’ve bought listeria-contaminated food?

One study found that once a listeria-contaminated food product was in a person’s home, 11% of all food samples in their refrigerators also were contaminated. Nearly two-thirds of people with listeria infections turn out to have listeria growing in their refrigerators.

So clean your refrigerator if you think you may have purchased a contaminated cantaloupe. Wash the fridge thoroughly with soap and water. Then wipe it down with a diluted solution of chlorine bleach.

Who is most at risk from listeria?

The healthy immune system usually keeps listeria in check. Healthy people usually get only mild diarrhea from listeria, if they get any symptoms at all. But immunity wanes each decade after age 60, so the elderly are at risk. Pregnancy, especially the third trimester, makes a woman vulnerable to listeria. And people with diseases (such as HIV or diabetes) or who take medications that lower immunity are at high risk.

Why is listeria so deadly?

In most healthy people, the immune system eliminates listeria-infected cells before the infection can spread. But when listeria escapes the gut, it gets into the blood. From there it can spread throughout the body, causing a disease called listeriosis. Listeriosis can cause deadly encephalitis and meningitis, killing some 20% of patients. Listeria causes about 19% of all U.S. deaths from food-borne infections.

Why are pregnant women at high risk from listeria?

Pregnant women usually do not develop serious listeriosis themselves, just a mild flu-like illness. But once listeria gets into a pregnant woman’s blood, it seeks out the placenta. From there it can infect the fetus and cause stillbirth, miscarriage, or preterm birth. During birth from a woman carrying listeria, the bacteria can infect the newborn. Neonatal listeriosis can cause fatal or disabling meningitis.

What are common symptoms of listeriosis?

Listeriosis may start with diarrhea or other intestinal symptoms. But serious disease starts with fever and muscle aches. Other symptoms often include headache, stiff neck, confusion, loss of balance, and convulsions.

How long after eating listeria-contaminated foods do severe symptoms appear?

The time between eating listeria-contaminated food and having listeriosis symptoms ranges from three days to two months. Most people seem to get symptoms within one to three weeks.

What is the treatment for listeriosis?

Because it is so deadly, listeriosis is treated with intravenous antibiotics. Treatment lasts two weeks if the central nervous system is not infected, four weeks if it is. Nearly all patients are hospitalized for at least a few days.

How can you avoid listeria infection?

Here’s the FDA’s advice on how to prevent listeriosis:

• Do not consume unpasteurized milk or milk products.
• Wash hands and any other contacted surfacs after handling raw foods.
• Rinse raw produce thoroughly.
• Keep uncooked meat, poultry, and seafood separate from all other foods.
• Thoroughly cook meat, poultry, or seafood.
• Eat perishable and ready-to-eat foods as soon as possible.
• People at risk should heat hot dogs, cold cuts, and deli meats before eating them.

If you suspect that you may have contacted listeria, seek medical treatment immediately.