Listeriosis is a serious infection that you can get by eating food contaminated with the bacterium Listeria monocytogenes. Pregnant women and their developing babies – as well as newborns, people with weakened immune systems, and the elderly – are particularly susceptible to Listeria, which can cause a blood infection, meningitis, and other serious and potentially life-threatening complications. The primary threat for a pregnant woman is the devastating effect this disease may have on her pregnancy and her baby.
Fortunately, the illness is relatively rare: The Centers for Disease Control and Prevention (CDC) estimates that about 2,500 people contract listeriosis in the United States every year. About a third of reported cases occur in pregnant women.
How could listeriosis affect me and my baby?
Unless you have some underlying disease that affects your immune system, it's unlikely for listeriosis to seriously affect your health. But even if it doesn't make you seriously ill, the infection can have grave consequences for your developing baby, especially if you're not treated promptly.
Listeria can infect the placenta, the amniotic fluid, and the baby, and can cause miscarriage or stillbirth. Infected babies who survive are likely to be bornprematurely. Many will be born severely ill or get sick soon after birth, with problems that can include blood infection, difficulty breathing, fever, skin sores, lesions on multiple organs, and central nervous system infections such as meningitis.
Some newborns of infected mothers appear healthy at birth and first have signs of infection, usually meningitis, a week or even several weeks after delivery. This so-called "late-onset listeriosis" may be the result of a baby becoming infected during labor and birth (an infected woman may harbor the bacteria in her cervix, vagina, or gastrointestinal tract), or, more rarely, from transmission from a source other than the mother.
Unfortunately, many infected babies will die or suffer long-term consequences.
How will I know if I have listeriosis?
You might not know. Some people have no symptoms. Others have a fever and other flu-like symptoms, such as chills, aches, and headache; back pain; or possibly gastrointestinal symptoms. Less commonly, the infection attacks your central nervous system. If that happens, you may become quite ill and have symptoms such as severe headache, stiff neck, confusion, dizziness, or even convulsions.
Call your healthcare practitioner immediately if you have any symptoms of listeriosis. Stomach symptoms, if you get them, generally appear within 48 hours, but other symptoms usually show up two to six weeks or more after you're infected. You'll need a blood test to find out whether your symptoms are caused by listeriosis.
How is listeriosis managed?
You'll be given IV antibiotics, which will treat your infection and may help protect your baby. Ultrasoundswill be done to check for problems and to see how your baby is growing.
What can I do to avoid getting infected?
Here are some guidelines for avoiding this food-borne illness:
- Cook all meat, poultry, and fish thoroughly. Use a food thermometer to test the internal temperature of meat. Most meat should be cooked to a temperature of 160 degrees Fahrenheit (or 180 degrees F in the thigh for whole poultry). If you're not actually measuring the temperature of the meat, cook it until it's no longer pink in the middle. Fish should be cooked until the flesh in the middle is opaque. And be sure not to sample your food before it's done.
- Reheat leftovers thoroughly. Because Listeriacontamination can also occur after food has already been cooked or processed, and the bacteria can survive – and, unlike many bacteria, continue to grow – in the refrigerator, heat all previously cooked leftovers to 165 degrees F or until they're steaming hot. If you use a microwave, cover the food with a lid or microwave-safe plastic wrap to hold in moisture and provide safe, even heating. (Turn back a corner to allow the steam to vent.) Allow the food to stand for a few minutes after microwaving to help complete the cooking. You can use a clean food thermometer to make sure the reheated food has reached 165 degrees F.
- Avoid deli foods unless you heat them. For the same reason, don't eat cold cuts or deli meat, refrigerated pâtés or meat spreads, or refrigerated smoked or pickled fish unless they're cooked until they're steaming hot (say, on a pizza or in a hot sandwich). And even though hot dogs are precooked, be sure to cook them until they're steaming hot as well. Canned or shelf-stable products that don't need to be refrigerated should be fine to eat. Avoid prepared salads from delis and supermarkets, especially those containing eggs, chicken, or seafood. Also, you may need to skip that potato salad that's not on ice at the picnic or meat that's not kept steaming hot at the buffet. Unless you're positive that the food has been safely prepared and has been sitting out for less than two hours (one hour on a very warm day), it's not worth the risk.
- Avoid unpasteurized (raw) milk. That includes both cow and goat's milk – and food made with them. Don't eat soft cheese such as feta, Brie, or Camembert; blue-veined cheese; or Mexican-style cheese such as queso blanco, queso fresco, or panela, unless the label clearly states that it's made from pasteurized milk. Cottage cheese, ricotta, cream cheese, processed cheese (such as American), and hard cheese (such as cheddar and Parmesan) are generally considered safe, as are cultured dairy products like yogurt and buttermilk. But to be on the safe side, read the labels on all dairy products to make sure they're made with pasteurized milk.
- Wash all produce. Thoroughly wash or peel all fruits and vegetables before eating them.
- Avoid sprouts. You might choose to forgo raw sprouts until after your pregnancy. (Alfalfa sprouts caused an outbreak of listeriosis in March 2008.)
- Avoid contaminating food that's ready to eat.Keep any potentially contaminated food (such as unwashed produce; uncooked meat, poultry, or seafood; hot dogs; and deli meat) separate from clean produce and from cooked and ready-to-eat food. Wash counters, cutting boards, dishes, utensils, and your hands with hot soapy water after contact with potentially contaminated food – and before you handle clean produce or cooked meat so you don't contaminate your food.
- Clean sponges and dishcloths regularly. Keep in mind that dishcloths and sponges can harbor bacteria. Wash dishcloths regularly in hot water, and clean any sponges in the dishwasher or microwave. Dry clean dishes, utensils, surfaces, and your hands with a clean dishtowel or use a paper towel.
- Don't keep food around too long. Consume perishable and ready-to-eat food as soon as possible after you buy it, especially once you've opened it – even if it hasn't yet passed the "use by" date. This date refers to unopened products.
- Check the temperature in your fridge and freezer. As a general precaution to help protect your food from contamination from a variety of disease-causing organisms, make sure your refrigerator is set between 35 and 40 degrees F and your freezer at or below zero. Use a refrigerator thermometer to confirm the temperature.
Remember that a cold fridge is helpful but not fool-proof:Listeria is a hardy organism that can survive and even continue to grow in cold temperatures (albeit more slowly). That's why you should always heat leftovers and precooked ready-to-eat food until they're steaming hot. It's also why it's a good idea to clean your refrigerator regularly.
