Listeriosis. What You Should Know.

In 2017 South Africa saw the onset of a Listeriosis outbreak that would be deemed the worst documented outbreak (of Listeriosis) in global history.  At the time of writing there are 717 confirmed cases and  over 60 deaths, including at least one pregnant woman.  As South Africa  seeks to find the exact cause of the outbreak,  many of us  are left with questions on how we can protect ourselves and our loved ones.

What is listeriosis?

Caused by Listeria Monocytogenes-a bacteria that is common in soil, water and plants, listeriosis (pronounced lis-TEER-ee-o- is) is an illness that occurs when someone eats contaminated food.

While anyone can be infected by the germ, it usually affects:

• babies and young children
• the elderly
• people with weakened immune systems (cancer, HIV/AIDS)
• pregnant women.

One of the major challenges in tracing the cause of the outbreak is that symptoms can take as long as 70 days to appear. By then most people do not remember what they ate and traces of the food may no longer be available in their homes.

Fortunately, food scientists are specially trained to trace these germs and with time will usually find the source of infection and aim to control it.

What are the symptoms of listeriosis?

While some people may experience nausea and vomiting which usually resolves by itself, severe cases of the condition require immediate medical attention and treatment with antibiotics.

Pregnant women with listeriosis infections may report having a fever and flu-like symptoms such as body pain and overall weakness. In the most severe cases, they may  lose the baby through a miscarriage.

Listeria can also cause a newborn baby to contract meningitis.

People who are not pregnant also complain of  fever, body aches and weakness and may experience extreme headaches, stiff neck, confusion, loss of balance and convulsions.

As seen in South Africa, severe cases of the infection can cause meningitis and death.

What foods are commonly associated with listeriosis? 

Listeria is found in soil, water, food and the guts of healthy animals that we eat for meat.

Vegetables can become contaminated if they are grown in contaminated soil or come into contact with contaminated manure.

At present, the foods known to potentially cause listeriosis include:

1. Unpasteurized milk and dairy products.
2. Raw vegetables grown in contaminated soil or with contaminated manure
3. Ready to eat Deli (Luncheon) meats such as pologny, roast beef, pastrami, hot dogs, vienna sausages
4. Smoked seafood
5. Contaminated animal meats
6. Soft cheese such as feta, brie and camembert

What can you do to prevent listeriosis

People at high risk for listeriosis can protect themselves by:

Avoiding raw (unpasteurized milk) products .

Raw milk is milk that has not been pasteurized to kill harmful bacteria such as listeria, E- Coli and salmonella. Examples of raw milk include:

• all raw animal milk from animals such as cow, goat, sheep
• home fermented/ sour milk (Mukaka wakakora/ Lacto (Zimbabwe), Amasi (South Africa), Mutindi (Tanzania)
• soft cheese.

• Unpasteurized milk may contribute to listeriosis infection.

What is pasteurization?

Pasteurization is a  process in which food is heated to a certain temperature for a period of time so as to kill harmful bacteria. Commonly pasteurized foods include milk and dairy products, juices and eggs.

In recent years, especially in western countries there has been a surge in the number of proponents drinking “raw milk” often suggesting that it may be better for overall health.  At present the research does not support this notion and the Center for Disease Control (USA) states that it can make you sick, especially if you are in the high risk groups.

A few words about pasteurization

• Pasteurization is the process by which food is brought to a certain temperature for a period of time so as to kill harmful bacteria.
• Research indicates that pasteurization does not cause lactose intolerance or allergies nor does it reduce the nutritional content of milk
• Pasteurized milk should be refrigerated. If using ultra-high temperature (UHT) milk (such as Chimombe), keep in mind that the special packaging of this milk allows it to stay unrefrigerated for a longer period of time. However, after opening, that milk is at risk for spoilage and is best if kept in a refrigerator.

TIPS: Check food labels to see if a food is pasteurized and choose sour/fermented milk and soft cheese made from pasteurized milk.

 Avoid  eating cold cuts (Luncheon) meats.

• If you must eat luncheon meats such as polony and other cold cuts, thoroughly heat them until steaming hot before consuming.

Choose hard cheeses such as Parmesan, cheddar and gouda

Thoroughly cook all animal meats.

• Invest in a food thermometer and follow guidelines to ensure that the meat reaches a temperature high enough to kill bacteria.
• The recommended cooking temperatures for meats are:
  • 74° C  (165° F) for  chicken pieces
  • 63 ° C ( 145°F) for steak (turn it twice while cooking)
  • 82° C ( 180°F) for whole poultry
  • 70 ° C ( 158°F) for fish
  • 74 ° C ( 165°F) for shellfish

Rinse raw fruits and vegetables throughly under running water

Since soil is a carrier of bacteria, be sure to remove any visible signs of soil on produce by scrubbing it throughly under clean running water.

Wash and melons and other thick skinned produce throughly too. Even if you do not eat the skin, cutting through it without removing harmful organisms on the outside can transfer bacteria to otherwise uncontaminated fruit.

1. • DID YOU KNOW: Some hospital and restaurant chefs use a special scrub brush to clean hard skinned produce  like melons? 
   • My colleague and Registered Dietitian shows you how to wash produce in this video. 

Avoid cross contamination

Cross contamination happens when one food unintentionally introduces a bacteria to another food. For example, a mother cooking some chicken and vegetables can introduce bacteria from the chicken to her healthy veggies if she uses the same cutting board to cut the chicken and vegetables without washing it throughly with hot soapy water between uses.

Prevent cross-contamination by:

•  using separate cutting boards for meats, produce, fish and ready-to- eat foods
• washing cutting boards with hot water and soap between foods
• storing raw meats and vegetables separately from cooked ones
• storing raw meats below cooked foods or raw vegetables

 Look at expiration dates

Although some foods can be safely consumed past the “use by” or “best by” dates, people at risk for food-borne illness should avoid food that is past its expiration date. Keep in mind that Listeriosis does not have any physical signs of contamination and since it does not have an odor can easily pass the smell test.

If you are not sure if a food is still good, follow the mantra “If in doubt, throw it out.”

Wash your hands.

It seems like a no-brainer but when it comes to food (and health) safety, hand washing is one of the most effective things you can do to keep your food and family safe. But, washing your hands doesn’t mean just splashing water over your hands and drying them on your pants. No does it mean adding a tiny dollop of soap and rinsing it in water.

This is how you wash your hands effectively.

1. Wet your hands under warm or cold water
2. Add  soap and thoroughly lather and scrub for at least 20 seconds (The time it takes for you to sing Happy Birthday TWICE)
3. Rinse hands under clean running water
4. Dry on a clean towel. If no clean towel is available, allow hands to air dry.

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Sources:

1. ServSafe Coursebook. National Restaurant Association. 6th edition
2. Questions and Answers | Listeria| CDC.  
3.  WHO | Listerios;