What's the difference between listeria and salmonella and are you at risk?


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Watching what you eat is not always just a case of calories and carbs. In our ever more automated and mass-producing world, hygiene has become a recurring difficulty. Hardly a month goes by without a food product recall or a stomach-churning horror story focusing on a popular eatery. The two most common words we hear are salmonella and listeria — but what exactly are they, what are their effects and what can you do to stay safe?


What is salmonella?

Salmonella — or Salmonella enterica — is a bacterium that causes a form of food poisoning known as salmonellosis. The Centers for Disease Control and Prevention (CDC) says that, though most people recover without treatment, in some the diarrhea may be so severe that the patient needs to be hospitalized to prevent dehydration and to stop a transfer of the bacteria from the intestines to the blood stream — which can cause much more serious problems. CDC figures suggest around 1.2 million illnesses every year are caused by salmonella in the U.S. resulting in up to 450 deaths.

The bacterium can pass into food from the feces of people or animals — including pets. Salmonella bacteria can also get into food during processing and infection is often caused by those preparing food not washing their hands effectively before handling it. It is extremely advisable to wash your hands thoroughly when cleaning up after pets (particularly if they have diarrhea) as well as after handling pets such as reptiles, baby chicks and ducklings as well as small rodents such as hamsters and mice as these often carry the bacterium. According to WebMD, those at greatest risk from the infection are babies and young children, older adults and people with compromised immune systems so make sure children learn how to wash themselves correctly after handling pets.


Symptoms and treatment of salmonella

The infection most often affects meat, milk and eggs (and mayonnaise) but sometimes hides in vegetables, and even nuts too — if, say, the water used on the crop has been exposed to animal cross-contamination. The infection causes diarrhea, abdominal cramps and fever — usually within one to three days of the ingestion of infected food and symptoms can last as long as a week. The gastrointestinal problems caused by salmonella infection usually go completely away though, the CDC says, "it may be several months before your bowel habits are entirely normal." There have been some cases of patients who have had salmonellosis developing arthritis although this by no means common.

The CDC offers some advice for avoiding problems with salmonella:

  • Cook poultry, ground beef, and eggs thoroughly. Do not eat or drink foods containing raw eggs, or raw (unpasteurized) milk.
  • If you are served undercooked meat, poultry or eggs in a restaurant, don't hesitate to send it back to the kitchen for further cooking.
  • Wash hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with raw meat or poultry.
  • Wash hands with soap after handling reptiles, birds, or baby chicks, and after contact with pet feces.
  • Avoid direct or even indirect contact between reptiles (turtles, iguanas, other lizards, snakes) and infants or immune-compromised persons.
  • Don't work with raw poultry or meat, and an infant (e.g., feed, change diaper) at the same time.


What is Listeria?

Listeria — more properly known as Listeria monocytogenes — is the bacteria that causes listeriosis, an infection of the gastrointestinal tract caused by eating contaminated food. Though it can affect anyone, it is most hazardous to the elderly, babies, pregnant women and people with compromised immune systems. According to the CDC, around 1,600 people are made sick by the bacterium every year and more than 90 percent of these are in the groups most at risk. The infection can occur in the soil, after processing (in the case of dairy products) or be transferred from animals that are carriers.

One of the reasons listeria is so dangerous is its hardiness. Listeria can survive not only on refrigerated food, but also in and around the areas and utensils we use to cook as well as on the grocery shelves from which we select produce. It also thrives, of course, on uncooked foods like deli meats, seafood, cheese and other unpasteurized milk products. Add to this the fact that symptoms of infection might not occur for weeks after ingestion of the bacteria — making it difficult to locate the source — and listeria becomes a serious problem.


Symptoms and treatment of listeriosis

The earliest symptoms of listeriosis are not always easy to identify. WebMD advises that the first signs may include "fever, muscle aches, and sometimes nausea or diarrhea." If left untreated, the infection can spread to the nervous system where a patient may experience headaches, stiff neck, confusion, loss of balance as well as convulsions — pregnant women, they say, might only get "a mild, flu-like illness."

The majority of people who get the illness need hospital treatment — around one in five die as a result of infection. Currently, it can be treated with antibiotics though, as usual, no treatment works better than prevention. Foodsafety.gov has some good tips for those at risk:

  •  Don't consume raw (unpasteurized) milk or foods that have unpasteurized milk in them.
  • Always wash hands, knives, countertops, and cutting boards thoroughly after handling and preparing uncooked foods.
  • Rinse all raw produce thoroughly under a running tap water before eating.
  • Keep uncooked meats, poultry and seafood separate from vegetables, fruits, cooked foods and ready-to-eat foods.
  • Thoroughly cook raw food from animal sources, such as meat, poultry, or seafood to a safe internal temperature.
  • Consume perishable and ready-to-eat foods as soon as possible.
  • Persons in higher risk groups should heat hot dogs, cold cuts, and deli meats before eating them.

The food industry, of course, also needs to play its own part in reducing risk from these and other infections. Following FDA health and safety guidelines is vital if the public are to be protected from avoidable risk. A recent recall of frozen corn by a manufacturer in Brockport, NY, shows just how modern production methods and distribution networks can potentially turn a controllable, local issue into one that can cause problems nationwide.

Remember that the symptoms described above can have many causes. If you're worried about aches, cramps, upset tummy or any other issues, see your doctor as soon as possible.