Listeriosis is a foodborne infection caused by the bacteria listeria, named for Joseph Lister , a surgeon and pioneer of antiseptic surgery. There are 10 different species of Listeria; The variant that most affects humans is Listeria monocytogenes. It is an unusual or rare zoonosis in humans, but when it does occur, it is extremely serious. It is usually caused by eating contaminated food and about 20-30% of listeriosis cases are fatal.
Symptoms
The initial symptoms of listeriosis may not be apparent for some time. The incubation period is variable and can range from 11 to 70 days after consuming food with the bacteria. The symptoms are: muscle aches, fever, flu-like symptoms, nausea, and diarrhea. While it is true that for many people, a Listeria infection goes unnoticed, in other people, it will spread to the nervous system where symptoms can include: headache, confusion, stiff neck, tremors and seizures, and loss of balance. .
In individuals at increased risk of infection (children, people over 65, pregnant women, people with AIDS, cirrhosis, diabetes, or those who have had their spleen removed or are undergoing chemotherapy treatment), listeriosis can lead to a blood infection. severe (septicemia) or inflammation of the membranes around the brain (meningitis).
If the listeriosis infection spreads to the brain, the results can be serious and may include:
– Cranial nerve palsy: paralysis and tremors.
– Encephalitis: inflammation of the brain.
– Meningitis: inflammation of the membranes that cover the brain and spinal cord.
– Meningoencephalitis: a combination of meningitis and encephalitis.
– Brain abscesses: accumulation of pus located within the brain.
Symptoms during pregnancy or for newborns
Pregnant women are 10 times more likely to develop listeriosis than the general population. The incidence of listeriosis during pregnancy is 12 per 100,000 people, compared to 0.7 per 100,000 in the general population. While the mother with Listeria infection may not show any external symptoms, the unborn baby can be severely affected. Listeriosis can lead to miscarriage or premature labor. And there is the possibility that a newborn could suffer a life-threatening infection in the days and weeks after birth.
Causes
Listeriosis is caused by listeria, a type of bacteria found in water, soil, and feces. Humans become infected by eating foods that harbor the bacteria.
The most common foods that cause listeriosis flare-ups are deli meats (such as shredded meat) and unpasteurized dairy products. However, other foods can also cause sprouts, including caramel apples, melons, and cabbages fertilized by sheep manure.
Diagnosis
Listeriosis is diagnosed by a blood test. Your urine or cerebrospinal fluid may also be tested.
Prevention
Although listeriosis is rare, there are several ways to further reduce the chances of getting infected; These precautions are especially important during pregnancy:
– Cleaning: wash hands with soap and warm water before preparing food. Clean utensils and work surfaces in the same way.
– Raw vegetables: scrub with warm water with a brush.
– Cook well: make sure that the meat and egg dishes are fully heated.
– Cheese: avoid soft cheeses, including brie, feta, camembert, cheeses with blue veins, or Mexican-style cheeses such as queso fresco, panela, and white cheese; unless the label clearly specifies that the product was made with pasteurized milk.
– Meat: avoid cold meats, such as shredded meat or hot dogs unless they are cooked at a high temperature before eating.
– Smoked Seafood: Avoid refrigerated smoked seafood unless it is cooked well before consumption.
Regarding ‘Listeria monocytogenes’
It is one of the most virulent foodborne pathogens.It can flourish with or without oxygen and, unlike many other bacteria, it can thrive and reproduce at temperatures as low as 0 ° C.
It has been found in at least 42 species of wild and domesticated animals, and 17 species of birds.The bacteria have been isolated from oysters, fish, crustaceans, ticks, and flies.
Some studies suggest that up to 10% of human gastrointestinal tracts contain L. monocytogenes. Its hardy characteristics, combined with its relative ubiquity make Listeria a serious and ongoing concern.
This pathogenit enters the host through the intestines and first infects the liver.In the liver, the bacteria multiply until the host’s immune system tackles it; At this stage, the vast majority of infections end. However,In immunocompromised people or others at risk, the infection can continue and eventually travel to the brain.
Listeria bacteria can survive inside immune cells like macrophages. It is also capable of hijacking cellular machinery and tricking cells into attracting bacteria inside.
Inside the cell, bacteria can multiply and spread to neighboring cells, safe from the immune system. This ability to live inside human cellsmakes it unusual, dangerous, and very difficult to deal with.
We have spoken with Dr. Anna Mallafré, a gynecologist at Doctoralia, regarding listeriosis.
Apart from shredded meat, in what other foods or environments could we find this bacillus?
“The main route of transmission of this bacterium is through the consumption of contaminated food, although cases of direct transmission from animals to humans and between humans have also been seen. Unlike other bacteria, L. monocytogenes can grow and multiply in some foods inside the refrigerator. Likewise, this bacterium can multiply in acidic conditions and in environments with high concentrations of salt. “
“This microorganism is found in the soil, in vegetation and in animals. As for food, it can be found in unpasteurized (raw) milk or in soft cheeses made with unpasteurized milk, in products such as sausages, hotdogs , patés , sandwich meats and cold cuts (cold cuts), in smoked fish and seafood, in prepared salads or when consuming fruits and vegetables contaminated through soil or manure used as fertilizer. Listeria epidemic has also been described after consuming open melons without refrigeration and sometimes also in sprouts, which need warm and humid conditions to sprout and grow, conditions are also ideal for bacteria to grow.In risk groups, it is important to try to eat fresh food, the same day and avoid ingesting the remains of previous days “, comments the expert.
What can we do to prevent?
“To prevent listeriosis, in the first place , strict hygienic-dietetic measures must be followed. The first is based on the home, you have to keep the refrigerator very clean, avoid spills, with the food well wrapped with plastic wrap, or in the refrigerator in tuppers and separate the food well. Clean up spills. Different knives and boards should be used to cut meat, fish and vegetables …
Dr. Mallafré summarizes the most important things to take into account:
-
“Try to cook daily and avoid consuming food scraps from one day to the next. Discard food out of the refrigerator for more than two hours or even after an hour if the ambient temperature exceeds 32ºC.
- Store “ready-to-eat” foods at 4 ° C or below. Check the actual temperature of the fridge with external thermometers.
- Use perishable and “ready-to-eat” foods as soon as possible.
-
Make sure that the food is freshly cooked, especially if we eat outside the home.
-
Cook products derived from cattle, poultry and fish properly.
-
Wash and peel fruits and vegetables before consuming them.
-
Do not consume unpasteurized dairy.
