Listeria

Over the last couple of months, several food poisoning illnesses and deaths have been linked to cantaloupes infected with Listeria. The contaminated cantaloupes were reportedly shipped out of Colorado at the end of July and the beginning of September. Every year upwards of 1,500 people will develop Listeria infections and approximately 250 individuals will die from the disease. The current epidemic has been responsible for about five to eight deaths and 50-plus infections.

Listeria is a class of bacteria that can live in certain animals, soil, and water. Animals can carry the bacteria and not appear ill. It can be present on raw fruits and vegetables when they are harvested or in animals that we consume as meats or dairy products. It can also survive for quite a while in food processing plants, contaminating food during processing.  

Pasteurizing foods during food processing and cooking foods will kill the bacteria; however, some foods may become contaminated after cooking or before packaging. Some strains can grow and multiply even though the food is refrigerated.

Like other “food poisoning” illnesses, Listeria infection mainly affects the gastrointestinal (GI) tract. This means symptoms can include nausea, vomiting, diarrhea, abdominal pain, cramps, and other general symptoms of infection like fever, muscle aches, and fatigue. The term “Listerosis” is used in those cases where the infected individual is exhibiting not only gastrointestinal symptoms, but has systemic or general symptoms as well. This means that the bacteria has become “invasive” and has spread outside the GI tract.   

One of the difficulties in recognizing the disease is that in some cases it can take up to two months for an individual to develop symptoms of the infection. So a person who is experiencing GI symptoms may not associate their current illness with a food they consumed weeks or even months ago.  

Those who are at greatest risk for severe and complicated Listeria infections are the elderly, the immune deficient (cancer, HIV patients), individuals with chronic debilitating disease, newborns, and pregnant women. Healthy individuals who are exposed to the bacteria may have only mild or imperceptible symptoms, overcoming the infection with their normal body defenses. Pregnant women are nearly 20 times more prone to these infections than other individuals.  About one in six, or 17 percent, of Listerosis cases occur in pregnant women. Babies can be born with Listerosis if their mothers consume foods infected with the bacteria.   

Blood and spinal fluid testing can be done to identify the bacteria in those suspected to have Listerosis.  Since the infection is bacterial, antibiotics can be effective in curing the infection. However, even with prompt treatment, deaths can still occur in those who are at particularly high risk.  

Reducing your risk of listerosis involves following common sense food handling rules: Wash your hands before preparing food. Always wash fresh fruits and vegetables before eating them. Avoid eating raw meats and unpasteurized products. Properly cook foods to the recommended temperature and separate uncooked and cooked foods during storage and preparation. Wash utensils and food preparation areas thoroughly.  

The content in this column is for informational purposes only.  Consult your physician for appropriate individual treatment.  Dr. Reynolds practices Family Medicine in Chesterfield.

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