Listeriosis, commonly called listeria, is a food-borne illness caused by the bacteria Listeria monocytogenes. The illness is mainly threatening to elderly people, young children, pregnant women and their fetuses, and people with compromised immune systems (such as those with cancer or AIDS). It can, however, sicken a perfectly healthy person on occasion. Pregnant women, who may not even develop symptoms, can pass the illness on to their unborn child, who can be born infected with the disease. About five in one hundred humans carry this bacteria in their body without being harmed by it.
Listeria originates in soil and water. It can come from cattle who carry the bacteria without becoming ill from it. Vegetables can be contaminated if fertilized with manure from infected cattle.
The bacteria are easily killed with heat, so pasteurized foods are less likely to be infected. Cooking foods and washing vegetables with extreme care are also ways of reducing risks. If you or a loved one are in an at risk category, thoroughly heat all lunch meats and hot dogs, and avoid soft cheeses. Also avoid smoked, refrigerated seafoods. Of course, always be sure to wash off cutting boards, storage containers, and the utensils that have touched uncooked meats. Never allow uncooked meats to touch vegetables or fruits as this can cause cross-contamination. Unlike some foodborne pathogens, cold temperatures will not kill listeria, so refrigeration is not sufficient to prevent the illness.
Symptoms of listeriosis can include fever, muscle discomfort, diarrhea, nausea, vomiting, dizziness, headache, stiff neck, disorientation, or convulsions. Infants can exhibit lethargy, labored breathing, and problems feeding in addition to the other symptoms. A doctor can do a simple blood test to diagnose the problem. Additionally, a spinal tap or stool sample can reveal the presence of the bacteria in the body. The bacteria can infect not only the gastrointestinal system, but also the nervous system and bloodstream in extreme cases. Interestingly, it can take as long as seventy days from the time of exposure for symptoms to develop. Typically, however, symptoms appear within a week to a month.
Antibiotic is the treatment of choice, since the illness is bacterial in origin. Usually ampicillin is the antibiotic that is given, but it is sometimes used in combination with another antibiotic.
According to the CDC, there are about 2500 cases of listeriosis per year in the United States, and of these, about one in five are fatal. About 30 percent of cases are in pregnant women, and about 70 percent of cases are in people with compromised immune systems.