Listeria More Dangerous Than First ThoughtNov 24, 2009 | Parker Waichman LLP We routinely report about the problems linked with food borne pathogenic illnesses, including Listeria monocytogenes. And, while we have continually stressed that Listeriosis, the infection caused by the Listeria pathogen, is dangerous and can often be deadly, an emerging study reveals that the risk is even greater than first believed.
Medical News reported that the study found risks for severe effects of Listeria exposure in sensitive groups might occur at lower doses than prior studies suggested. Fetal or infant death in expectant mothers who consume food tainted by one million cells of Listeria monocytogenes in, for instance, soft cheeses is believed to occur at 50 percent, said Medical News. This means that about five stillborn births could occur for every 10 expectant mothers exposed to this amount of the pathogen; an earlier study found that over 10 trillion cells could result in stillbirths in half of the exposed pregnant population, reported Medical News, a significant difference.
Listeriosis can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems. Healthy individuals may suffer only short-term symptoms, such as high fever, severe headache, stiffness, nausea, abdominal pain, and diarrhea. In pregnant women, Listeriosis can result in miscarriage, stillbirth, or birth of a baby suffering from the infection. Pregnant women are about 20 times likelier than others to be infected, with about one-third of all Listeriosis cases occurring during pregnancy.
Listeria is responsible for an estimated 2,500 illnesses in the United States annually, with about 200 in every 1,000 cases resulting in death. Listeria infection can take days, even weeks, to develop and can present in anything from a mild flu-like illness to meningitis and septicemia.
Medical News explained that about one-third of the all Listeriosis cases seen each year involve fetuses or newborns. Also, said Medical News, while women can become infected during any phase of pregnancy, cases are generally reported during the third trimester. Once infected, expectant mothers might not exhibit symptoms or may only complain of feeling as if they have a mild flu; however, they can pass the illness to their babies with Listeria causing spontaneous abortion in the first trimester and stillbirth, premature birth, or birth of a seriously ill baby in later trimesters, according to Medical News.
After Listeria enters the intestines, it spreads to “the blood, liver, placenta, or the central nervous system,” said Medical News. The disease can take a few days to manifest as gastroenteritis, two-to-three weeks for meningitis—as many as three months when a patient is pregnant. “Headache, stiff neck, confusion, loss of balance, or convulsions” are seen when the infection attacks the nervous system, Medical News pointed out.
"We're not saying there's a new epidemic here, we're suggesting we've come up with a more accurate method of measuring the risk and how this deadly bacteria impacts humans, especially the most medically vulnerable among us," said Mary Alice Smith, Ph.D, of the University of Georgia. Smith is a study co-author. "Listeriosis is likely occurring from exposure to lower doses than previously estimated," Smith added.