martes, 17 de noviembre de 2009

Risk of infant, fetal mortality from Listeria higher than believed

Listeria monocytogenes could present a high risk to unborn babies and infants at significantly lower bacterial counts.
The study from the University of Georgia, in the United States, found the risk of foetal or infant mortality among pregnant woman who eat food containing one million cells of the food-borne pathogen Listeria monocytogenes in soft cheeses and other foods is estimated at about 50 per cent. This suggests that five stillbirths could occur when ten pregnant women are exposed to that amount of the bacteria.
Risks at lower bacterial levels
Previous assessments of the hazard estimated that such a miscarriage rate would likely only be reached by exposure to more than 10 trillion Listeria cells. This means that such rates of infants and foetus’ deaths could occur at levels 10 million times less than previously thought, according to the results.
“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 study co-author Mary Alice Smith, Ph.D.
The researchers declared their estimates by extrapolating from test results on laboratory animals, such as guinea pigs, to conclude “Listeriosis is likely occurring from exposure to lower doses than previously estimated”.
The analysis also “shows studies using animal test subjects with physiologies more comparable to humans are more promising for future pathogen research endeavours”, they added.
Listeria monocytogenes is a pathogen sometimes found in soft cheeses made from unpasteurised milk and in processed, ready-to-eat foods such as deli meats, smoked seafood, and raw foods. The pathogen also has been found in pasteurized and refrigerated foods, such as pasteurized fluid milk and soft-ripened cheeses. Listeriosis rarely results in sickness among healthy groups buts can have serious consequences for the medically vulnerable such as the elderly, fetus, infants and those with a weakened immune system.

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