ATHENS, GA― A new study conducted by researchers at the University of Georgia, Athens found the risk for severe effects of ingesting the bacterial pathogen Listeria monocytogenes among susceptible populations, particularly pregnant women, may occur at lower doses than previously thought (Risk Analy. 2009;29(11):1495–1505).
The study found risk of fetal or infant mortality among pregnant women who eat food containing one million cells of L. monocytogenes in soft cheeses and other foods is estimated at about 50 percent. This translates into five stillbirths for every ten pregnant women exposed to that amount. A previous risk assessment estimated the number of L. monocytogenes cells that would trigger this level of stillbirths at more than 10. The risk assessment focused on consumption of Listeria-contaminated Mexican-style soft cheese by a woman in her third trimester of pregnancy, and used non-human primates and guinea pigs for the models.
“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., a study co-author. Extrapolating estimates from data in tests on laboratory animals showed “Listeriosis is likely occurring from exposure to lower doses than previously estimated.” The research also “shows studies using animal test subjects with physiologies more comparable to humans are more promising for future pathogen research endeavors.”