Listeria monocytogenes, a bacterium often associated with foodborne illness outbreaks in cheese and fresh produce, killed approximately one in five Americans it infected between 2009 and 2011, according to a new Vital Signs report released by the U.S. Centers for Disease Control and Prevention Tuesday. Though experts called infections from Listeria rare, the pathogen still ranks as the third leading cause of death from food poisoning. The CDC cataloged more than 1,651 Listeria infections during the three-year period of 2009 to 2011. The pathogen affects some demographics much more severely than others. People over the age of 65 were found to be four times more likely to fall ill from Listeria infection compared to the general U.S. population. Pregnant women were 10 times more likely to fall ill. In particular, pregnant Hispanic women were 24 times more likely than the general population to contract listeriosis. While the women themselves would typically face only mild symptoms or fever, their infection increases their risk of miscarriage, premature labor or the infant’s death. “Listeria strikes particularly hard at people who can’t fight it off,” said CDC Director Tom Frieden in a conference call to reporters. The CDC’s report involved examining 12 foodborne Listeria outbreaks that sickened 224 people in 38 states. From those, six were connected to cheese, including five from soft cheeses made with pasteurized milk — particularly Mexican-style queso fresco. Another, the cantaloupe outbreak of 2011, became one of the deadliest foodborne illness outbreaks in U.S. history. Since the 1990s, advancements in genetic fingerprinting of bacteria have allowed health investigators to uncover more Listeria outbreaks, leading to improvements in food manufacturing to reduce the risk of Listeria contamination, the report said. Those measures led to a 25 percent reduction in Listeria infections by the early 2000s, but that rate has plateaued. Frieden said that it was the state of Colorado’s rapid response to the cantaloupe outbreak that prevented even more lives from being lost. “They were monitoring trends and they noticed in just days that there was an increasing number of listeria cases,” he said. “They worked over a holiday weekend. They interviewed patients. They identified cantaloupe as the likely vehicle. They got it off the shelves, and they saved lives because they did that.” The President’s fiscal year 2014 budget has proposed a $40 million investment in the CDC’s Advanced Molecular Detection Initiative, which would improve outbreak detection and the protection of public health, the report added.