The elderly and pregnant women -- especially Hispanic pregnant women -- face the highest risk from Listeria food poisoning, federal health officials say. A new Vital Signs report by the Centers for Disease Control and Prevention says Listeria can cause serious infection in certain vulnerable groups, resulting in higher rates of hospitalization and death than most other bacteria commonly spread by contaminated food. Adults age 65 and older are four times more likely to get Listeria than the general U.S. population, but pregnant women are 10 times more likely get Listeria and pregnant Hispanic women are 24 times more likely, the report said. The elderly, pregnant women, newborns and people with other health conditions that weaken their immune systems make up 90 percent of reported U.S. Listeria infections, the report said. Key findings of the report include: -- More than 1,650 Listeria illnesses were reported to the CDC in 2009-11. -- About 20 percent of infections caused a death. Deaths primarily occurred among older people and as miscarriages or stillbirths. -- Pregnant women who have listeria often have only mild symptoms or fever, but their infections may result in miscarriage, premature labor and serious illness or death in newborn infants. -- During the three-year study period 12 outbreaks sickened 224 patients in 38 states. -- Of the 10 outbreaks with an identified food source, six were linked to soft cheese -- mostly Mexican-style cheeses -- and two to raw produce, whole cantaloupe and pre-cut celery.