Old people and pregnant women face the highest risk of hospitalization and death from listeria, according to the US Centers for Disease Control and Prevention (CDC).
The agency also identified that recent outbreaks were linked to soft cheese and raw produce.
Adults aged 65 years and older are among the groups most affected; they are four times more likely to get listeria infection than the general US population.
Pregnant women are 10 times more at risk and pregnant Hispanic women are 24 times more likely.
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).
CDC recommends that no one consume unpasteurized milk or soft cheese made from unpasteurized milk. Soft cheeses can be crumbly, like queso fresco, or soft and spreadable.
People at higher risk for listeria infection should be aware that some Mexican-style soft cheeses, like queso fresco, made from pasteurized milk have caused illnesses, possibly because of contamination during cheese making.
Listeria can cause serious infection in certain groups, resulting in higher rates of hospitalization and death than most other bacteria spread by contaminated food, said the Vital Signs report.
The report, which provides a national view of 2009-2011 illness rates, found more than 1,650 listeria illnesses were reported to CDC over a three-year period.
“Listeria strikes hard at pregnant women, the elderly, and people with weakened immune systems, sending many to the hospital and causing miscarriage or death in as many as one in five,” said Tom Frieden, M.D., M.P.H., Director, CDC.
“We need to develop new cutting edge molecular technologies to help us link illnesses and outbreaks to foods faster to prevent illness and death, which is why the President’s Budget proposes investing in new tools to advance this work.”
Recent outbreaks have been linked to foods not usual vehicles of listeria infection, highlighting opportunities for control measures and the need to identify more foods causing infection and keep the pathogen from entering the food supply.
“The lower rates of listeria infection attributed to meat and poultry over the past decade point to the success of prevention-based policies and industry best practices,” said Elisabeth Hagen, M.D., Undersecretary for Food Safety, US Department of Agriculture.
“However, important work remains if we hope to continue this momentum. Additional research and continual monitoring of evolving risks will allow us to develop policies that further reduce these illness rates.”
The President’s FY 2014 Budget proposes an investment of $40m for CDC’s Advanced Molecular Detection Initiative, which would aim to strengthen the public health system’s ability to protect communities from disease and foodborne illness.