fruits and vegetables
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According to a new report from the U.S. Centers for Disease Control and Prevention (CDC), raw food products, such as fruits, vegetables and soft cheese, are the most common sources of listeria food poisoning. However, some demographic groups are at greater risk than others and should be extremely cautious when consuming such products. As many as 90 percent of the people affected by the foodborne disease are elderly, pregnant women, newborns or have weakened immune systems, the CDC said.

The Vital Signs report
, released June 7, examined data on listeria outbreak cases in the United States between 2009 and 2011. Researchers found that pregnant women were 10 times more likely to be seriously affected by food poisoning than other people, with the risk found to be highest among pregnant Hispanic women, who are 24 times more prone to developing complications. Similarly, people over the age of 65 are four times more likely to fall ill with a listeria infection, compared to the general population, the CDC said.

CDC director Dr. Tom Frieden warned that listeria was very dangerous for certain people and can cause hospitalization, miscarriage and even death. He explained that new molecular technologies need to be developed to detect outbreaks faster and to track them to the original source, so that they could be prevented from spreading. The Obama administration's budget proposes more funding for this particular area of research and development, so that more advanced tools to facilitate that might be put forward, Frieden said.

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Over the three years in which the study was being conducted, the CDC received reports of more than 1,650 listeria illnesses. About one in five cases were fatal, particularly among senior citizens or as stillbirths and miscarriages, the study showed. Pregnant women should be extremely cautious as the disease may sometimes pass unnoticed and they may experience nothing but a mild fever, but the consequences for the foetus may be grave.

Between 2009 and 2011 there were 224 people in 38 states who fell ill with listeria infection. One of the biggest and most deadly outbreaks occurred in 2011 and was identified as stemming from cantaloupes from one farm. Of the 10 foodborne listeria outbreaks with an identified food source, six were connected to cheese, including five from soft cheeses made with pasteurized milk, particularly Mexican-style queso fresco. Two more outbreaks were linked to raw produce — the cantaloupe outbreak from 2011 and another one related to pre-cut celery, the report said.

There are measures that people can take to prevent being infected with listeria, such as carefully washing fruit and vegetables and drying them before consumption, the report noted.