CDC Lists Top Food Pathogens

Aug. 15, 2010— -- Surveillance data on foodborne disease outbreaks in 2007 revealed that norovirus and salmonella contamination were the leading causes, with poultry, beef, and leafy greens the most common foods involved, the U.S. Centers for Disease Control and Prevention reported.

The analysis also indicated that no cause was ever found for about one-third of outbreaks and a quarter of the victims, according to a report from CDC researchers in the Aug. 13 issue of Morbidity and Mortality Weekly Report.

Nearly 1,100 outbreaks involving 21,244 individual illnesses were covered by the data, supplied by public health laboratories in all 50 states, the District of Columbia and Puerto Rico.

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The CDC researchers noted that these were just a handful of the estimated 76 million illnesses occurring in the U.S. annually from contaminated food.

Of the 734 outbreaks with known etiologies in 2007, 320 involved bacterial pathogens, 324 were traced to viruses, 49 involved chemical contamination (mostly of microbial origin), and five were parasitic infections. Another 36 had more than one cause.

All but seven of the viral outbreaks stemmed from norovirus, which gets into food products when infected workers fail to wash their hands.

In an accompanying commentary, the MMWR's editors said the 2007 figures for norovirus outbreaks were actually less than in previous years, perhaps because of growing population immunity.

The average annual number of outbreaks in which norovirus was confirmed or suspected from 2002 to 2006 was 338 with a mean of 10,854 illnesses. In 2007, the corresponding totals were 317 and 8,024.