Of the 734 foodborne disease outbreaks with known etiologies in 2007, Norovirus and Salmonella accounted for the lion’s share of reports, according to new data from the Centers for Disease Control and Prevention (CDC), reported in the August 13 edition of Morbidity and Mortality Weekly Report (MMWR) .
No cause was found for about one-third of the nearly 1,100 total outbreaks, which involved 21,244 individual illnesses. Some 320 of the outbreaks were caused by bacterial pathogens; in nearly half of these, including two of the three largest, Salmonella was the cause. The culprit in all but seven of the 324 viral outbreaks was Norovirus, which results from poor hygiene practices by food safety workers.
Norovirus outbreaks were actually down a bit, from 338 in 2006 to 317 in 2007, which MMWR editors speculated could be due to growing population immunity or might simply represent a brief dip between surges of the virus, which goes through peaks and valleys worldwide in a two- to three-year cycle.
“It’s notable that of the 18 multi-state outbreaks in 2007, Salmonella was in 10 of 18, and this doesn’t include the peanut butter we heard about later on,” said Purnendu C. Vasavada, PhD, professor of food science at the University of Wisconsin-River Falls. “Salmonella is a very hard organism to deal with. The problem is, there are over 2,500 strains and a very wide variety of potential food sources for it to be found in.”