Norovirus was the most common confirmed cause of food poisoning in 2007. Among foods involved in outbreaks, poultry was most commonly cited, according to a report from the US Centers for Disease Control and Prevention (CDC).
According to a release from the The Center for Infectious Disease Research and Policy (CIDRAP), the latest complete data indicates that 1,097 foodborne outbreaks, representing 21,244 cases and 18 deaths, were reported for 2007, according to the CDC in todayâ€™s issue of Morbidity and Mortality Weekly Report (MMWR). A total of 497 outbreaks were clearly traced to a single pathogen, and norovirus was blamed for 193â€”39 percentâ€”of those, including 47 percent of the total cases, the report says. Salmonella was the second leading cause: 136â€”27 percentâ€”outbreaks, including 27 percent of the cases.
The report shows that 235 outbreaks involving 4,119 illnesses were linked to a single food commodity: Poultry, the most common culprit accounting for 691 cases (17 percent), followed by beef, with 667 cases (16 percent), and leafy greens, with 590 cases (14 percent). The pathogen-and-food combinations blamed for the most illnesses were norovirus in leafy vegetables, 315 cases; Escherichia coli O157:H7 in beef, 298 cases; and Clostridium perfringens in poultry, 281 cases.
The single biggest outbreak involved 802 illnesses blamed on Salmonella-contaminated hummus. The second-largest outbreak involved 626 norovirus cases at a conference hotel in which several food items were suspected. The third largest was another Salmonella outbreak with 401 illnesses and 3 deaths tied to frozen potpies.
The CDC also identified the largest outbreaks associated with a single food commodity: 132 C perfringens infections and a chicken dish, a 128-case norovirus outbreak blamed on a leafy vegetable salad, 125 C perfringens cases blamed on chili beans, and 124 E coli O157:H7 cases linked to beef.
Norovirus outbreaks are believed to result mainly from contamination of food by infected workers who don’t properly wash their hands after using the toilet, the article notes. Also, foodborne outbreaksâ€”two or more similar illnesses related to eating the same foodâ€”make up only a small fraction of all foodborne disease cases reported each year, CIDRAP added, citing the report. For example, only 5.4 percent of all Salmonella cases identified in the CDC’s FoodNet surveillance system in 2007 were part of recognized outbreaks; many foodborne disease cases are never reported. An oft-quoted CDC estimate is that 76 million such cases occur each year, with most going undocumented.
In other observations, the article says that norovirus accounted for 97 percent of the virus-caused outbreaks and Salmonella accounted for 53 percent of all outbreaks traced to bacterial pathogens.