The Centers for Disease Control and Prevention released new statistics on foodborne illness outbreaks today in its Morbidity and Mortality Weekly Report.
The most recent numbers, which were obtained from epidemiologic investigations conducted in 2007, show that for outbreaks in which a specific pathogen causing illness was identified, norovirus was the most commonly reported cause of foodborne illness, followed by Salmonella.
Epidemiologists reported 1,097 outbreaks in the 50 states, District of Columbia, and Puerto Rico, which resulted in 21,244 cases of foodborne illness and 18 deaths. The 18 deaths were caused by various pathogens: 5 were attributed to Salmonella infection, 3 to Listeria monocytogenes, 2 to E. coli O157:H7, 1 to Clostridium botulinum–the pathogen that causes botulism, 2 to norovirus, and 1 to a mushroom toxin. Four of the deaths could not be attributed to a specific pathogen.
Outbreak investigators were able to trace 235 of the 1,097 outbreaks to a single food commodity, finding that poultry, beef, and leafy vegetables were the most commonly detected causes of illness. According to the report, of the 17 food commodities–finfish, crustaceans, mollusks, dairy, eggs, beef, game, pork, poultry, grains-beans, oils-sugars, fruits-nuts, fungi, leafy vegetables, root vegetables, sprouts, and vegetables from a vine or stalk–the commodities most commonly implicated in outbreaks were finfish, poultry, and beef.
Epidemiologists were unable to determine the pathogen causing illness in 363 of the reported outbreaks, and in 71 percent of those instances, the food causing illness was not determined. In instances when pathogen-commodity pairs were identified, the pathogen-commodity pairs responsible for the most outbreak-related illnesses were norovirus in leafy vegetables (315 illnesses), E. coli O157:H7 in beef (298 illnesses), and Clostridium perfringens in poultry (281 illnesses).
Delayed reporting to the health department, too many food items consumed by people reporting illness to identify a single food as the source of illness, and the lack of human or food sample test results were the most common reasons reported for not identifying a particular pathogen or food responsible for illness.
Overall, norovirus caused 193 foodborne illness outbreaks, Salmonella caused 136, and Shiga toxin-producing E. coli caused 40–39 of which were caused by E. coli O157:H7.
Multi-State Outbreak Figures
Among the 18 multistate foodborne illness outbreaks reported in 2007, 10 were attributed to Salmonella, six to E. coli O157:H7, one to Clostridium botulinum, and one to norovirus.
Salmonella: Foods associated with multistate Salmonella outbreaks included commercially-processed frozen pot pies (401 illnesses, three deaths), commercially-processed vegetable snacks (87 illnesses), eggs (81 illnesses), spinach/lettuce (76 illnesses), beefsteak tomatoes (65 illnesses), raw tuna (44 illnesses), ground beef (43 illnesses), cheese (20 illnesses), alfalfa sprouts (15 illnesses), and raw fresh basil (11 illnesses).
E. coli: Of the six multistate outbreaks of E. coli O157:H7 infection–including the Cargill E. coli outbreak that resulted in Stephanie Smith’s illness–the vehicle for five was ground beef (117 illnesses) and the vehicle for one was commercially processed frozen pepperoni pizzas (27 illnesses).
Clostridium botulinum: The vehicle for the C. botulinum toxin outbreak (eight illnesses) was commercially canned hotdog chili sauce.
Norovirus: The one multistate outbreak caused by norovirus was associated with raw oysters (40 illnesses).
Two of the three largest reported outbreaks in 2007 were caused by Salmonella. The vehicles were hummus (802 illnesses) and commercially processed frozen pot pies (401 illnesses and three deaths).