June 06, 2011
Frightening food
Food scares are in the air (in the pot?) right now, but what should we be rationally worried about in terms of outbreaks of food-borne diseases?
CDC has a Foodborne Outbreak Online Database that contains cases from the last two decades. These are cases serious enough that somebody reported them to the CDC. They cover everything from bad sausages to salt and muktuk (fermented beaver tail). Writing a parser for the data in Matlab, I got the following results:
Most number of people affected by the food (i.e. what is most likely to get you if you eat an average diet):
| Affected | # outbreaks | Mean size | Food |
| 56769 | 1952 | 29.082480 | - |
| 2760 | 55 | 50.181818 | multiple foods |
| 2285 | 17 | 134.411765 | tomato, unspecified |
| 1747 | 3 | 582.333333 | other milk, pasteurized |
| 1536 | 17 | 90.352941 | salsa, unspecified |
| 1535 | 1 | 1535.000000 | peppers, jalapeno; tomato, unspecified; peppers, serrano |
| 1397 | 6 | 232.833333 | watermelon |
| 1332 | 28 | 47.571429 | potato salad |
| 1273 | 32 | 39.781250 | pork, BBQ |
| 1016 | 19 | 53.473684 | cake, unspecified |
Many outbreaks are never traced, or due to multiple foods. But otherwise it is clear that it is the veggies that are risky, besides the somewhat obvious milk and BBQ pork. Badly washed vegetables or spicy salsas that hide off tastes are clearly worth watching out for. And while the cake might not be a lie, it can be slightly risky.
What foods cause the most alarms? These would be the foods that are easy to get illness from, but the outbreaks are small:
| Affected | # outbreaks | Mean size | Food |
| 56769 | 1952 | 29.082480 | - |
| 210 | 56 | 3.750000 | fish, mahi mahi |
| 2760 | 55 | 50.181818 | multiple foods |
| 210 | 49 | 4.285714 | fish, ahi |
| 940 | 41 | 22.926829 | oysters, raw |
| 934 | 40 | 23.350000 | lettuce-based salads unspecified |
| 219 | 39 | 5.615385 | tuna, unspecified |
| 320 | 36 | 8.888889 | ground beef, hamburger |
| 936 | 35 | 26.742857 | ground beef, unspecified |
| 548 | 33 | 16.606061 | chicken, unspecified |
Now seafood and meats jump up, although those salads still cause trouble. The reason for the mahi-mahi is likely ciguatera - those dinoflagellates can produce some pretty impressive poisons.
What foods produce the biggest outbreaks?
| Affected | # outbreaks | Mean size | Food |
| 1535 | 1 | 1535.000000 | peppers, jalapeno; tomato, unspecified; peppers, serrano |
| 950 | 1 | 950.000000 | gravy, beef; roast beef, unspecified; potato, mashed |
| 716 | 1 | 716.000000 | Peanut Butter; Peanut Paste |
| 715 | 1 | 715.000000 | peanut butter |
| 1747 | 3 | 582.333333 | other milk, pasteurized |
| 552 | 1 | 552.000000 | tuna salad; salad bar |
| 517 | 1 | 517.000000 | chicken, baked; green pea salad |
| 927 | 2 | 463.500000 | corn, unspecified |
| 333 | 1 | 333.000000 | pasta salad; potato salad; vegetable-based salads unspecified |
| 300 | 1 | 300.000000 | picadilla |
...
The problem here is that many of these are single outbreaks - that pepper outbreak affected 1535 people. So to be on the safe side, lets look at the biggest average size of outbreaks where there has been more than 2:
| Affected | # outbreaks | Mean size | Food |
| 1747 | 3 | 582.333333 | other milk, pasteurized |
| 830 | 3 | 276.666667 | hummus |
| 999 | 4 | 249.750000 | macaroni salad; potato salad |
| 1397 | 6 | 232.833333 | watermelon |
| 650 | 3 | 216.666667 | roma tomato |
| 993 | 5 | 198.600000 | green onion/scallion |
| 675 | 4 | 168.750000 | basil, unspecified |
| 653 | 4 | 163.250000 | orange juice, unpasteurized |
| 413 | 3 | 137.666667 | pot pie |
| 2285 | 17 | 134.411765 | tomato, unspecified |
The vegetables strike again. This is also where biosecurity has to work hardest: presumably these are the easiest ways of distributing food-borne pathogens. The dairy industry is recognized, but how much protection does our watermelons have? (the problem with watermelons and several of the others is likely that they have an often unwashed surface that people touch with while eating, and then they get the pathogens in their mouths)
In total, 161284 people were affected in 5153 outbreaks. 181 died, 7803 were hospitalized.
And people worry about genetically modified food! They should worry far more about ordinary dirt and the natural, very organic pathogens that live there.
(Some caveats: the same foodstuff might occur in several food descriptions, making exact analysis a bit tougher than what I want to do a Monday evening. I make no claims to know what I am doing. Here is the processed file, sorted by affected people: Download file )
Posted by Anders3 at June 6, 2011 09:16 PM