Views / Citizen Scientist

Can you get food poisoning twice in a row, from the same food?

A pressing science question: Are your leftovers out to kill you?

Is this a deadly weapon?


Is this a deadly weapon?

Can you get food poisoning twice in a short period if you eat the exact same food again in the form of leftovers?
– G. B., Toronto

Okay, I confess. This issue is personal to me, and I sent this question to myself because I wanted an excuse to research it. A few weeks ago, the universe punished me for making a joke in this column about eating raw cookie dough. I came down with a miserable stomach bug.

I hadn’t been around any sick people or eaten anything suspect that I could recall. The cause was a mystery, until two weeks later, when I had a flash of insight: I’d eaten cookie dough that contained raw eggs, a common source of salmonella bacteria, the night before I became ill.

Unfortunately, I had this brainwave while there was a wooden spoon of raw muffin batter in my mouth. It also contained raw eggs, from the very same carton. Uh-oh?

I instantly felt extremely sick, and continued to for 48 hours.  Was I just anxious, or is it possible I had salmonella twice? I asked Dr. Bruce Vallance, the stomach-bug guru at B.C. Children’s Hospital.

It depends on the timing and the germ, but if you’re exposed again after you recover, you’ll likely get sick again, Vallance said in an email, adding it’s “very difficult” to develop complete immunity against germs that attack the gut.

However, any barf-inducing bug you catch (salmonella, norovirus, whatever) has a unique genetic signature your body learns to recognize and fight off. 

If you get food poisoning, then encounter the exact same strain of the exact same bug a week or two later, you may have some resistance. You’ll probably get sick, but not as badly as the first time around, Vallance explained. That may have been what happened with me and the cookie dough (Lesson. Learned).

If I was unlucky enough to catch a different strain though, I would be just as susceptible as anyone else.  

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