This happened to me once, but not with sushi.
I used to buy stuffed vine leaves from Lidl on a semi-regular basis (the sort that were on the deli/refrigerator part, rather than tinned).
I got home from shopping once, thinking I'd bought four packets but there were actually five.
I thought I'd just picked 5 up by mistake.
Nope.
I ate some that had been in the car, festering, for lord knows how long, from a previous shopping trip. It was summer too!
I was soooo ill!
I won't go into full details but let's just say it was both ends and my legs and 'other areas' were burnt from the liquid that exited my body.. And I felt dizzy as hell, and one of my bum cheeks and my leg went numb. NHS 111 told me to come straight in. The problem was, the following day was my grandmother's funereal. I had to set off first thing, I wasn't going to miss it. Luckily, very luckily! The numbness had gone by that day. I had to stop at every services on the way down to throw up from both ends. And I was dizzy and felt sick all day. My Dad, helpful as always bought me a double vodka and red bull at the wake, thinking it would perk me up I think it did to be fair but I was in bed as soon as I got the opportunity and couldn't eat anything for a couple of days.
But in short, I can see how this sort of incident happens.