Mild cases of food poisoning are very common and most people attribute them to "stomach flu."
Some years ago I had a case of severe gastroenteritis that required emergency room treatment. I didn't know it was food poisoning until the hospital tested and diagnosed campylobacteriosis. After that, I was interviewed by the doctors about where and what I had eaten and who else had eaten it. The hospital reported it to the Illinois Dept. of Health, who also called to interview me.
The incubation period for this bacteria is a long one and it just so happened that during it I had only eaten packaged goods or shared meals except for one restaurant dinner in a Chicago suburb. When I spoke to the sanitarian for the suburb, it turned out he had coincidently inspected the day after I had my meal in the place -- they scored 50 out of 100 on their inspection and he had already ordered the staff to sanitation school (although he had not closed the restaurant).
My illness in this case was quite serious. I required intravenous fluids twice for dehydration and between the bacteria and the massive doses of antibiotics used for treatment, it was several months before I felt completely well again.
It took several years and a trip to the country involved before I felt comfortable eating that particular ethnic cuisine again, although it had been a favorite previously. (In fact, I contracted a mild case of travelers' upset on the trip, too, but it also reminded me of how much I enjoyed the cuisine.) I will never go back to the particular restaurant involved.
I guess I'm more careful in general, though probably
not as careful as I should be.