I was 46 when I got my first D&V illness, which later turned out to be campylobacter.
Until that point, I'd thought that diarrhoea was just having a runny poo. No-one had told me how agonising the stomach cramps could be, how total the loss of control, how high the fever could get, how you could be so weak you couldn't stand and how it could make you welcome the prospect of death, because you felt so shit that death was preferable.
In the end, I started self-medicating with codeine, which helped. I figured that if it made you constipated, it might stop the constant eruptions. My GP found this amusing, for some reason.
He gave me this envelope with the container for a stool sample so it could be tested. When I got it home and opened it, I was astonished to see this small vial, less than an inch in diameter. Even though I was shitting through the eye of a needle, I was mystified as to how I was supposed to poo into this tiny tube and said as much to my ex.
I felt very foolish when I opened it and found the little spatula thingy inside. 
Mine was caused by a dodgy meal (boeuf bourguignon) in a pub.