I'm normally really good about taking care with food but had family over yesterday and made a cake and for some reason drizzled some Belgian chocolate sauce we had in the cupboard over the top without thinking. Just realised today it's supposed to be refrigerated after opening and used within 4 weeks, and I opened it at the end of November (know exactly when due to the thing I needed it for) so it's been opened and in the cupboard since then.
I know food poisoning normally kicks in within a day and we ate the cake after lunch yesterday but have read campylobacter takes 2-5 days and is really serious for older people (2 of the cake eaters are in their 70s). Is there any way to find out if I've given us all food poisoning and it hasn't hit yet, especially as then I'll keep a closer eye on the older people, and anything we can do to head it off or relieve symptoms if so?