Ill after visiting Fulham

Trigger warning: description of illness

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Hey all, just wondering if anyone has had anything similar and can point out the issue. I lived in London for a year a while back and was fine. I no longer live in London.

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I've visited a friend in Fulham 3 times now, and 2 of those times have led to me having a splitting headache, vomiting, minor diarrhoea, shaking, fevers, ending up on the floor not able to stand without collapsing etc, but then 95% recovered by the next morning. I've never had that horrible combination outside of these 2 times.

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The first time they cooked, and since they were fine they reckoned I must have food poisoning from before I came over, but I'd just had Shreddies so it probably wasn't that. The 2nd time I was fine, they made bbq. The 3rd time was yesterday, June 21st, and we got Wendy's. So I don't think it was the food, but could it be the water?

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Has anyone had visitors who got really ill in London? I'd assume they were fine on the same water because their bodies are used to it. Or maybe something else they're used to?