I had a friend who got bitten by an insect on the Thames**. Something on the insect or on her arm got into her bloodstream, and 2 days later she was admitted to hospital and put on an antibiotic drip. Lots of people get cuts or bites around there, very few get hospitalised, so I assume her immune system was compromised in some way. I'd assume the same with
@surfdude - rather than a reaction to the sting itself.
Also recently, I flew across the world to <very sad event>. With the combination of jet lag and grief, my immunity went down the toilet, and I ended up with cellulitis for the only time in my life, that took 3 courses of antibiotics to clear.
@surfdude, you'll almost certainly be fine if you do the ride. There's just a small chance of a very bad outcome indeed.
**downstream of Mogden, so effectively an open sewer.