Norovirus, ah, I love you. Our annual visitor in London. If you have kids, you get Noro, plain and simple.
It's 1,000 x more infectious than flu. Hand sanitisers don't kill it. It spreads by touch (and aerosol / bodily fluids etc).
It's foul, and has nearly caused me the worst moment of my public life. I was spared by 0.5 seconds, and I'm not kidding.
Strict quarantine and plenty of bleach, that'd do it. Mind you, you're infectious before and after the expulsion phase - that's just the dramatic bit.
Gorgeous little organism - rates highly on my chart of well evolved things, in DNA survival terms.
I believe it comes from the oyster beds. Shows up in Autumn, when the UK starts eating oysters after the summer break. Peaks in winter, when it spreads around, then dies off in spring.