Dave: over the past decade or so a lot of Americans have been sold variable-rate mortgages "because interest rates are only going to go down".

Martyn: forget cholera -- cholera is trivially treatable if you have a source of heat for boiling water, and a supply of sugar and salt. (It kills through dehydration; the treatment is simply to make the victim drink lots of isotonic fluids until their gut flushes itself clean -- or, if they can't drink, to hook them up to an i/v drip.)

The real forthcoming medical threat is H5N1, which from some reports in Malaysia may have already hybridized into a human-transmissible form and be about to go epidemic. Ick.