Something else to worry about... "Fifth Disease" - terrifying label, like something out of the X-files. Makes you think about the Fifth Horsdeman of the Apocalypse or something on the same lines. <>

Do other diseases have numbers? Like species assimilated byn the Borg in Star Treck? But I'dhave thought by this time we'd have got to rather higher numbers than that for any new arrival.

You could work it into a maligerer's version of "The 12 days of Christmas, in place of Five Gold Rings."

"On the First Day of Illness my doctor said to me - a slight case of helico-b..."