Sterilize your water, wash your hands regularly, keep away from rats and people (the usual vector) i.e. places such as restaurants and hospitals, keep fit and healthy and well nourished and if all else fails there is always the catchy great plague song

The Four Horsemen of the Apocalypse don't usually turn up at the same time they appear sequentially after those that precede them attempt to do their worst. Keep the Grim Reaper away. Don't eat the Salmon Mousse. Try not to be poor (the greatest actuary to premature death).