As Triathletes we live our life pushing limits. It's what we do. The downside to this lifestyle is that we often find ourselves on a razor thin line between top fitness and illness. Here are some thoughts on how to handle training when illness hits.
First, consult with your medical team. Be honest and make sure they know the extent of your training activities. Most people have no idea how much we train as Triathletes and that includes your Dr.
Second, this is tough to hear but do what your med team tells you to do, including taking some time off.
Third, if you are down for any length of time let it go. Don't beat yourself up about workouts missed and most importantly do not try to "make up" for lost time when you do feel better.
Next, make sure that you keep your fluid intake high and eat a healthy diet.
Finally, when you are cleared to resume your life consider a slow sensible and measured comeback. For example if your first bike ride back is scheduled for a 6 hour "suffer-fest" consider cutting it back to 2-3 hrs of easy, endurance riding. Take this approach with your first three or four workouts back and you will be back up to speed (pun intended) in no time.