Med Lab / Plague working correctly?

[Questor]

I'm not sure if this is a bug or not. I had a Med Lab II in a system but a plague level 1 still broke out. It was cured the next turn but I still lost 12M population and had an angry colony to deal with. Is this the way they are suppose to work or should the plague have been prevented in the first place. The Med Lab description states the it will "prevent" a plague of equal or lower level, IIRC.

Also does anyone know if the AI will handle biological warfare? In my current game I have been plague bombing my enemies colonies. The AI doesn't seem to be doing anything about. Will the AI make medical ships to combat this?

Thanks,

Questor