That plague WAS a pandemic until our science advisor developed a cure, it seems.
It's under control. Doesn't mean that there's a cure, just that it's not spreading."I'm not asking for your budget, Minister! And it's hardly something as simple as painkillers. The Rachni Plague might be under control, but it's a clear indication that we need to update our medical infrastructure! If we have people dying of disease, your navy will wither!"
And the fact that a plague managed to break out - named after the Rachni, no less (not sure if that's a misnomer or not) - in a space setting like Mass Effect is cause for concern.
Plus:
That's 4% of a population of 5,000,000,000."Madame Minister. I have compiled a report for you on what remains of the Rachni Plague. Currently, fewer than 4% of the population exhibit symptoms, and a mere 0.00000032% are expected to encounter lethal complications.
Which means 200,000,000 people were infected. Possibly across multiple races.
That is definite cause for concern.