"From your description, it's basically certain Phenilos was contaminated by Nurgle's power."
Cran's voice came over the comms channel, carrying an almost shameful calm and rationality. "Its power can't affect you. I can guarantee that. But the people of Phenilos are another matter. The ship is scanning now. If we confirm there are no survivors, I'll cleanse the entire planet immediately—at the very least, I'll scour the whole surface once."
"Understood, my lord," Ezekiel replied.
He had no real objection to that. When it came to Nurgle's plagues, the Empire was surprisingly unanimous. Whether you were an Adeptus Mechanicus priest, an Ecclesiarchy cleric, or some high lord of the Departmento Munitorum, anyone with a functioning mind knew there was only one official cure for Nurgle's plagues.
Treat an infection, one bullet at a time. Treat a Nurgle infection, one Exterminatus at a time. Many scholars who knew forbidden truths had objected to this, even shouting that those poor infected deserved a little hope. Of course, in the end, they all learned to shut up.
No one threatened them. The Departmento Munitorum merely showed them the truth.
Khorne's daemon armies could still be held back by shells and human waves. Tzeentch's schemes, in the past, targeted only the wise. Slaanesh's followers pursued pleasure, and were therefore especially conspicuous. All of them could be stopped to a certain extent, destroyed to a certain extent.
But Nurgle's plagues could not.
A virus used humans as its carrier. If you wanted to eradicate the virus, you could only eradicate the humans on that planet along with it. There was no other way. If you did not, you would be watching the virus spread with your eyes wide open.
There were records of this. A plague could spread to many planets in a short span