Far-ultra-violet rays

"I call this meeting of Imperial Kagomine Non-Commissioned Armed Service Officers to order. Most of you are medical officers, priests, lifeguards, sorcerers, and those that aren't are specialists in helping servicemembers through hard times through motivational techniques, support, psychology, and propaganda." Spoke Amarat, uncomfortable in his green-and-fiery-orange uniform.
"We have been called together today by LGOR-04 T-Cell Bjork Candless to discuss a potential breakthrough in preventing transmission of the Slate Plague , formerly known as the Green Plague , but which threatens to be called by the name of all the primary cold colours, successively, if we do not stop it, as it mutates, and targets a different member of our species, each time."
"Thank you, Valour-keeper." She paused, such a reservoir of authority was not normally a member of the group of non-coms, she felt distinctly uncomfortable, as if everywhere he walked, a spotlight followed, and journalists, and court clerks. But then, as Valour-Keeper, he was responsible for the clerks, and ushers, and judges, and ... The Apihmei of Kagomei had more authority, but less to do with the day to day running of the kingdom. She looked at the crowd. What's with all the Emerald Ribbons? she thought to herself, she was stunned, no less than five solid emerald-green ribbons in just the first row, let alone the Valour-Keeper's four ribbons of emerald so pure they matched his royally-born eyes. "I'm sorry..." She stammered. "I'm just a bit overwhelmed, this isn't the research community in Lavali, far too many heroes' ribbons..." She turned on the projector, sharing her Jade Bank 's screen over the wall behind her. "As you may know, most things only live once. The slate plague virus is no exception, but it tries to fool us into thinking it's dead, then springs back to apparent life. Living in environmental reservoirs that are asymptomatic, like sheltered bodies of water, unaffected plants, and the like.
We've found that exposing such to far, that is short-wavelength, ultra-violet radiation kills the virus, decomposing them, and bursting their protein protective capsules.