Epidemic at Motherbase

So I'm at the point that the epidemic has broken out at mother base (Mission 25).

I just went ahead and looked up how to fix this damn thing (quarantine Kikongo speakers and complete the next 4 missions ASAP) - but I'm unclear on a few points. I painstakingly went through all my 900+ staff and quarantined all the Kikongo speakers I could find (which was somewhere in the region of 300+) but some of them can't be quarantined because they are out on combat missions. Do I need to worry about them when they come back? Some of them are on a online deployment - so they are going to come back when I'm not playing. And is there any easier way to find the Kikongo speakers and make sure I didn't miss any than scrolling through 900+ people and squinting at their languages?

Also, how does the epidemic affect the FOB stuff? And the PF league stuff? Is that basically all screwed until I power through the next story missions?

And what about new people that might be recruited in the meantime? Should I not Fulton anybody because they might be infected? What about recruits you get as rewards? Should I not accept those rewards until after mission 29?

The epidemic will make your soldiers sick, and some of them might die. Anybody on your base who meets the criteria is vulnerable, so yes: anybody who comes back from a mission may get sick, and anybody new you Fulton may get sick.

Soldiers who are sick don't perform their typical duties, so they will negatively impact your FOB-related ratings and how you perform in the automated PF rank-related battles, and the overall rating of your various departments. However, soldiers who are quarantined also don't participate, so quarantining the appropriate subset of your 900+ staff will still negatively impact you. It will also be exceedingly tedious to do, as you have discovered: there's no better way than scrolling through the list looking at their stats.

Your best bet is likely to ignore the quarantining aspect and just power through the story until the epidemic is no longer an issue. It will likely be more fun then trying to stay on top of every new soldier you Fulton in and everybody who comes back from a mission. The only thing you'll miss (as far as I recall) is some dialog on the codec about how you've discovered what the common factor in all the sick cases is. The dialog is really vague, it basically consists of Miller saying something like "Boss... could that really be the cause...?" You won't be missing much.