How to identify infected staff members and quarantine them
Close to halfway through The Phantom Pain, an outbreak will spread throughout Mother Base. That infection, as you’ll soon find out, is the Vocal Chord Parasite. The game keeps telling you to isolate the infected even though you’re not really told how to detect the symptoms.
There are two ways you can go about solving this. The first is to continue playing main missions. At some not-too-far-off point, you’ll come across a character that will reveal to you how you can identify the symptoms. A couple of missions after that, a cure will be introduced as part of the story.
Doing things this way will lead to the death of some of your staff. You don’t know who, and some of them could be among the high-skill ones. Which is why it’s preferable to follow the second course of action.
Once the first soldier gets infected, Miller will establish a quarantine platform and move the infected over. Go to your staff management screen, navigate to that platform and note the language spoken by the infected. Whatever that language is, you must quarantine anyone that speaks it as soon as possible.
Sorting through staff management can be a pain, depending on the number of recruits you have, but it’s better than losing them. Just identify them, select them (you can select multiples and move all at once), and quarantine them. Once the story moves forward and you devise a cure, everything will return to normal.