If that's the case, then there's no excuse to turn up to work unless it's absolutely necessary. Hell, it seems that they give employees plenty of reasons and incentives to call off sick if they're not well. Headaches, upset stomachs, maybe a minor cold, I can understand. But if you've got a bad cold or the flu or worse, why risk it and making others sick at work? And as you mentioned, any disease going around could close the plant until at least everything is disinfected. Very counter productive I say.
That's why when I'm really sick, I usually call off work. Everyone congregates around my area where I work, and there's no reason, especially in seasons where people get ill anyways, for me to risk making things worse for myself or others.