Anno 2070 lets you know when something goes wrong by posting a message in the alert queue and sticking a floating icon over the troubled area. For instance, when citizens get sick, a red cross hovers over the afflicted building. If a hospital is in range, it will dispatch an ambulance hovercar thingie and all will be well soon enough. If a hospital isn’t in range, well, you should probably build one or suffer the population reduction.
Furthermore, Anno 2070 will almost always reward you for taking a closer look. The above screenshot is what you’ll see if you zoom in and look at a building under one of those hovering red crosses. You can see officials in hazmat suits have posted barricades around the afflicted buildings while they wait on an ambulance hovercar. Good work, guys. So why has the sickness spread to three buildings? Let’s get there sooner next time, okay?