Every so often a city may have an event happen. Such as disease outbreaks or vermin infestations.
To cure a city of disease, antitoxins are necessary. Each city cycle the city will use some of the antitoxin in storage. The lower the TL of the antitoxins, the more is needed, depending on the "TL" of the disease. The city will show in the city reports how many antitoxins are required to cure the disease.
Passengers loaded from a diseased city will carry the disease, giving the potential risk of spreading the disease to other cities.
For details on how avatars are effected by disease, see the Health#Afflictions page.
Infestations are caused by vermin. The vermin will consume large amounts of food each city cycle.
Pharmaceuticals are needed to kill them off. If your city has an infestation, the city reports will tell you how many pharmaceuticals will be needed to kill the infestation and what TL it needs to be.
Should you lack of the required Pharmaceuticals, infestation can be dealt with alternatively by starving off the city. This is dangerous since it will start to kill citizens too, if carried on too long it can lead to decay.
All Pharmaceuticals will kill all infestations, but same or higher TL drugs will clear up the infestation faster and more efficiently.