Infection
An Infection is a disease inflicted by certain zombie bites that are particularly deep. If untreated, the infection will eventually kill you. You can clean the wound with a first aid, or take antibiotics if the infection progresses.
Bite wound
Zombie bites that hit and do significant damage can leave bite wounds that feel "really deep...". Such a wound is a serious threat; though you've got about 6 hours (3600 turns) after being bitten, you should pay attention and take care of the problem ASAP as it gets tougher to treat over time.
For the first two hours (2400 turns) you'll occasionally be warned about it ("Your bite wound really hurts.").
After 4 hours (1200 turns) the wound will cause you pain (up to 20 points), making sleeping very difficult ("Your bite wound feels swollen and painful.") and reducing your dexterity by one.
After 6 hours untreated, the bite wound will probably become infected. A healthy diet, along with relevant traits such as Infection Resistant, can help your system repel the infection on its own. However, that'll leave you in a weakened "Recovery" state for a while.
You can clean a bite wound with a first aid kit, disinfect it, or painfully cauterize it with a hotplate or soldering iron. Once the infection's fully developed, cauterizing and cleaning won't help as it's spread into your body. You can also cauterize wounds with a knife if you've got fire nearby (an adequately filled lighter will do), but cauterization is not guaranteed to prevent the infection, and might actually make the situation worse.
Cauterizing a wound successfully causes a mildly painful "recovering wound" status.
Infected wound
Infections might develop when a bite wound isn't addressed within 6 hours. This disease will last for 24 hours.
After getting this disease, your dexterity will be reduced by one point and your speed by 80 points ("Your bite wound feels infected").
After 6 hours, your strength and dexterity will decrease one point. You'll also suffer from severe pain (up to 40 points), making sleeping very difficult ("Your infected wound is incredibly painful.").
After 12 hours, your strength and dexterity will be reduced for another two points. You'll also occasionally vomit and suffer from severe pain (up to 60 points), making sleeping very difficult ("You feel feverish and nauseous, your wound has begun to turn green.").
After 18 hours, your strength and dexterity will be reduced for another two points. You'll also occasionally vomit, pass out and suffer from severe pain (up to 30 points), making sleeping nearly impossible.
24 hours after the infection (30 hours including the bite wound) you will die ("You succumb to the infection.").
You can cure the infected wound by taking antibiotics, royal jelly or cleaning it with a first aid kit. This will give you the "recovering" status ("Recovering From Infection") with duration equal to 4 times the time spent with infected wound.
An infection can randomly heal on its own. A starting survivor has roughly a 15% chance of surviving an untreated infection. This chance is significantly higher with the Infection resistant trait.
This disease can also be part of an NPC mission, where you'll be asked to bring antibiotics back.
Recovering from infection
You will slowly recover your strength and dexterity points while in this state. This state will last until they both are back to their original points.