Project Zomboid Infection Mechanics in Build 42
Knox virus versus bacterial wounds: how to read the Health panel before you waste the last antibiotics.
The search “Project Zomboid infection” usually means one of two deaths. Either a zombie bite started the Knox virus and the run is already a countdown, or a dirty wound went bacterial and you still have time. Build 42.20.4 did not rewrite that split. This page is the mechanics chapter: transmission sandbox, Health-panel language, what antibiotics actually do, and how to stop treating food poisoning like a bite. Symptom timing and herbal tables live on Fever and Illness. Bandage technique lives on Medical and First Aid.
Project Zomboid remains Early Access. After a hotfix, hover the wound tooltip in your client. Wiki text is directional.
Two infections, one red moodle stack
Knox infection is the zombie pathogen. On default Apocalypse it arrives through a zombie bite (and, depending on sandbox, through blood or saliva on other wounds). Vanilla has no cure. Antibiotics, disinfectant, and Lemongrass do not reverse it. The Health panel tracks the bite. Sickness moodles climb toward fever. The character dies and, unless sandbox says otherwise, rises.
Wound infection is bacterial. It shows on a scratch, laceration, or bite as an Infected wound state. Dirty bandages, unwashed blood, and skipped disinfectant make it worse. Antibiotics and clean dressings fight this track. In-game tooltips still say antibiotics cannot prevent zombification. That sentence is the whole argument.
If you only remember one rule: clean the wound, then ask whether the wound was a bite. Bite first, story second.
How to read the Health panel
Open Health after every fight, not after the first Queasy icon.
- Find the body part. Bite, scratch, and laceration are different injuries.
- Note Infected on the wound. That flag is bacterial unless the bite already started Knox.
- Note other moodles: Noxious Smell (corpses), Wet or Hypothermia, Has a Cold, Hungry/Thirsty. They explain fever that is not Knox.
- If the last contact was a zombie mouth on skin, treat the run as infected until proven otherwise. Do not spend the group’s last penicillin “just in case” on a cold.
Fever and Illness walks food poisoning, corpse smell, and flu. Come back here when the question is “am I turning?”
Sandbox transmission settings
The Zombie Lore → Transmission dropdown decides how unfair the county is:
- Saliva only (common Apocalypse default): bites are the Knox gate. Scratches and glass cuts are still dangerous for bacterial infection and bleeding, not automatic zombification.
- Blood + saliva: non-bite zombie wounds can carry Knox. Glass, crawler grabs, and bloody clothes matter more. Hygiene from Wash Clothes is survival, not cosmetics.
- Everyone is infected: Knox is already in the blood. Bites still hurt. Death still reanimates. The “did I get bit?” panic becomes “how do I die without wiping the base.”
Challenge presets and Game Modes can tighten these rules. Extinction and some Challenge Modes are not Apocalypse. Read the preset before you quote a Reddit survival story.
Bite, scratch, laceration
Bite: highest Knox risk on saliva-only. Highest bacterial load even when Knox is off. Bandage and disinfect immediately. Then decide whether this character still has a future. On default Apocalypse, plan the will: drop the bag, call the location, walk away from the generator if you are the only one who knows the fuel math.
Scratch: often survivable. Disinfect, clean bandage, watch the Infected flag. Clothing from Clothing and Weather and Tailoring padding reduce how often this happens. It is not a bite.
Laceration: deeper bleed, longer first-aid, more chance the wound goes Infected if you leave a dirty rag on it. Still not automatically Knox unless Blood + saliva is on or the tooltip says bite.
Learn spacing in Combat Basics so you take fewer of all three. Zombie Types explains why crawlers and sprinters create different wound shapes.
Antibiotics, disinfectant, and folklore
Disinfectant / alcohol wipes / bourbon: clean the wound and cloth. They lower bacterial infection. They do not delete Knox.
Antibiotics: wound-infection drugs. Use them when the Health panel shows an infected wound, not because you feel Queasy after rotten cabbage. Wasting them on Knox or food poisoning is how month-two bases die of a later scratch.
Lemongrass / mallow: symptom managers. See Fever and Illness. Not a bite kit.
Washing blood off skin and clothes: reduces ordinary infection risk and corpse-sickness exposure. It is not a vaccine. Pair with Wash Clothes.
Timeline thinking (without fake hour counts)
Knox on a default bite is a day-scale problem, not a “pop a pill in ten minutes” problem. You get a window to reach base, write a note, and hand off the car keys. You do not get a reliable vanilla reset. Wound infection is slower and answers to hygiene. If fever appears with no bite on the panel, hunt food, corpses, cold, and dirty bandages before you eulogize the character.
Build 42.20.x hotfixes through 42.20.4 did not advertise a new Knox cure. If a patch note ever does, this page will change. Until then, treat YouTube “I survived a bite with 40 antibiotics” clips as sandbox or luck, not a protocol.
Co-op rules that keep the season alive
- Call bite versus scratch on voice the second the animation ends. Vague “I’m hurt” wastes antibiotics.
- Park bitten players away from the only staircase if they might turn overnight. Sleep and Rest and house layout from Safehouse matter.
- Keep a shared medical crate. The bitten player should not hoard the last bottle “for later.”
- On Everyone Is Infected, agree in advance whether a death is a respawn at base or a season pause. Sandbox Settings should be screenshotted on day zero.
Prevention that actually works
Fight in doorways. Shove before you swing. Wear long sleeves you can still run in. Wash blood before you sleep. Replace dirty bandages on a timer. Do not loot Louisville in a tank top because the summer heat moodle is annoying—see Louisville and Winter Survival for the opposite season’s trap.
Infection mechanics are a reading skill. The Health panel tells the truth. The sickness moodle only says you feel bad.
Frequently Asked Questions
Quick answers to the most common questions.
Can you survive a zombie bite in Project Zomboid?
On default Apocalypse saliva transmission, vanilla has no Knox cure. Bandage and disinfect anyway for the bacterial wound. Treat the bite as the end of that character unless your sandbox says otherwise.
Do antibiotics stop the zombie virus?
No. Tooltips state they cannot prevent zombification. They treat bacterial wound infection. Use them when the Health panel shows an infected wound, not as a bite antidote.
What is the difference between Knox infection and wound infection?
Knox is the zombie pathogen, usually from a bite, with no vanilla cure. Wound infection is bacterial, flagged on the injury, and answers to disinfectant, clean bandages, and antibiotics. See also Fever and Illness.
Does Blood and Saliva make scratches lethal?
It can carry Knox through non-bite zombie wounds. Scratches also still risk bacterial infection on any setting. Check Transmission in Sandbox Settings before you copy a build from a streamer.
I have fever but no bite. Am I infected?
Often no. Food poisoning, corpse smell, cold, and dirty wounds cause fever without Knox. Open Health, list the last day’s risks, and use Fever and Illness before you abandon the save.