Infection

From RimWorld Wiki
Jump to navigation Jump to search

Overview

Infections can occur on most wounds. They are the fastest working illness in RimWorld, taking little more than a day to kill the victim if left untended. Animals can also contract infections, though at a reduced chance, which move just as fast.

Any cut, bite, burn or frostbite has a chance to become infected; blunt traumas (aka bruises) do not, nor can a pawn get an infection from losing a body part (i.e. a hand cannot become infected because of a lost finger). Once an infection sets in, it immediately becomes a life-or-death race between the infection's growing % vs. the patient's growing immunity %, first to a value of 1.00 (100%) "wins". If untreated, the patient loses this race in less than a day and a half, so any infection needs to be treated immediately and then twice a day (although, typically, you only get two chances at most). Any significant delay in any treatment hurts the odds of the patient surviving, or at least not requiring amputation (see below for full details).

General symptoms begin with a small amount of pain and partial loss of part function. Advanced symptoms progress to a small-to-moderate amount of pain, slight loss of consciousness and further loss of part efficiency. The final stages rapidly deteriorate to an excruciating amount of pain, some loss of breathing, a loss of consciousness, and acute part failure. Death follows not long after.

  • Prevention is the best treatment - a capable doctor and clean environment for treatment are critical to avoiding this deadly ailment before it happens.
  • If left untreated, infections kill (or destroy the limb) in a little over a day - untreated infections move fast!
  • Good treatment will slow the disease, giving the patient more time to build up an immunity and recover.

This disease is unique in that it only affects a specific body part, making infections curable by amputating the affected body part. It is not possible to amputate vital body parts.

  • The current progress of the infection (measured in %), and the patient's growing immunity against it, can be seen under the Health tab, by mouse-hovering over the specific infection. Remember - you want "Immunity" to reach 100% before the Infection does!

Mechanism

When a colonist has an infectable wound the game will count down randomly from 15,000 ticks (4.17 mins) to 45,000 ticks (12.5 mins). Once it reaches this timer it will decide if the wound will be infected.

The chance of a pawn getting an infection depends on the tend quality, wound type, room cleanliness at time of tending, and storyteller difficulty.

  • Treated wounds can still get infected at a reduced chance.
    • The chance multiplier is 85% at 0% tend quality, and linearly decreases to 5% at 100% tend quality.
  • Different wound types have different chances to get infected.
    • Bite, burn or frostbite wounds have a 25% chance.
    • Most other bleeding wounds have a 10% chance.
    • Bruises, cracks or missing parts cannot be infected.
  • Clean rooms with sterile tiles have a 32% chance multiplier. In contrast, a regular room without any dirt has 50%, and caravans and outdoors spaces have 100%.
  • Colonists are more likely to get wound infections at higher difficulties.

Animals have 20% of a colonist's chance to get an infection.

It is possible to have multiple infections simultaneously across different body parts. Each infection progresses at its own rate, while immunity against infections progresses at the same rate across the whole body. If the patient can become immune before the worst infection reaches 100%, that now-immune patient has beaten all their infections.

Stages

Minor - Severity: 0 - 0.32

  • +5% Pain

Major - Severity: 0.33 - 0.77

  • +8% Pain

Extreme (Initial) - Severity: 0.78 - 0.86

  • +12% Pain
  • -5% Consciousness

Extreme (Advanced) - Severity: 0.87 - 0.99

  • Loss of Consciousness (max 10%)
  • +85% Pain
  • -5% Breathing

Extreme (Fatal) - Severity: 1

  • Death

Progression

Two competing forces, the infection and the patient's immunity, progress separately toward 100% (a value of "1.00"); the first to 100% "wins" and the patient then immediately either dies or begins to quickly recover. The current status of both progressions can be viewed in the sick colonist's Health tab by mouse-hovering over the word "Infection".

If a patient is in good health and has decent conditions (see below), they gain immunity to any infection in just over 1 1/2 days, or more if there are any issues with their health/environment.

The bad news is that, if left untreated, infections can kill in less than 1 1/4 days - which is faster than immunity can be gained! So the goal is to treat the patient and slow the infection enough to give the patient time to gain immunity.

  • Until immunity is gained and without treatment, severity of the infection increases by +0.84 per day (or +.035 per hr.), progressing toward death at "1.00". Thus, if left untreated, infections can kill less than 29 hours (1.19 days) from first symptoms.
  • Treatment slows progression by a maximum of -0.53 per day (less with poor treatment).
    • Good treatment[What defines "good"?] means that the disease will progress by 0.31 per (.84 -.53) day at this rate, slowing the infection to require 3.22 days to reach 100%. This works out to slowing the infection to a minimum of just under +.013 per hour.
  • For a healthy* patient, immunity increases by 0.6441 per day (~.0268 per hour) when sick, taking 1.55* days to reach 100% immunity.
  • When 100% immunity is reached, the patient is immune and safe, and severity of the infection immediately begins to decrease by 0.7 per day (or ~.03/hour), so it takes less than a day and a half before the worst infection is fully cured.
    • When immunity is achieved, in the Health tab, the white "circle" next to the infection will change to a gold shield. The current progress of the (now healing) infection can still be seen by mouse-hovering over the entry.
(* A patient gains immunity more slowly with poor blood filtration (e.g. from a missing/damaged kidney), malnutrition (i.e. long-term hunger), or over the age of 50, so their time to reach immunity will be greater. Extremely vulnerable patients have only extreme options.)
Case studies
  • It has been observed in patients with normal beds, a room with "slightly dirty" to "dirty" cleanliness, well nourished, Medical care with skill ~6-10 and only herbal medicine (Tend quality ~40-50), will recover from their infections, even despite some few hours delay in starting treatment. It sometimes is a near thing, and may result in a longer recovery time from an end infection near/over 90% when they reach immunity, depending on the delay, their feeding schedule and the "luck" of the attending doctor. Malnutrition (from hunger) definitely slows the immunity process, as listed under Immunity Gain Speed.
  • It has also been observed that a prisoner in good health (age < 50, no health issues), well fed, in an excellent-quality hospital bed with a vitals monitor, and a Tend quality of 99% (high Medical skill using glitterworld medicine), gained Immunity more than 2:1 over Infection gain (from a 68 Immunity and 83 Infection, +32 v. +15). That's not a "maximum", but it may be close to a reasonably practical one, just as a benchmark.

All this math also means that it will take a patient almost 3 days, or more, to go through the process of first fighting and then recovering from an infection, besides recovering from whatever wound or ailment caused the infection in the first place. Yet another reason to provide prompt, sterile treatment for all colonists' wounds to avoid this in the first place.

Once an infection is gone from the system, so is any immunity to future infections, and a new infection will cause the process to begin again from scratch.

Default warning

Toward the end of a bad infection, once the infection becomes "extreme" (80% or more), you will get a bright red warning among the other notices on the right side of the screen saying:

"Medical emergency People are at risk for death because of severe illness..."

This alert appears regardless of whether that colonist is currently beating the infection or not, or will do so - the game doesn't do the math to predict whether the infection or the immunity will reach 100% first, but you should be able to. The warning is simply there to remind you that now may be the time to take drastic action, just in case you are losing the race. The notice will disappear when immunity reaches 100% (regardless of the current level of infection), or when the victim dies.

Prevention

In order to prevent infections, make sure that people and animals that have open wounds are in a clean/sterile environment for the initial treatment of any infection-prone wound (e.g. no natural flooring apart from rock, no dirt or blood on the floor, etc.). Clean any room before treating wounds.

Although a clean (or even sterile) room won't guarantee that a wound will not get infected, it will reduce the chance of an infection occurring, and is a worthy precaution to take. Any clean(!) constructed floor is better than dirt (some are better than others), and sterile tiles are better than generic floors. (See cleanliness for more details).

A triage area can be established near a killbox to tend to pawns quickly without having to trudge halfway across the map carrying the pawn to tend - the utility of this depends on the distance to a hospital and the number of pawns needing treatment. More pawns and larger distance make it more relevant, while a single pawn getting downed in the room next to the hospital would be better off taken to the clean room.

Treatment

As with any other disease: Make sure that the patient is rested, well-fed*, and treated whenever possible. Treatment is administered once every 12 hours, per infection. Infections progress very quickly, and missing a treatment can be a very costly mistake. Due to the rate at which they progress, you'll need at least a competent doctor and medicine in order to ensure that the affected person survives their infections.

(* Don't underestimate this one; anything more than "trivial" malnutrition will both allow the infection to progress more quickly and slow the immunity gain!)

As a last resort, if a colonist is about to die, don't hesitate to amputate* the affected part. It's better to have a colonist missing a part or two than a dead one, and they won't mind if you remove their infected parts, either.

* To amputate: Under the patient's Health tab is the Operations tab; "add a bill" to amputate the infected body part. You may have to/want to upgrade the patient's default "medicine" used for procedures - that's under Health/Overview. If an arm/leg is the target, sure to amputate the correct (left/right) limb - surgeons just do what they're told.)

Normal people

For colonists with 100% immunity gain speed, you will need at least 15% average treatment quality to ensure that one doesn't succumb to their infected wound(s).

Extremely vulnerable

For those with a base immunity gain rate of 39% or less, there is no chance that they will be able to survive a wound infection normally, even with 100% treatment quality for all treatments and rest in a hospital bed with vitals monitor connected. This includes some people with kidney and liver damage (physical or chemical).

To save the colonist you can do the following:

  • Administer healer mech serum- instantly treats the infection
  • Administer luciferium- if pawn has 23% or more immunity gain speed remaining initially, this gives pawn a chance to survive
  • Amputation
  • Part replacement

Amputation

If you know that a colonist might not make it, it's best that you amputate the part. Colonists that reach 80-90% disease progression with their immune systems unable to catch up should have their infected part amputated immediately if possible.

There is a chance that an amputation will fail, however, if not amputating will result in certain death it is best to take the risk. Besides, if you are amputating a hand, what does it matter if the surgeon manages to tear off the rest of the amputee's arm?

If the infection has progressed to over 97%, there is little to no chance your surgeons can successfully pull off an amputation in time. It's better to strip the sick colonist of their clothes and leave them to die or euthanize them to extract some Medical experience.

Part replacement

Besides amputation, you can also swap out the diseased part with a healthy one. If the surgery fails, however, you will risk another infection from the surgical cuts and stabs.

Version history

At around Beta 18 infections caused a reduction in part efficiency, allowing them to kill much earlier than usual if a critically injured vital body part is infected and the infection causes the efficiency of that body part to drop below zero.