Illness

With the infamous guinea pig disease now a thing of The Sims past, Sims can now catch a few different diseases, each with their own symptoms and method of catching - they're contagious, too.

Guinea Pig Disease
This disease was introduced in Livin' Large. Sims can catch it if they are bitten by a guinea pig that has a dirty cage, or from other Sims who have been infected with it. Objects cloned from the guinea pig can also cause this disease. Sims infected with it will sneeze and cough frequently, and their Comfort and Energy motives will decline. Infected Sims will die if not treated.

The action of a given instance of Guinea Pig Disease is restricted to a single lot, so a Sim who gets infected will not display symptoms, be infectious, or die outside of the lot he got infected. A Sim with GPD can safely go to a community lot or be invited to another Sim's house as a visitor. It is possible for a Sim to be infected on multiple lots, however.

Treatment

 * 1) Keep the sick Sim(s) home from work or school, and try to keep their Comfort and Energy motives up.
 * 2) Buy the Forgotten Guinea Pig painting. It will clear the disease from the household after 16 Sim hours.
 * 3) If the Sim is an adult, have them use The "Concoctanation Station" chemistry set. If a Sim uses it when the disease is present on the lot, there is a chance that he or she will make a white potion, which will cure the disease. Additionally, there is a good chance that the Sim will make a blue potion which will restore three random motives. While this will not directly cure the disease, anything that keeps a sick Sim's motives up will help them recover from it.

Montezuma's Revenge
Also known as "Poopy Pants" (the name used by Maxis in the code), this disease was introduced in Vacation. It's a form of food poisoning, and Sims can get it from eating at buffet tables when their Hygiene is low. It will not kill a Sim, but is uncomfortable. Sims with this illness will have trouble keeping their Bladder meter full, and will spend plenty of time in the bathroom.

Treatment
The disease is not deadly, and will go away on its own. Try to keep the affected Sim's motives up.

Nervous Breakdown
Introduced in Superstar, this is not a disease per se. It will occur if a famous Sim has repeated failures in Studio Town. The Sim will enter a catatonic state and lose Comfort, Fun, Bladder and Fame points. A mention of it will appear in the tabloid.

Unleashed Mystery Illness
This was reportedly introduced in Unleashed. It was dubbed the "Mystery Illness" because its exact nature and origin was unknown. Its existence was inferred, but never officially acknowledged or confirmed, and reports of it spread around the Sims community. Reported symptoms are those of the Guinea Pig Disease, but it does not require the presence of a guinea pig. It could reportedly affect both humans and pets, and reported symptoms in pets include listlessness and an inability to maintain the Hunger motive.

It does not appear to exist as a separate entity, but may have been the result of a bug involving existing illnesses. What it is, and whether it exists at all, remains subject to dispute. Investigations by various hackers have discovered that there is no reference to disease in any of the files that come with Unleashed (see this thread at Simblesse Oblige), and that code which claims to cure the disease refers to a disease controller file which was included in Vacation, which actually contains code for Poopy Pants.

Woodworker's Disease
There have been rumors that a Sim who keeps operating the woodworking table in a room with no windows will get sick, or at least will develop a nasty cough; however, this has never been confirmed. An inspection of the crafting bench's file shows that there is no code for disease in it.

Symptoms

 * Coughing – Causes a drop in comfort.
 * Sneezing – Causes a drop in comfort.
 * Nausea – Causes a drop in comfort.
 * Vomiting – Causes a drop in comfort. Affected Sim will run to a toilet, or vomit on the floor if they can't find one.
 * Diarrhea – Causes a drop in bladder.
 * Fatigue – Causes a drop in energy.

Contagiousness
Food poisoning and morning sickness cannot be passed between Sims. All other diseases can, to varying degrees. Mysterious disease is more contagious than flu, which is more contagious than a cold, which is more contagious than pneumonia.

Fatality
If certain illnesses are not cured within ten days, the Sim will die from illness. Children are taken away by a Social Worker before they get a chance to die. Toddlers and babies cannot get ill. The mysterious disease can kill a Sim in under 24 Sim hours, so it's possible for a child to die of the mysterious disease.

Call in sick
This interaction is available by calling work on the phone, and allows a Sim to miss work without fear of being fired. It becomes available one hour before the carpool arrives, and remains available until the Sim is one hour late. If the Sim is not actually sick, its success depends on job performance. It will always succeed if the Sim is actually ill.

Morning Sickness
Morning sickness almost always happens when a Sim is pregnant and in the first trimester. It also has the same symptoms as food poisoning. If the Sim is a female and she didn't plan for a baby, or if it's a male Sim and he wasn't recently abducted, then it is most likely he/she just ate some spoiled food.
 * Symptoms – Vomiting, Nausea
 * Fatal? – No
 * Contagious – No

The only way guaranteed to prevent a Sim from getting morning sickness is to download a mod that will stop it from happening. Otherwise its intensity varies from Sim to Sim.

Food Poisoning
There is a 5% chance any time a Sim eats spoiled or burned food that the Sim will get food poisoning. This can occur if food spoils while a Sim is eating it.
 * Symptoms – Vomiting, Nausea
 * Fatal? – Yes
 * Contagious – No

Cold
There is a 1% chance any time a Sim goes to work or school that the Sim will catch a cold. Infected Sims will suffer from coughing and sneezing fits, causing drops in comfort.
 * Symptoms – Coughing, Sneezing
 * Fatal? – No, but will become pneumonia if not cured within ten days
 * Contagious – Highly

Pneumonia
If the cold is not cured within ten days it will turn into pneumonia. The pneumonia has all the symptoms of both the cold and the flu, as well as sharp and sudden drops in energy in which a Sim appears to nearly pass out. If energy drops low enough, the Sim will pass out. Sims with pneumonia may die if not treated.
 * Symptoms – Coughing, Fatigue
 * Fatal? – Yes
 * Contagious – Slightly

Flu
If a Sim goes near cockroaches, there is a 5% chance they will catch the flu. The flu has all the symptoms of a cold with sharp drops in fun and energy as well.
 * Symptoms – Coughing, Diarrhea
 * Fatal? – Yes
 * Contagious – Highly

When the Beaker household in Strangetown is first played, there will be cockroaches near the refrigerator. Both Loki and Nervous will go to stomp on them and are likely to catch the flu. It is best to cancel out this action before they get there, and call an exterminator.

Mysterious Disease
Also known as "Virus", Sims can be infected with this when using the biotech station with low logic skill. It should be noted that this disease is highly contagious and can easily spread through the entire neighborhood in a matter of days.
 * Symptoms – Two random symptoms.
 * Fatal? – Yes
 * Contagious – Extremely

Rest
The best cure for all illnesses is rest. Keep the sick Sim away from healthy Sims, and keep their comfort and energy up by making them sleep and relax on the bed, until a message appears saying they are cured. If the Sim is able to meditate, this will also help.

Medicine
The medicine made with the biotech station cuts down the resting time needed to be cured of a sickness. Players who do not have either FreeTime (with up-to-date patches) or Apartment Life will need to get a mod from More Awesome Than You! for the medicine to work properly.

Orange Juice
If The Sims 2: Seasons is installed, drinking orange juice made from Tasty or Mouthwatering fruit will cure colds, or at least reduce the amount of time a Sim will need to rest.

Grandma's Comfort Soup
With The Sims 2: FreeTime installed, Sims with Family as their primary or secondary aspiration can achieve the aspiration benefit "Grandma's Comfort Soup". When eaten, it will cure any disease a Sim has. It is recommended to have AT LEAST one Family Sim in the household, whether it be mom, dad, the butler (controllable), or Grandma, just in case one Sim has the "Unknown Virus" or any other small illness. It is the first benefit for the Family aspiration, so it should be quite easy to achieve.

The Sims 3

 * Unlike in The Sims 2, there has been no confirmation of death by sickness in the Sims 3, nor of any contagious diseases.

Morning Sickness
Morning sickness will always happen when a Sim is pregnant and in the first trimester. Sims will randomly get the Nauseous moodlet and eventually they will vomit.

Food Poisoning
If a Sim eats spoiled or burned food there is a slight chance he/she will receive the Nauseous moodlet, and will vomit after several hours. They will then need a lot of rest. If this happens to kids, let them skip school. It is best to have high cooking skill to prevent this.

Tiberium Poisoning
Keeping Tiberium, a radioactive rock, in a Sim's inventory for a while will give them Nauseous moodlet and cut their mood down.

Eating Meat
If a Vegetarian Sim eats meat, he/she will receive the Nauseous moodlet and will vomit after a while.

Plasma sickness
When a normal Sim drinks Plasma or eats any plasma-based products he/she will get the Nauseous moodlet and vomit after two hours. Also, having a vampire Sim with the vegetarian trait drink plasma from Sims will cause him/her to get the Nauseous moodlet and vomit after a while.

Floor Hygienator Temporary Malfunction

 * Main article : Floor Hygienator

When a floor hygienator isn't created by Sims that have completed the "Master Inventor" Skill Challenge, it will have a temporary malfunction that causes it to backfire to the Sims. Thus, it will give Nauseous moodlet for 2 hours and the Sims will continue to vomit.

Experimental Treatment
This is an option unlocked for Sims that join Medical career track. It's quite tricky that sometimes experimental treatment will cause the Sims to feel dizzy and continue to pass out for a while, or it will give Nauseous moodlet for 2 hours continues to vomit.

Mummy's Curse

 * Main article: Mummy

If a Sim loses a fight with a Mummy, they may become cursed. If the curse is not lifted after two weeks, the Sim will die.

The Sims Medieval
Unlike The Sims 3, The Sims Medieval offers both injury and disease. Death by plague is also present. Diseases will usually give Sims a bad moodlet and can be cured by visiting a Physician or by applying curative tonics and/or health salves. Every disease is contagious in this game.

Sickness
This is the first and the least serious form of a disease. It can easily be cured by applying Weak Curative Tonics, or by visiting a Physician. Gives a -10 moodlet.

Infection
If a sickness is not cured, then it will turn into an infection. Infections are usually cured by applying Moderate Curative Tonics (unlocked by Quest) or by visiting a Physician. Gives a -20 moodlet.

Disease
An infection will turn into a disease if cure is not met. This kind of disease is quite serious. It can easily be cured by applying Strong Curative Tonics or visiting a Physician. Gives a -30 moodlet.

Plague
In case a disease is not cured, it will turn into a plague. Plague can cause a Sim to die, so it has to be cured immediately. When a Sim has a plague, black smoke will appear above their head. A Plague can only be cured by visiting a Physician. Gives a -50 moodlet.

Minor Injury
This is the least serious form of injury. It can easily be healed either by applying Weak Health Salves or visiting a Physician. Gives a -10 moodlet.

Moderate Injury
When a minor injury is not healed, it will turn into a moderate injury. Moderate injuries can be healed by applying Moderate Health Salves (unlocked by Quest) or visiting a Physician. Gives a -20 moodlet.

Major Injury
The most serious form of injury. The Sim will be in bandages. It can be healed by applying Strong Health Salves or visiting a Physician. Gives a -30 moodlet.