- Random infection by a bacteria containing one antigen
- Eating weeds, especially the Laburnum and Deathcap
- Cave Flies
- Random infection by an evolved bacteria containing an unknown toxin - these often contain multiple antigens and histamines or toxins. To prevent unknown toxins from evolving in the game, periodically reset it using the Emergency Kit.
In normal creatures, when infected by a bacteria, antibodies rise to a high level, and then the bacteria will stop reinfecting the creature. In a normal creature, high levels of antibodies give an immunity to antigens, but they do not fight or cure infections. Therefore, creatures can be innoculated against antigen-caused disease. LummoxJR has developed Active Antibody Genes that will enable antibodies to react with antigens and reduce antigens.
Disease can be detected using the Observation Kit, but not all of the time - glycotoxin, for instance, is undetected. (See Observation Kit for more information.) The Science Kit may also be helpful - but Ageing is a good 'toxin'!
Curing Disease In Creatures 1
To cure a Creatures 1 creature of almost any disease, isolate it to prevent distraction, make it eat something (preferably not honey), and give it something that will reduce its hotness not increase its coldness (Gentian is excellent), because all antigens use up glucose and cause high temperatures. Other herbs can also be beneficial. Bedrest is also important, but not as vital as eating and reducing hotness.
Please note that the "IV Cough Medicine" will only affect sneezing (not coughing) in Norns (and not Grendels). IV Energy from the Health Kit can also be helpful in dire cases, although it causes some pain when used.
There is also an affliction in Creatures 2 known as "Star Disease" or Fibrillation. It is caused by low ATP, which can itself be caused either by starvation, drowning or genetic disorders.
If caused by drowning, 100% Defibrillant from the Science Kit and removal from water solves the problem. If caused by starvation, then inject the creature with 100% Metabolism Transplant from the Science Kit, and then 100% Defibrillant. Keep on alternating these injections until the afflicted creature can survive on its own. If caused by a genetic disorder, the cure depends on the specific genes involved, or there may be no cure at all.
While a norn is fibrillating, all organs take damage, and if the Brain organ dies, the norn dies. Therefore if untreated this condition is universally fatal.
Creatures 3/Docking Station
Histamines are one of the most common diseases in the game. These come in two forms, Histamine A and Histamine B. In Docking Station a good cure is lemon, which the hoverdoc will recommend. In Creatures 3 however the most effective cure is 2x100% anti-histamine and a stay in a warm, disease-free place.
In all games, diseases can be fatal. Norns from Creatures 1 and Creatures 2 tend to be more susceptible to disease than in later games -- excessive breeding over the Warp in Docking Station has produced norns that are almost (if not completely) invincible! This is not necessarily a good thing, as without drives such as illness, norns have no need for intelligence; a norn which was never hungry, tired, bored or ill would be very boring to watch, as the best course of action would be for it to do nothing!