History Main / BeneficialDisease

* In ''Animation/KikoRiki'', the episode "How to Catch a Cold" subverts this. Eldaph catches a cold and Fluff thinks it would be cool to catch one too because that way, he'd get treats. However, when he sees Joshie and Jumpy sick but feeling bad, he decides he doesn't want to get sick.

** Related, though not precisely this trope (since they aren't exactly diseases per se): Pokémon can only have one of six [[StandardStatusEffects non-volatile status ailments]]: Burn, Freeze, Paralysis, Poison, bad Poison (most prominently from the move Toxic), and Sleep; with the exception of a Poisoned Pokémon becoming badly Poisoned, or using Rest to replace one of the other ailments with Sleep, it's impossible for an enemy Pokémon to inflict a different one of the six on a target. Thus there are strategies like having a Pokémon hold a Flame Orb (which gives it the Burn status at the start of battle) to prevent other, more limiting status ailments from being applied. Some effects, such as Poison Heal also make these status beneficial on top of granting immunities to the others.

*** [[http://scienceblog.cancerresearchuk.org/2013/06/25/no-doctors-did-not-inject-hiv-into-a-dying-girl-to-treat-her-cancer/ Actually]], they used HIV as a vector for gene therapy, the genetic material that makes HIV deadly was replaced with genes that modified a few T-cells, that were removed from the patient and infected in a petri dish before putting them back back, attack cancer cells.

** Several "evil" diseases provide growing bonuses at the cost of penalties in other areas, in effect becoming a DeadlyUpgrade. The fans were quick to notice that the PrestigeClass Cancer Mage from ''Book of Vile Darkness'' can adapt to diseases, hoarding bonuses while ignoring the penalties.
** The same book include some evil spells with a disease component. That means the caster must be infected with the appropriate disease to cast them. Such spellcasters often use another spell called ''suspend disease'' to keep the infection from having any debilitating effect.

* Technically it's poison, not a disease, in ''VideoGame/UltimaIV'', but being poisoned does have the side effect of making anyone who has it immune to sleeping spells - which is immensely useful in a part of the Great Stygian Abyss, where the party is confronted by multiple Balrons chain-casting sleep spells.

* The Vinn Parasite in ''Webcomic/DriveDaveKellet'' re-jiggers its hosts DNA through a comorbid retrovirus. This results in [[MakeThemRot cytotoxic venom]], [[ShockAndAwe Bio-electrogenisis]], electropreception, and [[InvisibilityCloak chromatophores in the skin]]. The downside is that the parasite rejiggers the brain too, resulting in personality death.

* In ''Animation/{{Smeshariki}}'', the episode "How to Catch a Cold" subverts this. Eldaph catches a cold and Fluff thinks it would be cool to catch one too because that way, he'd get treats. However, when he sees Joshie and Jumpy sick but feeling bad, he decides he doesn't want to get sick.

* The Vinn Parasite in ''Webcomic/{{Drive}}'' re-jiggers its hosts DNA through a comorbid retrovirus. This results in [[MakeThemRot cytotoxic venom]], [[ShockAndAwe Bio-electrogenisis]], electropreception, and [[InvisibilityCloak chromatophores in the skin]]. The downside is that the parasite rejiggers the brain too, resulting in personality death.

* Creator/NealAsher's ''[[Literature/ThePolity The Skinner]]'': Set on a DeathWorld that has this gigantic leech whose bite carries a virus with interesting properties, "victims" become super-strong and nearly immortal and indestructible. Almost all animals on-planet are infected by it, as are most humans who live there. The real downside is that the evolutionary "purpose" is so predators can have permanent prey, and even if you can't die, it doesn't mean you can't feel pain/suffer a FateWorseThanDeath.

* ''Literature/FoundationSeries'''s ''Literature/FoundationsFear'': The childhood illness of BrainFever is an [[InvertedTrope inversion]] because catching "brain fever" makes one susceptible to R. Daneel's PsychicPowers. Hari Seldon had been lucky enough not to get sick at a young age, which means Danell could not read his mind.

* The protagonist of ''VideoGame/DeepFear'' is immune to TheVirus because he's got [[spoiler a cold]].

** The series has Vampirism, which comes in [[VampireVarietyPack many regional variations]] (which also explains the differences in the disease's characteristics between different games). One universal characteristic is that it renders the sufferer [[IdealIllnessImmunity immune to all other diseases]]. In addition, the ''VideoGame/{{Skyrim}}'' variation of the disease, Sanguinare Vampiris, bestows the [[LifeDrain Vampiric Drain]] spell.

*** The Corprus Disease, a "divine" disease created by [[BigBad Dagoth Ur]] using the [[CosmicKeystone Heart of Lorkhan]], makes the sufferer TheAgeless and immune to all other disease. It also unfortunately comes with a nasty case of BodyHorror and severe mental degradation. [[PlayerCharacter The Nerevarine]] has the negative effects cured as part of the main quest, leaving only the positive ones.

** In ''Skyrim'' The Afflicted are infected with a disease that that gives victims the ability to spray acid out of their mouths. [[GameplayAndstorySegregation Even though it is supposed to be an infectious disease it can't be spread to the player.]]

* In ''VideoGame/MegaManX'', the Maverick Virus is this to Zero. The virus is supposed to according to WordOfGod, the virus had ironically fixed a programming bug in his "cognitive" system that made him very violent and disobedient, to the point where he performed a HeelFaceTurn soon after and joined the Maverick Hunters to face down other Mavericks. (The virus is supposed to make other robots violent by removing their inhibitions and their empathy).

* Vampirism in ''VideoGame/{{Castlevania 64}}'' might take away your primary weapon and ability to recover health by eating food, but it also ''makes you unable to die''. You still take damage, but you keep going even when your health reaches zero. As long as you keep in mind that you'll get a NonStandardGameOver if you remain in vamp status until next midnight it can be situationally useful if you keep an eye on the clock and keep a Purifying Crystal on hand. It best comes into use when forced to navigate the [[ThatOneLevel odious Garden Maze]] and its invincible DemonicSpiders, since you handily fight a vampire ''immediately'' before entering the maze...

* ''VideoGame/Griftlands'': The Bog Parasites[[note]]acquired on Day 2 of Rook's campaign or brawl[[/note]] are generally a harmful nuisance, as they take up a card in your decks and usually deal 1 damage when they're drawn. However, draw and/or use them enough times and they 'Hatch' into special-effect cards.

* In ''Webcomic/Sorcery101'', lycantropy is considered an infectious disease, usually spread through biting. There's even a (fairly simple) cure. In a classic case of CursedWithAwesome, however, it comes with a laundry-list of advantages -- most notably rapid regeneration. Brad, who's a werewolf, was once offered a cushy job in return for biting his new boss's daughter... because she was currently dying from inoperable cancer, and he'd rather see her alive, if occasionally furry, than dead.

* One episode of ''WesternAnimation/BenTen'' has Ben get sick with a cold, which causes problems when he transforms into aliens because he still has the cold when transformed and it has weird effects on his alien forms (Wildmutt becomes blind due to it clogging up his sensory organs and Fourarms is weakened and smells really bad), but when he transforms into Heatblast, it causes his fire powers to be replaced with ice powers, which prove useful.
* In the ''WesternAnimation/BettyBoop'' episode "Betty Boop's Kerchoo", Betty Boop has "a cold in [her] nose", which seems to make her win because when she sneezes, it pushes her car along (although having a car with the ability to go over other cars when a lever is pushed helps too).

* Played with in the ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' episode "The Cutie Pox". The titular illness makes Apple Bloom able to do amazing things like [[FluffyTamer tame lions]] and [[GoodWithNumbers do complex equations]], and it seemingly prevents her from getting tired as she tap-dances all night without seeming tired even afterwards, however, it also forces her to do those things, making day-to-day life difficult.

* ''WesternAnimation/TheSimpsons'': Mister Burns is apparently alive only because he's got so ''many'' diseases that they're all blocking each other out from outright killing him.

* Malaria helped you cope with syphilis in later stages (by causing such dangerously hot fevers that the syphilis bacteria can't survive) -- Dr. Julius Wagner-Jauregg even got a Nobel Prize for finding out during UsefulNotes/WorldWarI. Of course nobody cares now because of the discovery of penicillin.

* In the ''{{Literature/Newsflesh}}'' world, both Marburg Amberlee (a cure for cancer) and "Kellis flu" (a cure for the common cold) were ''meant'' to be this trope. Unfortunately for that world, no-one knew that when those two engineered viruses met, the result would be a ZombieApocalypse. A cancer- and cold-free ZombieApocalypse, granted.

* ''Series/SesameStreet'': In one episode, Telly gets something called "triangle-sneeze-[[SomethingItis itis]]", which makes him sneeze whenever a triangle is near. However, this is the only symptom so it's not like he has to rest or anything, and the sneezing comes in useful when they use it to find some valuable triangular objects.

* The Wiki/SCPFoundation notes that people with diabetes are somehow immune to the SpontaneousHumanCombustion [[http://www.scp-wiki.net/scp-081 Virus]].

* The Rot in ''VideoGame/{{Armello}}'', the King loses health each round from it, but any Hero infected with Rot doesn't really suffer any ill effects unless they fight someone else with Rot, in which case the one with a higher Rot score gains a bonus dice.
* In ''VideoGame/DarkestDungeon'', most diseases are crippling stat reductions that last until cured between quests. However, rabies actually gives a sizable damage bonus, while only reducing accuracy somewhat. It usually helps to leave rabies uncured on characters who are main damage dealers and already have dependable accuracy.
* In ''VideoGame/DarkSoulsI'', the handful of Blighttown's original residents who are not infected by the disease are instead infested with Quelaag's spider eggs. Grotesque as this infestation is, it seems to have at least prevented the blight infection.

* The protagonist of ''VideoGame/DeepFear'' is immune to TheVirus because he's got [[spoiler: a cold]].

** There's also an interesting interaction with the Toxic effect and Dung Pies. In Blighttown, certain enemies shoot toxic darts at you. This inflicts a devastating damage over time effect that is usually a death sentence unless you have the curative item. There's an item called Dung Pies, however, which inflict a much less harmful "strain" of the same effect. If you're on the verge of being infected by Toxic, quickly using a Dung Pie will infect you with the less harmful strain, which is much easier to survive.

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* Doctors are experimenting with using viruses to treat antibiotic resistant bacteria. These viruses are specialized for infecting specific bacteria and are not capable of infecting human cells (so it's really a [[SubvertedTrope subversion]]; these viruses are making the ''bacteria'' sick, not you, and it is very much a detrimental disease for the bacteria). Bacteria can develop resistances to the viruses, but by doing so lose their resistance to antibiotics.

* Doctors are experimenting with using viruses to treat antibiotic resistant bacteria. These viruses are specialized for infecting specific bacteria and are not capable of infecting human cells. Bacteria can develop resistances to the viruses, but by doing so lose their resistance to antibiotics.

* The Vinn Parasite in ''Webcomic/{{Drive}}'' re-jiggers it's hosts DNA through a comorbid retrovirus. This results in [[MakeThemRot cytotoxic venom]], [[ShockAndAwe Bio-electrogenisis]], electropreception, and [[InvisibilityCloak chromatophores in the skin]]. The downside is that the parasite rejiggers the brain too, resulting in personality death.

This trope is related to diseases that can be cured by either a medical treatment or the body's self-defense mechanism. The characters may elect to not cure or prolong the infection to gain the maximum benefit from the disease. For immunity/superpowers arising from disabilities of a more permanent nature, (disabilities caused by genetic mutations, accidents or general inborn traits), see DisabilityImmunity. For example, sickle-cell anemia that arises because of a genetic mutation resulting in lowered life expectancy, but also provides a degree of immunity against malaria, is Administrivia/NotAnExample of this trope. It is an example of Disability Immunity, since sickle cell anemia is permanent. On the other hand, cowpox, which is a disease that provides immunity to a much deadlier disease called smallpox, is a good example of this trope.

* One of the best examples of this trope in real life is [[https://en.wikipedia.org/wiki/Sickle_cell_disease Sickle cell disease.]] It's a genetic disorder that causes the victim's blood cells to become brittle and sickle-shaped, leading to decreased oxygen levels in the body. This condition is caused a hemoglobin gene inherited from the parents, and its severity depends on whether the person in question has one copy of the defective gene or two. If the person has two, then they develop the disease, but if the person only has one, then only some of their blood cells become sickle shaped and they become a carrier. [[https://www.newscientist.com/article/dn20450-how-sickle-cell-carriers-fend-off-malaria/ Studies have shown that carriers for the gene are at lower risk of Malaria,]] since the parasite that causes the disease is unable to reproduce in red blood cells with defective hemoglobin. As a result, areas where the sickle cell trait is commonly found are also areas where Malaria outbreaks have often occurred.

* One of the best examples of this trope in real life is [https://en.wikipedia.org/wiki/Sickle_cell_disease Sickle cell disease.] It's a genetic disorder that causes the victim's blood cells to become brittle and sickle-shaped, leading to decreased oxygen levels in the body. This condition is caused a hemoglobin gene inherited from the parents, and its severity depends on whether the person in question has one copy of the defective gene or two. If the person has two, then they develop the disease, but if the person only has one, then only some of their blood cells become sickle shaped and they become a carrier. [[https://www.newscientist.com/article/dn20450-how-sickle-cell-carriers-fend-off-malaria/ Studies have shown that carriers for the gene are at lower risk of Malaria,]] since the parasite that causes the disease is unable to reproduce in red blood cells with defective hemoglobin. As a result, areas where the sickle cell trait is commonly found are also areas where Malaria outbreaks have often occurred.

* ''FAPP'' ({{NSFW}}): Every living thing in the world of Jizzral, or those that enter it, are infected by a phenomenon called "the Fappening"; it causes those affected by the infestation to quickly recover from any injury to point of being practically immortal, receive abnormally increased sexual urges, and undergo random and strange physical mutations that often fall into the lewd area. There is no cure (at least, not any known ones), and the effect is spreading to many other worlds, and yet it does not seem malicious since the inhabitants of Jizzral consider it natural.