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See also: Type-2 Plagas and Type-3 Plagas

Plaga (from Spanish, literally meaning "plague") are a species of parasitic organisms. Unlike the t-Virus, which turned its victims into mindless zombies, the victims of Plaga (such as the Ganado and Majini) become much stronger and highly resistant to pain, while working collectively to pursue their targets. Another side effect is the loss of higher reasoning, except in select subjects (who still are unable to shake off the need to obey higher orders) and the full compliance to the Dominant Species Plaga.

Resident Evil 4 - Las Plagas 1

Plaga parasite replacing the head of its host


Plaga were first discovered by a religious group in Europe known as "Los Iluminados" (The Enlightened Ones) in an unknown, rural region of Spain. The cult used the Plagas as a means of recruiting new members; however, the first castellan of the Salazar Family opposed the cult and sealed off access to the parasites in his castle.

Centuries later, Ramon Salazar, the eighth Salazar castellan, was convinced by Osmund Saddler, the new leader of Los Iluminados, to join Los Iluminados and break the seal that concealed the Plagas. The two hired the local villagers as miners to extract the parasites.

Fossilized Plagas

Fossilized plagas

Due to years of confinement, the Plagas parasites seemed dead. Some were later found fossilized (which at least takes millions of years) in the rocks below Salazar's castle. However, despite this, the Plagas were still alive at the microscopic level as spores within the fossils. The miners that were excavating the site inadvertently inhaled the spores, which after many years gave birth to the parasites within their bodies. Since then, Saddler was able to recreate the parasites wholly, injecting them in egg form into potential hosts.

Leon, Ashley, and the Third OrganizationEdit

The 3rd Organization learned of Plaga some time in 2004 when Ada Wong intercepted a desperate phone call from Saddler's chief researcher Luis Sera. Albert Wesker tasked the rogue former-US-SOCOM operative Jack Krauser to infiltrate Saddler's inner circle in the hopes of acquiring a Plaga specimen. Although not trusting Krauser, Saddler gave him a Dominant Species Plaga in exchange for Krauser's assistance. Saddler wanted to acquire Ashley Graham, daughter of the US President, in order to turn her into a host for the parasites and subsequently infect her father upon release. It was Saddler's ultimate goal for world control, with the president under his command. Krauser, as an American who had worked on Government missions before, was considered the perfect abductor for Ashley.

Saddler kills Sera and Leon fights Krauser, and is defeated, but later is revealed as alive and taken care of by Ada. Leon finds Ashley and proceeds to kill Saddler and recover the Dominant Species Plaga, but it is taken from him by Ada at gunpoint just after Leon defeats a transformed Saddler. Leon and Ashley then escape the self-destructing island via Jet-ski.

Ada betrayed Wesker and gave him a normal subordinate Plaga, delivering the dominant Plaga sample to a different organization she was actually loyal to. Wesker later retrieved a sample of the dominant Plaga from Krauser's corpse.

Uses in bioterrorismEdit

Five years later, within the African country of Kijuju, Chris Redfield and Sheva Alomar soon encountered Plaga-infected villagers. These plaga were modified through intensive research to enhance their performance and make them more effective B.O.W.s.

During the Eastern Slav civil war, Lickers were used as Plaga hosts, bringing them under the control of those carrying the Dominant Species Plaga. The secessionists required multiple Dominant Species Plagas, as their chosen council leaders eventually lost control to the parasites and had to be killed. During the same conflict, submissive-strain Plagas were somehow released and began infecting loyalist soldiers, secessionist rebels and civilians indiscriminately, creating infected humans that, while called Ganado by the locals, were more like the Majini of Africa. The loyalist government was also eventually revealed to be cultivating Dominant Species Plagas of their own.


Plaga are a type of parasite which alters its host's behavior by attaching itself internally to the nervous system. The undeveloped parasite is found between the lungs, beneath the heart, where it can tap into the host's spinal cord, as a link to the rest of the nervous system. Unlike other parasites, the Plagas are a social organism, meaning that they live together in social harmony. Luis Sera postulates that they have a collective intelligence akin to a hivemind, possibly communicating via ultra high frequency sound waves.

As a Plaga grows inside a host, the host can suffer from a number of symptoms (in addition to the influence of the parasite on the host's behavior). These include, but are likely not limited to: coughing up of blood, blood flowing from the eyes, convulsions, sudden unconsciousness, hallucinations, swelling and discoloration of blood vessels, and discoloration of the iris – usually to a reddish color. The eyes of an infected person can be seen to glow in dark conditions.

The parasites also have a high adaptability rate, as they can possess other kinds of organisms besides humans. (Ramon Salazar uses Plagas-infected wolves as guard dogs in his castle.) In addition to the Ganado, Saddler and his men also created several kinds of mutant creatures such as the El Gigante, the Regeneradores/Iron Maidens, Novistadors, the U-3, and Salazar's bodyguards, the Verdugos, as a result of genetic experimentation with the parasites and human specimens.

All of the members of Los Iluminados, including Saddler himself, have Plaga parasites implanted into their bodies. However, the ones used by him and his top underlings (Bitores Mendez,Jack Krauser, and Salazar) are superior to the regular Plagas, allowing their host a greater amount of independence.

Except for manifesting when sufficient trauma is induced on a host, Plagas have no true mutagenic effect on their hosts' body other than the distinctive red irises. While the Plaga infecting the Ganado and Colmillos can manifest and mutilate the body of their host, they do not actually induce any significant mutation or physiological change like Umbrella's myriad viruses do. However, certain feats by enemies in the game (such as lifting Leon into the air with one hand) suggest that the parasites can increase their hosts' strength. It is this attribute that hosts exhibit no outward sign of infestation besides discolored irises which make the Plagas such a dangerous threat, as they are much more subtle and invasive than Umbrella's viruses. The Plaga parasite does not stop their hosts from feeling pain however, unlike the t-Virus zombies, since the hosts have still retained their nervous system. Rather, they give their hosts better resilience against bullet wounds. Plagas are, however, weak towards UV light, although Dominant Strain hosts seem to be either immune or more resistant towards it, as evidenced by Saddler fighting Leon in the former's Plaga form during daybreak.

Also of note, according to a note written by Saddler, the subject's mindset does seem to be important when choosing a host ("the Plaga reflects the conscience of the hosts") suggesting that a Plaga's control over the host can be resisted, even overcome entirely. This seems to be a reference to Sera who was a host himself before managing to remove his Plaga. This might also explain the need to kill those who refused the Plaga, as they were obviously judged to be "incompatible". It also seems to be a literal description as well, at least in the case of the Dominant Species Plaga. As Krauser, who preferred close combat, developed a bladed arm to suit his needs.

Another side effect viewed in those infested with Plagas is an apparent biological instability. That is, they disintegrate into a black or yellow goo when killed. This is common with nearly all Plaga infested individuals, both Majini and Ganado. However, certain individuals, such as the first group of Ganado that Leon encounters in Resident Evil 4 and minibosses, do not disintegrate when killed. Plagas themselves also suffer the same fate upon death.

In the game, Plaga of the Ganado, Cultists, and Combatants only appear where the head is. Once a Plaga is exposed, the enemy will no longer sprint towards the victim.

The Majini located within Kijuju are infected with a different type of Plaga, created through extensive research. Majini have been shown to develop strange mutations, such as tentacles within their mouths, as well as the ability to fully open their mouth/jaw to expose tendrils to attack others. It has also been shown that the Plaga within Kijuju appear to already be fully awakened, and enter via the mouth or throat, already hatched, they seem to grown inside the host of another plaga which will later put it in another possible host, eliminating the need to inject the egg. These Plaga also do not appear to be harmed by sunlight, as they appear within brightly lit areas. Some strains have also been shown to fly after leaving the host body. Despite these new modifications, they are still vulnerable to bright flashes by flash grenades (i.e. UV light).

Plaga SpeciesEdit

Subordinate-strain Plagas - These are the normal Plaga species. They have no individual form by nature and it is not certain what dicates their manifestations.

Dominant Species Plaga - These are complex types of Plagas which were genetically modified in order for the host to retain control. They have three distinct abilities which separates them from Subordinate Plagas; they allow the host to retain their free will, control other Plagas and cause dramatic mutations in their host at will. They are opposite of the Subordinate Plaga, and allow the host to exert complete control over the parasite. The only known subjects to have ever been infected with this Plaga were Osmund Saddler, Bitores Mendez, Jack Krauser, Ramon Salazar, Ricardo Irving, and Alexander Kozachenko. Notably, this type of Plaga can create extremely powerful individuals, while having almost no detrimental effect on the host's mental capacity; something Umbrella's top virologists failed to do.

Plaga Life CycleEdit

Once it hatches inside a human host, the larval Plaga undergoes three primary stages of development.

  • Plaga A[1] - This is the first form of Plaga Leon will encounter. Their bodies are pulsating masses of flesh and waving tentacles, with the longest tentacle armed with a scythe-like blade that can slash at the player at a decent range. They are the weakest of the Plaga species and can be killed with minimal effort. Type A Plagas are commonly found in Villagers and Militia, and also control the weaker Armadura suits.
Resident Evil 4 - Las Plagas 1

Las Plagas parasite replacing the head of its host


Plaga B, erupting from a zealot's head.

Plaga Infection

Plaga C

  • Plaga B[1] - These Plagas are the second form of Plaga Leon will encounter infesting human hosts. They are often found inside the lower-ranking zealots, and are the second type which control Armaduras. This version of the Plaga can extend its entire body (being the Plaga itself) towards Leon and it will devour his head—being an instant kill. Other than this move, the B-parasite is capable of no other attacks. It is upon high risk that you should ever get close to this Plaga due to its one-hit kill effect; While not advisable, it can be killed with a knife. Interestingly, this type of plaga does not destroy the hosts head or body when revealing itself. As with the type A Plagas, it can be killed by using a flash grenade.
  • Plaga C - These Plagas (which somewhat resemble 'Facehuggers' from the Alien franchise) mostly inhabit the higher ranking zealots and militia. They are the most durable, can spit acid over some distance and detach themselves from their host following death. They are roughly equal to the A-parasites in terms of threat while attached, and are relatively weak when detached. While detached, they have a leaping grapple which lacks an animation for attacking from the side or rear, much like the Colmillos, meaning they can only use it when directly in front of Leon. Curiously, several are encountered in the game without hosts at all as in the case of the battle with Salazar. When without a host, a C-parasite will eventually die even if it has taken no damage from the player whatsoever. As they can't climb ladders, simply moving outside their immediate area is an effective way to kill them

Alternate Plaga ManifestationsEdit

  • Leech-like Plaga - When multiple Plagas are inserted into human hosts, they cause the host to undergo drastic physical mutations and become more leech-like in appearance. They are capable of regenerating the host's body(Regeneradores).


If a person has become the host of the parasite, the parasite's growth can be suppressed by taking medication. However, once the Plaga has hatched, then the only way to terminate the parasite without killing the host is for them to undergo a special kind of radiation treatment.[2] This extremely painful procedure has the possibility of impairing the host's consciousness, and may still kill the host if the Plaga has already matured into adulthood.

Luis Sera, a researcher who betrayed Saddler, helped design a machine which produced this kind of radiation after extensive research regarding how the Plagas might be removed. Ironically, he was tasked with finding a way to prevent any form of removal of the parasite by Saddler. Leon and Ashley, who had Plagas implanted into their bodies, used the machine to eliminate the Plagas, both managing to survive the operation as the Plagas had not reached their adult stage.

Plaga are also very vulnerable to bright light. They will only emerge from their hosts at night (except in The Mercenaries), and can be instantly killed by throwing a Flash Grenade at them (except for Spider Plagas that are attached to a host; with these, a flash grenade will dislodge them from their host, while it takes a second to kill them).

Also, a weapon called the Plaga Removal Laser 412 (P.R.L. 412), which is unlockable after completion of the Professional difficulty, can instantly kill any enemy infected with Plaga. It is presumably a weaponized version of Luis's machine.

The kind of radiation the Plagas are weak to seems to be UV light, since most lights used to destroy it are colored blue/purple, which means that it emits enough UV light. Another possible explanation for their photosensitivity is that they may react to a certain level of Candela (meaning that the brighter something is, the stronger it is against Plagas).

Although killing a Plaga once it has bonded with a human's central nervous system is likely to result in the death of the carrier, it is possible to kill the Plaga once it has bonded with a human's spine without killing the host. However, it will result in the individual being permanently paralyzed from the waist-down for the rest of their lives. This was especially notable with the Eastern Slav resistance member, Buddy.

Further NotesEdit

  • All lower level Ganado are shown to have lost their need for personal hygiene, due to the observations Leon makes in the first few chapters of the game and various water sources throughout the game.
  • The B-Plaga is the only of its kind (human host plaga) that can perform an instant death attack, by literally biting Leon's (or any other of the Mercenaries in the mini game) head off. This Plaga can also kill Ashley, but it will have the same "head eating" animation, but would just hit her, making her fall lifeless in the floor.
  • Plaga can be compared to crimson heads, because they appear after an organism's supposed death, and make the creature even more fierce.
  • In Resident Evil: Damnation the Licker becomes infected with a new parasite[citation needed], that allows it to be controlled by anyone who is infected with a Master plaga sample.


  1. 1.0 1.1 Biohazard 4 Kaitaishinsho Katei Ban, page 92
  2. Resident Evil 4, Luis' Memo 5


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