Prime universe
(Capcom's primary storyline)
See also: Plaga Type 2 and Plaga Type 3

Plagas (プラーガ purāga?) are arthropods of an unknown taxonomical order. Plagas are parasitic in nature, and can survive in a number of host organisms from humans to canines. How long Plagas have existed on the Earth is uncertain, but historical accounts indicate they are native to the Iberian Peninsula and were almost eradicated several centuries ago. In their native Spain they are known as Las Plagas, which translates as "the plagues".

Plagas naturally have at least four stages in their life cycle: egg, stage 'A', 'B' and 'C'. It takes within days for a hatchling to complete maturation into the 'A' stage, by which point they have taken control of the host's nervous system. A human victim of the so-called "Recessive Plagas" is dubbed a "Ganado", the Spanish word for a herd of animals, particularly livestock such as cattle.

Because of their ability to control human beings, new species of Plaga were genetically engineered by bio-weapons developers for use in terrorist attacks. For the purpose of clarity, this article will focus on the naturally-occurring species of Plagas as well as the species engineered by Los Iluminados.



The Plagas were the focus of worship in an isolated, mountainous region of Spain around the late 18th-early 19th century. Salazar, a nobleman of indeterminate rank, led a brutal crusade in the region against its followers. Surviving Plagas were sealed within caves beneath a mound, separated from the nearby village by a deep valley trench and a large body of water. A fortress was built above it, of which Salazar and his descendants took on the role of Castellan, intent on preventing the Plagas' escape.[1]

Resident Evil 4 Castle - Mine examine 1

Desiccated remains of Plaga.[note 1]

Around the Millennium, Osmund Saddler, a man with unspecified links to bio-weapons research, became aware of the organism and began plans to use the Plagas to gain money and influence on the international stage through the parasitization of others. Taking on the role of a Prophet, leading the cult "Los Iluminados" - Spanish for The Enlightened- Prophet Saddler gained the loyalty of Ramon Salazar, 8th Castellan, who agreed to release the Plagas to atone for his family's sins.[2] The two, and the village workers hired to conduct the excavation,[1] found the Plagas long since mummified in the low-oxygen environment.[3] Hope was restored several years later when the spread of a strange disease amongst the workers revealed the Plagas had survived in the form of spores and were in the process of growth within their new hosts.[3]

Having established a large research complex and military base around ancient ruins on a nearby island, Los Iluminados began work on studying the Plagas, and over time genetically-engineered as many as three new species, which were significantly more difficult to be removed from the host. These species were the Recessive Plagas, which took control of the host; the Dominant Plagas which left the host alone, allowed them to issue commands to the Ganados and imbued them with the ability to mutate at will; the third was the Queen Plaga, an organism living in the castle which asexually produced more eggs. As this offered great risk to Saddler's ability to control his growing organization, the Dominant hosts were limited to himself, Salazar, and Fr. Bitores Mendez, the village priest who helped him convert the local population, who would serve as an army to keep out spies.[1]

In continued human testing, Plaga research was found to mutate humans under certain circumstances, whether making them stronger, making them grow to giant proportions, or make them able to regrow entire bodyparts within seconds.[4] Human-animal hybrids were created with the Plagas as well, leading to the Novistador; the Verdugo and U-3.

First Daughter abduction plot

In 2004, Los Iluminados made their move for world influence in an ambitious plot. Due to a leak by Dr. Luis Sera, the Organisation became aware of the Plagas, and sent their agent, Jack Krauser, to obtain a Plaga sample on the group's behalf. Krauser was instrumental in the kidnapping of Ashley Graham, daughter of President Graham, on her way home from the University of Massachusetts; having previously served in an Army special operations force, his skills made it a success. Graham was taken to Spain and injected with a Plaga egg through a syringe. There, it was expected she would become a Ganado and be taken back to the United States and serve to conduct operations on Saddler's behalf. Though the US government kept the kidnapping a state secret, they received an anonymous tip linking Graham to the area. With many agents being investigated by the government,[5] only US-STRATCOM agent Leon S. Kennedy was forced to begin the investigation alone.

Meanwhile, Dr. Sera finally abandoned Los Iluminados and escaped the island base with a Dominant Plaga egg. Krauser, having become host of a Dominant Plaga himself, became a liability to both Saddler and the Organisation,[6] and was forced to call for agent Ada Wong to continue the investigation in his place, and take the sample from Dr. Sera in exchange for his protection.[7]

Over the course of the night, the different parties worked with and against one another. Kennedy was captured and implanted with an egg on the orders of Saddler,[8] who wanted him as an additional mole in the US. Dr. Sera shifted between whether to hand over the Dominant egg to Wong or Kennedy. Krauser and Wong turned on one another, while both claiming loyalty to Dr. Albert Wesker, their Organisation liaison. By sunrise, Fr. Mendez; Salazar; Krauser and Dr. Sera were dead, the Queen Plaga was destroyed, Leon Kennedy and Graham were free of the Plaga parasites, and the group's bioweapons research was in ruins along with their army of mind-controlled followers. With the death of Saddler, who stole the egg from Dr. Sera, Wong finally turned on Kennedy and took it on behalf of the Organisation, though helped Kennedy and Graham escape the island as explosives were set to cleanse the area.

In the aftermath of the incident, Wong followed orders from The Organisation to betray Dr. Wesker, and provided him with a Recessive Plaga, keeping the Dominant Plaga for her bosses.[9] Dr. Wesker was initially set-back by this double-cross, but was successful in obtaining the remains of a Dominant Plaga from the body of Krauser. Genetic modification of the two samples was conducted by Tricell on Dr. Wesker's behalf, resulting in the creation of the Type 2 and Type 3 species. The Spanish authorities made attempts to quarantine the mountains to prevent surviving Plagas from spreading, though refugees who fled from Los Iluminados were parasitised when they returned home. Los Iluminados itself survived in a reduced form, and many years later worked with Glenn Arias, who used genes from their Plagas to create the A-Virus.


Plagas are capable of altering their host's behaviour by attaching themselves to the central nervous system, in humans between the lungs and heart. The maturation and take-over of the human hosts can be very painful and cause internal haemorrhaging, coughing up of blood, swelling of blood vessels around the eyes, fainting, convulsions,[3] and hallucinations. For these reasons, child hosts of the parasites inevitably die soon after the eggs hatch.[1] The Plaga begins altering the host's biochemistry from birth, with the changing of the eyes to red being a common sign.[note 2] The Plagas also cause mutations in their hosts while increasing their physical strength and durability. For example, Ganados can remain standing after sustain several gunshot wounds, and some can wield heavy tools without difficulty. If the body is severely injured, adult Plagas may tear through the neck and use their own bodies in self-defence.

Plagas are a social creature, and hosts thereby also form a pack mentality.[10] Though hosts may communicate via speech, Dr. Sera's studies indicated that the Plagas themselves communicate via ultra-high frequency sound waves; a special organ exists to pick up these vibrations, which can be interpreted as commands.[11] This system allows for the Dominant Plaga hosts to issue commands to Ganados. It has been observed that not all Plagas will act well to each other. Even after gaining control of the mountains, Los Iluminados saw fit to execute locals, using an abattoir near the village and the castle dungeons for executions.[12] Ganado mutants such as the Gigantes also acted violently towards other hosts. Despite being host to a Plaga parasite, Kennedy was also attacked during his mission, and received a warning by Fr. Mendez of suffering consequences for going against them regardless of being a host.

Weaknesses and countermeasures

Los Iluminados recorded a number of manners in which the Plagas could be killed, including means which would not kill the host. Their research was for the ultimate goal of genetically-engineering a species which lacked these defects,[13] though their finalised Recessive Plagas still have a number of weaknesses.

Plagas are extremely sensitive to ultraviolet (UV) radiation, and thus avoid daylight. A radiation therapy procedure was developed by Dr. Sera's team, which would douse the patient in enough UV radiation to kill a Plaga without invasive surgery.[13][14] This procedure was used to treat Kennedy and Graham. In both cases, the Plaga killed was a hatchling, and it is believed the chances of survival are significantly lower for hosts of adult Plagas.[13][15] Relating to the UV treatment, Flashbangs were found to be effective as a means of killing Plagas that had emerged from their hosts at night.

The growth of hatchlings can be halted through certain forms of medication, as discovered by Dr. Sera's team, and this medicine can also kill unhatched Plagas.[15] Dr. Sera handed this medicine to Kennedy and Graham when they were too far away from the island laboratory to receive UV treatment.

It is possible that Recessive Plagas can be killed through the destruction of the host's nervous system in a way that will keep the host alive but in a paraplegic state. This was performed on Alexander Kozachenko to prevent a Plaga taking over his body. However, this was a Dominant Plaga genetically-engineered years later by another group.

Recessive Plaga life cycle

Resident Evil 4 - Las Plagas 1

Plaga A parasite replacing the head of its host

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

  • "Plaga A",[16] which are identified by their pulsating masses of flesh and waving tentacles, with the longest tentacle having a scythe-like blade. This blade can be used as a weapon to slash enemies if threatened. Plaga As have also been seen within the bodies of dogs, known as Colmillos.

Plaga B

  • "Plaga B",[16] which appear more hand-like in appearance. The tentacles of the "A" have become stronger and can serve to grab hold of nearby enemies. Midway down the body is a large mouth, which can bite into prey the size of a human head.
Plaga Infection

Plaga C

  • "Plaga C",[16] which appear more spider-like in appearance, the arms having thinned out and become long legs. C Plagas can, if needed, force themselves entirely out of a host's body to escape.


Further notes

  • 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 Plaga B 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, having the same "head eating" animation, but would just hit her, making her fall lifeless in the floor.
  • The English localisation of Resident Evil: Umbrella Corps inaccurately refers to the ordinary Plagas of Spain as "Dummy Plagas." They are referred to instead as "recessive" in the Japanese game.



  1. Due to a translation error, the English version inaccurately suggests these animals had fossilised, when they had in fact been desiccated, a different process.
  2. When Mendez ambushes Leon in the hallway of his house, Leon's irises when struggling against Mendez's strangulation of him briefly turned red, which led to Mendez deducing that Leon "carried the same blood" as the Los Illumnados. This occurred before the eggs hatched.
  1. 1.0 1.1 1.2 1.3 biohazard 4 Incubate.
  2. Resident Evil 4 (2005), file: "Castellan Memo".
  3. 3.0 3.1 3.2 Resident Evil 4 (2005), file: "Luis' Memo 2".
  4. Resident Evil 4 (2005), file: "Luis' Memo 3".
  5. Resident Evil 4 (2005), file: "Info on Ashley".
  6. Resident Evil 4 (2005), file: "Krauser's Note".
  7. Resident Evil 4 (2005), file: "Ada's Report 2".
  8. Resident Evil 4 (2005), file: "Chief's Note".
  9. Resident Evil 4 (2005), file: "Ada's Report 5".
  10. Resident Evil 4 (2005), file: "Luis' Memo 4".
  11. Resident Evil 4 (2005), file: "Ada's Report 1".
  12. Resident Evil 4 (2005), file: "Village's Last Defense".
  13. 13.0 13.1 13.2 Resident Evil 4 (2005), file: "Luis' Memo 5".
  14. Resident Evil 4 (2005), file: "Luis' Memo 5"
  15. 15.0 15.1 Resident Evil 4 (2005), file: "Letter From Ada".
  16. 16.0 16.1 16.2 Hamamura, Kaitaishinsho, p.92.
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