Plague Inc. Wiki
General Information Strategy Guides
Main Game | Cure Mode

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« Bio-Weapons are organisms or entities that replicate inside their target host and can be used to kill or incapacite. They are prohibited under international humanitarian law and deploying them is a war crime. »
— Description of Bio-Weapon in Plague Inc.: The Board Game

The Bio-Weapon is a genetically and biologically engineered and modified virus that was accidentally released from a laboratory. It is the final Standard Plague available in the game. It is quite similar to other diseases, primarily the virus standard plague type in physical appearance and in shape and size. However, unlike the previous plague types, the Bio-Weapon will grow progressively more lethal over the course of the game, making it more likely to kill off one's hosts before they are able to infect more people and causing quick detection. To win, the player must use the disease's special abilities to lower the lethality in order to avoid killing too many hosts too early. This quirk makes the Bio-Weapon ideal for speed run strategies, similar to Nano-Virus (cure starts at the beginning of the game). The interface of the Bio-Weapon also very strongly resembles an RNA Retrovirus.

General Information

Similar to Nano-Virus, the Bio-Weapon is a powerful yet artificial engineered entity. Seemingly behaving like a Virus, Bio-Weapon does not feature escalating devolution costs nor excessive mutations from DNA fragmentation. A key feature of the Bio-Weapon is that its lethality will increase passively throughout the game. By default, the Bio-Weapon has slightly higher infectivity than usual, and is better suited to rich countries than average.

Bio-Weapon's innate lethality increment occurs randomly on a daily basis, eventually going exponential if left unchecked.

Gradual Lethality

Every in game day, the game will roll a random chance for the Bio-Weapon to increase lethality naturally. As the game progresses, the chance of lethality will increase exponentially. Nucleic Acid Neutralization will reset the exponential growth rate to zero, Gene Compression reduces lethality growth, Deactivate Modified Genes removes set amounts of lethality.

Special Abilities


  • The Bio-Weapon has an advantage of +0.4 adaption/effectiveness by default in rich countries.
  • In early versions of the game, a biohazard icon was used to represent this type of disease.[1]
  • In December 2015, Ndemic Creations announced the sale of plush toys inspired by the design of Bio-Weapon, Nano-Virus and Neurax Worm.[2]
  • In January 2016, Bio-Weapon was added to the Multiplayer Mode.[3]
    • In Evolution of 20 of Plague Inc.: Evolved released in July 2016, some disease-related aspects were balanced, including Bio-Weapon's resistance towards cure.[4]
  • In December 2019, the Armageddon expansion of Plague Inc.: The Board Game was released, in which two plagues were added, these were Bio-Weapon and Fungus.[5]
    • In the Board Game, the Bio-Weapon presents certain abilities, these include Festering Corpses, in which it collects DNA in countries where its population is completely dead in order to make the pathogen stronger. Although there is a possibility that it can eradicate itself since it has limited infectivity.[6]

Stages of Evolution

Stage 1
Stage 2
Stage 3
Stage 4



  1. Tamarit, Vicent (2012-10-06). "Plague Inc., estrategia desde un nuevo punto de vista". [Plague Inc., strategy from a new point of view] ABC (in Spanish) Archived from the original on April 23, 2022. Retrieved on April 22, 2022. (Screenshot of the game interface in one of the first versions of the game when it was released in 2012)
  2. "Plague Inc. T-shirts and Plush toys now available!" (2015-12-11). Ndemic Creations Official Website Retrieved on April 19, 2022.
  3. "Evolution 17 - New Bioweapon for Multiplayer and Tutorial added". Steam Retrieved on April 19, 2022.
  4. "Evolution 20 - Multiplayer balance update" (2016-07-21). Steam Retrieved on April 25, 2022.
  5. "Plague Inc: Armageddon out now!" (2019-12-04). Ndemic Creations Official Website Retrieved on April 19, 2022.
  6. Nieva, Jason (2019-04-19). "Plague Inc.: The Board Game's Armageddon Expansion Now On Kickstarter". Retrieved on April 25, 2022.
Standard Plague Types