List of diseases

The following is a list of all 17 Diseases and their categories in Plague Inc. and Plague Inc: Evolved.

Standard Plagues

The Standard Plagues are the first kind of plagues available to the player. Most of them are highly realistic, and represent real-life pathogens. The first playable Standard Plague is Bacteria. In order to unlock the next plague type, the player must beat the plague they've most recently unlocked on Normal or higher difficulty. Each plague comes with its own abilities, strengths, weaknesses, and playing styles.

• Bacteria - A resistant plague that has unlimited potential.
• Bio-Weapon - A disease engineered by man to be extremely deadly.
• Fungus - Spores that grow on or inside a body.
• Parasite - A microscopic animal that feeds off its host. 
• Prion - An extremely deadly protein, like Mad Cow Disease, that affects the brain.
• Nano-Virus - An incredibly small virus with a built-in kill switch, which was also engineered by man.
• Virus - An uncontrollable, incredibly small sickness that makes duplicates of itself in cells.

Trivia

Three of the Standard Plagues were all the plagues present in the game Pandemic 2, which served as inspiration for Plague Inc. They were the Virus, Bacteria, and Parasite.

Special Plagues

The Special Plagues are expansion packs of Plague Inc. and Plague Inc: Evolved. Unlike the Standard Plagues, their pathogens present little to no realistic threat in real life. They add new Soundtracks, mechanics, traits, and most of them add new Genetic Code categories.

• Necroa Virus - a plague that can turn people into zombies and control them.
• Neurax Worm - a parasitic alien worm that makes the victim do what it wishes inside the the victim's brain. 
• Shadow Plague - A plague that can turn people into vampires.
• Simian Flu - A plague that can infect both humans and apes. Makes apes intelligent.

Availability

Plague Inc. (Mobile Version)

No Special Plagues are unlocked from the beginning. The first Special Plague, the Neurax Worm, is unlocked after the Premium Version has been bought and the player has beaten all Standard Plagues in Brutal difficulty or higher. After beating the most recently unlocked Special Plague in Normal difficulty or higher, the next one will be unlocked.

The player can also buy each Special Plague individually for $1.99.

Plague Inc: Evolved (PC Version)

The Simian Flu and Shadow Plague are available since the start, while the other two are unlocked through normal gameplay. The Neurax Worm is unlocked after beating Fungus in Normal difficulty or higher. While the Necroa Virus is unlocked after beating Prion on the same circumstances.

Trivia

• Neurax Worm is the only Special Plague that doesn't have its own special genes nor an organization directly dedicated to combat it.
• Curiously, the order of Special Plagues (left-to-right in Plague Inc, and top-to-bottom in Plague Inc: Evolved), correlates with the increment of Gene Categories exclusive to it, as the Neurax Worm has none, the Necroa Virus has one, the Simian Flu has 2, and the Shadow Plague has 3.
  • Whether this is intended or not is unknown.

Scenarios

• Black Death - an incredibly deadly scenario, called Yersinia Pestis in-game, which is a recreation of the black death.
• Frozen Virus - A 30,000-year-old virus that was thawed recently.
• Mad Cow Disease - A dangerous prion that is spread through animal meat.
• Nipah Virus - An deadly virus from India.
• Smallpox - An extremely deadly, almost extinct virus.
• Swine Flu - H1N1 Virus, an influenza strain which started in Asian pigs.

Trivia

• An AIDS Scenario was planned, which would have involved the player using HIV/AIDS to wipe out humanity. The scenario was removed because the developers felt it was "too real", as HIV is a disease that still affects certain groups of people.