As the name specifies, they are the most common type of disease to contract. They can also easily be cured however, either by potions or the Resist common disease effect.
Ataxia – Affects your Strength and Dexterity. It is contracted from the Slaughterfish, Diseases Alits or Plague Bears.
Brown Rot – Symptoms of this disease are most commonly insomnia and necrosis. It affects your Strength and Personality and is contracted from Bonewalker, Worm Lords or some Wraiths
Chills – Affects mind and general co-ordination. Drains Intelligence, Agility and Willpower attributes. Contracted from Bonewalkers or skeleton creatures.
Collywobbles – This disease affects your Strength, Endurance and Speed attributes. It may be contracted from a Shalk.
Crimson Plague – Drains Fatigue, Acrobatics and Athletics. May be contracted from Infected rats.
Dampworm – Drains your Speed, mainly. It may be contracted from the nix-hound creature, on repeated attacks and wounds.
Droops – Mainly a disease which makes you weak. It can be transmitted by all forms of kwama (from workers to warriors).
Greenspore – Affects the way you behave, including violent outbursts or mind effects. Attribute which suffers is Personality. Transmitted by the Slaughterfish.
Helljoint – Drains speed and Agility. Contracted from the Cliff racer.
Rattles – This affects your Willpower and Agility attributes. It is also contracted from some Nix-hounds
Rockjoint – Similar to Helljoint, drains your Agility attribute. It is contracted from the Guar or Alit.
Rotbone – Drains your fatigue, but is only a minor disease and quite rare.
Rust Chancre – Drains your Personality and Speed. It may be contracted from rats which reside in sewage wastes.
Serpiginous Dementia – Spreads erratic mind and behaviour effects. Attributes affected are Intelligence and Personality and it is contracted from the Bull or Betty Netch.
Swamp Fever – Drains Strength and Endurace. It is contracted from some diseased Mudcrabs.
Porphyric Haemophilia – An affect primarily associated with vampirism, and contracted as a result of vampire bites. Try not to get bitten, is my advice. Note that vampires don’t actually bite in game, it is contracted by just fighting one.
Sanies Lupus – Similarly to Porphyric Haemophilia, this is associated with Werewolves.
Witbane – Drains your Agility and can be contracted from Diseased rats, generally in the wild.
Witchwither – An effect which Paralyses you and is contracted by some of the NPC characters.
Wither – Drains your Strength and Endurance and is transferred by sea creatures such as Dreughs or some dreamers.
Yellow Tick – A mild common disease, it affects your Strength and Speed. It is contracted from the diseased Kagouti or some wolves.