Disease damage appears as a yellow rectangle
Old Splat
Disease is one of the few status effects in RuneScape. It is caused by being damaged by Zogres, Diseased Kebbits, Skogres and Fever Spiders, from the scarabs during Dealing with Scabaras, by failing to pick the lock on a zogre coffin, or failing to cut a scrapey tree in Trouble Brewing.
When a player has disease, shown by a yellow hitsplat (File:Diseasesplat.png), the player's skills are reduced by a random amount. Recovery takes one minute per level reduced, which can potentially be a long time.
The only skill that is not affected by disease is Constitution. All other skills may be reduced randomly by disease, taking away a number of skill points equal to the number on the disease splat. It only lowers one skill at a time and can lower the same skill multiple times in a row.
Wearing an inoculation brace provides protection against the effects of disease by preventing the reduction of skill levels, but it does not cure or immunise against disease. Alternatively, bathing in the thermal bath in Oo'glog does cure and briefly immunise players against disease.
Curing disease
Skills gradually recover on their own, but for an instantaneous recovery, potions from Herblore can be used. Restore potions recover Combat skills except Prayer and Summoning, while Super restore recovers all other skills and a limited amount of Prayer and Summoning.
The effects of disease can be countered with Relicym's balm. Drinking one or two doses reduces the effect, while three cures most disease altogether. Disease inflicted by scarab swarms and traps in the dungeon encountered in Dealing with Scabaras requires four doses to be cured immediately. Instead of clicking the potion, a player may click the now-yellow lifepoints indicator to automatically drink their balm.
Bathing in the thermal bath in Oo'glog cures disease and temporarily immunises players against being infected.
The unicorn stallion's (level 88 Summoning required) 'Cure' effect cures both disease and poison, but requires some Summoning points.
The Bloated leech's (level 49 Summoning required) Blood Drain scroll heals disease, including poison and stat damage, at the cost of some life points.
The Cure Other, Cure Me, and Cure Group spells in the Lunar spellbook will also cure disease.
Disease is cured upon death and respawn. It may be easier (and cheaper) to bank all items and get killed, or die in a safe activity such as the Duel Arena.