How to Use This Document #
Mechanical conditions (Blindness, Paralysis, Charmed, etc.) are listed first — these are effects with defined game mechanics that a character can be in at any time regardless of location.
Diseases follow in two sections:
- Universal diseases — can occur anywhere, spread by standard vectors
- Regional diseases — tied to specific Mystara locations, with exposure rates and recurrence patterns
Cure Disease (Cleric 3rd level) cures most standard diseases. Exceptions are noted. Some diseases require higher-level magic or specific treatment.
Stat losses: Unless noted as permanent, stat losses from disease restore fully on recovery. Permanent losses require Restoration (Cleric 7th, costs 1 CON from the Cleric permanently per casting) or Wish.
Part I — Mechanical Conditions #
These are not diseases. They are magical, physical, or mental states with defined mechanical effects. Most are temporary; some are permanent without magical intervention.
Blindness #
Source: RC Cause: Light or Continual Light spell cast directly at a target’s eyes; certain monsters (Medusa gaze partially); some traps and magical effects. Effect: Cannot see. –4 to all attack rolls. All opponents effectively have rear attack bonus (+2 HR, no shield bonus) against the blinded character. Movement at half speed; must move carefully or risk falling. Duration: Varies by cause. Spell-caused blindness: typically until Cure Blindness (Cleric 3rd) is cast, or DM-determined duration. Cure: Cure Blindness (Cleric 3rd). Note: Permanent blindness (from some monster abilities or failed saves) requires Restoration.
Charmed #
Source: RC Cause: Charm Person, Charm Monster, Charm Animal spells; monster abilities (vampire gaze, harpy song, nixie touch, dryad charm, etc.). Effect: The charmed character regards the charmer as a trusted friend and ally. They will not attack the charmer and will follow reasonable requests. They retain their own personality and will refuse requests that violate their alignment or endanger their life — but interpret the charmer’s intentions charitably. Intelligence is not impaired; the character can still think, just not about harming the charmer. Duration: Indefinite until Dispel Magic or the source’s condition is met (charmer dies, charmer releases, etc.). Characters may save again periodically (DM determination: typically monthly, or when the charmer acts obviously against their interests). Cure: Dispel Magic (MU 3rd); death of the charmer; Remove Curse for some monster-charm effects. Note: The charmed character does not know they are charmed. They believe their regard for the charmer is genuine. This is the most socially dangerous condition in the game.
Confusion #
Source: RC Cause: Confusion spell (MU 4th); some monster abilities. Effect: Each round, roll 2d6 for the confused character’s action:
- 2–5: Attack nearest creature (friend or foe)
- 6–8: Stand confused, doing nothing
- 9–12: Act normally Duration: Spell-caused: 2 rounds + 1 round per caster level. Cure: Dispel Magic; duration expiration.
Deafness #
Source: RC Cause: Horn of Blasting (save vs. Death Ray or deaf for 2d6 turns); Silence 15′ Radius (not true deafness — magical silence); some sonic attacks. Effect: Cannot hear. –1 to initiative. Cannot hear verbal communications, approaching enemies, or auditory warnings. Spellcasters who rely on verbal components: at DM’s discretion some spells may be impossible to cast while deaf (the character cannot gauge their own pronunciation). Duration: Horn of Blasting: 2d6 turns (temporary). Permanent deafness from some sources requires Restoration. Cure: Duration expiration for temporary cases; Cure Disease or Restoration for permanent cases.
Fear #
Source: RC p.35 Cause: Fear spell (MU 4th); monster abilities (dragon aura, Night Spider terror, wraith proximity, etc.); some magical items. Effect: The affected character flees at maximum speed away from the source of fear for the duration. They drop held items (DM determination). They cannot take offensive actions while fleeing. They do not stop to help allies. If cornered and cannot flee, they cower (–2 AC, no actions). Duration: Spell: 2 rounds per caster level. Monster ability: varies (typically 1d6 rounds; some are 1 turn). Cure: Remove Fear (Cleric 1st); duration expiration; Dispel Magic. Note: Characters immune to fear (certain high-level effects, magical items, class abilities) are entirely unaffected. Morale effects on monsters use the same mechanical category but are not curable by Remove Fear.
Insanity #
Source: RC Cause: Contact Outer Plane spell (failed save — each question beyond the safe limit risks insanity); some Immortal or extraplanar encounters; severe trauma at DM discretion. Effect: Varies by DM determination. Standard Contact Outer Plane insanity: character is incapacitated and must rest for a number of weeks equal to the number of questions that caused the insanity. During this time, the character is non-functional — they can be cared for but cannot adventure or perform complex tasks. Duration: Rest-dependent. The Contact Outer Plane table specifies weeks of rest required. Cure: Rest (mandatory — no magical shortcut for Contact Outer Plane insanity). Other insanity sources may be curable with Heal (Cleric 6th) at DM discretion. Note: Some insanity effects (from Outer Plane contact specifically) cannot be magically cured — only rest resolves them. This is intentional; it represents the genuine cognitive damage of contact with entities beyond mortal comprehension.
Paralysis #
Source: RC Cause: Magical sources only — ghoul touch, carrion crawler tentacles, hold spells, wyvern sting, some magical traps, certain monster abilities (manscorpion paralysis, various spider venoms). Effect: Complete immobility. The paralyzed character cannot move, speak, or take any action. They remain conscious and aware. All attacks against them gain +2 HR and ignore shield bonuses. Duration: Typically 2d4 turns (ghoul) or by spell duration. Some venoms specify hours. Cure: Cure Light Wounds releases ghoul paralysis (RC specific — physical manipulation of the paralyzed muscles); Dispel Magic for spell-based paralysis; duration expiration for most venom-based paralysis; Neutralize Poison for poison-paralysis. Note: Paralyzed characters in water drown. Paralyzed characters in combat are effectively helpless targets — they are not dead, but they are as vulnerable as if they were.
Petrification (Turned to Stone) #
Source: RC Cause: Flesh to Stone spell (MU 6th); Medusa gaze; Basilisk gaze; Gorgon breath; some other monster abilities. Effect: The character is transformed entirely into stone — their exact pose at the moment of petrification preserved. They are not dead, not alive in an active sense; they are suspended. The stone form is durable but can be physically damaged (a petrified character has no HP as stone — a sufficiently strong blow can shatter them permanently). Duration: Permanent until reversed. Cure: Stone to Flesh spell (MU 6th); some specific monster interactions (cockatrice touch in some editions — DM determination). The reversal must target the correct stone figure. Note: A petrified character who is shattered before being restored is dead — the destroyed stone cannot be restored to life even with Raise Dead. This makes transportation of petrified party members a real tactical concern. Stone to Flesh does not restore a character who was shattered while petrified.
Part II — Magical Afflictions #
These are supernatural conditions caused by specific monsters or magical sources, distinct from standard diseases.
Green Slime Affliction (Slimy Doom) #
Source: RC p.181 Cause: Contact with Green Slime (the RC monster). Green Slime dissolves organic material on contact. Effect: The afflicted area begins converting to Green Slime. Flesh dissolves at a rate of 1d6 HP per round from the contact point outward. If not treated immediately, the entire character converts to Green Slime within minutes. Treatment: Fire or cold applied immediately to the contact area destroys the slime before it spreads. Cure Disease (Cleric 3rd) stops the conversion if applied within the first round of contact. If more than one round has passed: only magical fire (Burning Hands, Fireball, etc.) applied to the entire affected area — including surrounding flesh — stops the spread. This causes additional damage to the character. Cure: Cure Disease (immediate, first round only); fire/cold at the contact point. Note: This is the game’s most immediately lethal affliction after save-or-die effects. Every round of delay reduces options and increases damage from treatment.
Hivebrood Parasitism #
Source: AC9 p.68 Cause: Broodling implanted on a paralyzed host by the Hivebrood Broodmother’s offspring. Effect (over 24 hours): Host develops chitinous outer skin layer. Eyes film over. Movements become stiff and insectoid. The broodling adapts to and modifies the host’s metabolism. The host and broodling become a single creature — the host is controlled by the broodling’s hive-directive. After full transformation: The host retains their physical form but is effectively a broodling — their personality is suppressed, they serve the hive, and they retain none of their previous class abilities or decision-making. Treatment: Cure Disease or Cure All kills the broodling. However: the host permanently loses 1d6 points from each of Intelligence, Wisdom, Dexterity, and Charisma from the broodling’s metabolic modifications. The host permanently gains +1 AC from the chitinous skin (which remains even after the broodling’s death). Note: The stat losses and AC gain are permanent — Restoration can address the stat losses (at cost), but the AC gain remains. A character who has survived broodling removal is physically changed.
Lycanthropy #
Source: RC p.191, TM1 Cause: Wound from a lycanthrope that reduces the victim to more than 50% HP loss in a single combat encounter.
Lycanthropy is a human disease. It evolved in human populations, spreads through human physiology, and its transformation mechanism is calibrated to human biology. The disease’s behavior in non-human hosts reflects this fundamental incompatibility.
Effect on humans: Standard transmission. The victim begins showing signs within half the 2d12 incubation period — behavioral changes, heightened animal senses, vivid dreams — and fully transforms at 2d12 days. At full transformation the character becomes an NPC lycanthrope permanently.
Effect on demi-humans (all strains except Werefox/Elves):
| Species | Effect | Timeline |
|---|---|---|
| Dwarf | Fatal — biology incompatible with transformation | 2d12 days |
| Halfling | Fatal — violent systemic rejection | 1d6 days (faster) |
| Gnome | Fatal — chaotic partial transformations tear the body apart | 2d12 days |
| Elf (standard strain) | Fatal — dreamlike decline, transformation stalls at final stage | 2d12 days |
The exception — Werefox strain and Elves: The Werefox strain carries a fey harmonic absent from all other lycanthrope strains. Elven biology — itself fey-adjacent — recognizes this harmonic as compatible rather than foreign. An elf bitten by a Werefox and meeting the transmission threshold undergoes complete, stable transformation into an Elven Werefox. They do not die. The transformation is permanent and the character becomes an NPC unless a Cleric of 11th level intervenes within the 2d12 window.
Cure: Only a Cleric of 11th level or higher can cure lycanthropy — for all species, including demi-humans who are dying rather than transforming. The cure removes the infection; for demi-humans it prevents death. It must be applied before the transformation/death completes.
After full transformation or death: For humans, the character is permanently lost as a PC. For demi-humans, the character is dead. For elven werefoxes, the character is permanently changed — as with human lycanthropes, they become an NPC under DM control.
Lycanthropy in Glantri: See Regional Diseases — Glantri (Full Moons) for the Known World’s most notable lycanthropy concentration.
Lycanthropy, Bhut Variant #
Source: AC9 p.33 Cause: Contact with Bhut (AC9 monster). Effect: Similar to standard lycanthropy but transforms victims into Bhut — an undead-adjacent creature type. Does not carry the werefox’s fey harmonic. Kills elves on the standard 2d12 timeline. Kills all other demi-humans as per standard lycanthropy. Cure: Cleric of 11th level or higher within 2d12 days.
Mummy Rot / Advanced Leprosy #
Source: RC p.195, D&D Supplement 2, TM1 Cause: Mummy touch attack. Also: contact with infected relics from Surra-Men-Raa graves (see Regional section). Effect: Rotting disease. The afflicted character’s flesh begins to decay while they remain alive. Physical deterioration is rapid — death occurs within days without treatment. In the advanced leprosy form (slower progression): progressive loss of sensation, digits, and eventually vital function. Mummy Rot timeline: Death in 1d6 days without cure. Advanced Leprosy timeline: Slower (weeks to months), but equally fatal untreated. Cure: Cure Disease (Cleric 3rd) cures both forms if applied before death. After cure, healing magic (Cure Serious Wounds minimum) is required to restore the physical damage already done — Cure Disease stops the rot but does not reverse it. Note: A character cured of Mummy Rot at very low HP may survive the disease but still die from the accumulated damage. Cure the disease first, then heal immediately.
Dusanu Rot #
Source: AC9 p.65–66 Cause: Contact with the Dusanu (specific AC9 monster). Effect: Rotting disease similar in category to Mummy Rot but spread by a different vector. Causes progressive tissue decay. Cure: Cure Disease (Cleric 3rd).
Radiance Disease #
Source: Gaz3, Gaz13 (Glantri, Rockhome) Cause: Exposure to the Radiance (the magical energy source beneath Glantri) or contact with Blackmoor devices that draw on similar energy. Effect: Progressive rotting disease from magical radiation exposure. Unlike standard diseases, Radiance Disease is caused by accumulated magical energy rather than biological infection — it does not spread person-to-person. Progression: Stat losses accumulate over time proportional to exposure level. Extended proximity to Radiance sources can be fatal. Cure: Cure Disease treats symptoms temporarily. Full cure requires removal from exposure and extended rest. Some sources suggest this disease is incurable by standard magic at advanced stages — DM determination. Note: The Radiance Disease is relevant to Glantri campaigns specifically. Wizards who draw on the Radiance directly face accelerated exposure.
Red Curse Affliction #
Source: Red Steel Cause: Withdrawal from Cinnabryl (the metallic substance that suppresses the Red Curse on the Savage Coast). Effect: Supernatural affliction specific to the Savage Coast region. Characters without Cinnabryl protection develop the Red Curse — stat enhancements accompanied by progressive physical transformation and eventual loss of normal humanity. Cure: Regular Cinnabryl application prevents the Curse. Removing the Curse once contracted requires specific Savage Coast magical treatment. Note: This is a campaign-specific affliction. Outside the Savage Coast setting, this disease is not applicable.
Demonic Pestilence #
Source: IM2 Cause: Spread by Demons (Immortal-tier encounter). Effect: Supernatural plague spread by demonic entities. Effects vary by demon source but are uniformly severe — stat losses, rapid progression, and high lethality. Cure: Cure Disease (Cleric 3rd minimum) for mild cases. Severe demonic pestilence may require Heal (Cleric 6th) or Immortal-tier magical intervention. Note: This disease appears in Immortal-tier adventure contexts. Standard parties are unlikely to encounter it.
Part III — Universal Diseases #
These diseases can occur anywhere in the Known World given the appropriate vector. They are not region-specific.
Rat’s Disease #
Source: RC p.201 Cause: Giant rat bite (RC — giant rats specifically carry disease). Effect: Fever, weakness. Stat penalties at DM determination. Duration: 1 month recovery without magical treatment. Cure: Cure Disease (Cleric 3rd). Transmission: Giant rat bites only (standard rats do not transmit this version).
Wasting Disease #
Source: RC p.36 (reversed Cure Disease spell) Cause: Cause Disease (reversed Cure Disease, Cleric 3rd); some monster abilities. Effect: Progressive weakness and deterioration. Character loses 1 HP per day (temporary HP — restored on cure). At 0 HP from wasting: comatose. Movement and combat ability progressively reduced as HP declines. Duration: Indefinite until cured. Does not resolve naturally. Cure: Cure Disease (Cleric 3rd).
Scurvy #
Source: Gaz9 Cause: Extended lack of vitamin C (fresh fruit and vegetables). Common among sailors on long voyages, siege survivors, and anyone on iron rations for extended periods (typically 2+ months). Effect: Strength –1d4, Constitution –1d4. Joint pain, lethargy, bleeding from mucous membranes. Severe cases: death. Duration: Progressive — worsens the longer the dietary deficiency continues. Cure: Fresh fruit or vegetables (1 week of proper diet begins recovery). Cure Disease accelerates recovery. Stat losses restore fully on recovery. Prevention: Ensure ship manifests include citrus or equivalent. The Aqrab caravans always carry this — it is basic logistics.
Crud #
Source: D&D Supplement 2 Cause: Filth and dirty conditions. Cumulative exposure to unsanitary environments. Effect: General illness — fever, weakness, nausea. –1 to all actions while symptomatic. Duration: 1d6 days without treatment. Cure: Rest and cleanliness. Cure Disease accelerates recovery. Transmission: Exposure to filthy conditions (sewers, overcrowded dungeons, unburied dead). 5% chance per week of exposure in unsanitary conditions.
Dysentery #
Source: D&D Supplement 2 Cause: Contaminated food or water. Common at sea (stored water going bad), in cities during overcrowding, and in military camps. Effect: Dehydration, weakness. Constitution –1d4 while active. Character must be near water/latrine facilities at all times — movement is severely restricted during active episodes. Duration: 1d6 weeks without treatment. Cure: Cure Disease; clean water and rest. Transmission: Contaminated water or food. 10% chance when consuming questionable water sources without purification.
Spotted Fever #
Source: D&D Supplement 2 Cause: Giant tick bite. Transmitted through the bite. Effect: High fever, skin rash with distinctive spots. Constitution –1d4. Delirium during peak fever. Duration: 2 weeks without treatment; fatal in severe cases if untreated past 1 week. Cure: Cure Disease. Transmission: Giant tick encounter — any character bitten by a giant tick has 25% chance of contracting Spotted Fever.
Grippe (Flu, Belly Ache) #
Source: D&D Supplement 2 Cause: Common airborne transmission. The catch-all term for influenza-type illness, stomach flu, etc. Effect: Fever, muscle aches, nausea. All stats –1 while symptomatic. Cannot undertake strenuous activity. Duration: 1d6 days. Self-limiting. Cure: Rest. Cure Disease is effective but considered excessive for this condition. Transmission: 10% per week in populated areas during Grippe season (typically autumn/winter).
Bubonic Plague #
Source: D&D Supplement 2 Cause: Flea bites (specifically fleas from infected rats). The presence of dead rats in an area precedes epidemic. Effect: Massive swollen lymph nodes (buboes), extreme fever, blackened extremities. All stats –1d6. Death within 1d6 days without cure. Duration: Fatal within 1d6 days untreated. Cure: Cure Disease (Cleric 3rd). Very high-level Clerics may be able to mass-cure during epidemics. Transmission: 10% per day of exposure to infected fleas. 1% per week in a city with active plague rats but no direct flea contact. Note: The Black Plague of the Heldann Freeholds (see Regional section) is a variant of Bubonic Plague with specific regional characteristics.
Cholera #
Source: D&D Supplement 2 Cause: Contaminated water, food contact, flies, or hogs. Rapid transmission in any condition with poor sanitation and water contamination. Effect: Rapid dehydration from severe diarrhea and vomiting. Constitution –1d6. Death within days without fluid replacement and treatment. Duration: Fatal in 2–4 days without treatment. Cure: Cure Disease; fluid replacement (magical Create Water is literally life-saving during cholera). Transmission: 15% per day of drinking contaminated water. 5% per day near infected individuals without sanitary precautions.
Malaria #
Source: D&D Supplement 2 Cause: Mosquito bites in tropical or subtropical swamp regions. Recurring infection — once contracted, can recur throughout life. Effect: Recurring fever and delirium. Strength –1d4, Constitution –1d4 during active episodes. Episodes recur every 1d4 weeks indefinitely without complete cure. Duration: Indefinite recurrence. Each episode lasts 1d6 days. Cure: Cure Disease cures the current episode but may not prevent recurrence (DM determination — Malaria is particularly persistent). Full cure may require multiple Cure Disease castings over consecutive recurrences. Transmission: 5% per day in tropical/subtropical swamp terrain. 1% per week in temperate swamp terrain.
Small Pox #
Source: D&D Supplement 2 Cause: Airborne transmission. Highly contagious. Effect: High fever, distinctive pustular skin eruption. Severe cases: Charisma –1d4 permanent (scarring) or death. Duration: 2 weeks. Fatal in ~30% of untreated cases. Cure: Cure Disease before pock formation prevents scarring. Cure Disease after pock formation cures the disease but does not prevent permanent CHA loss from scarring. Transmission: 25% per day of close contact with an infected individual.
Tuberculosis #
Source: D&D Supplement 2 Cause: Airborne transmission. Develops slowly from initial infection. Effect: Progressive lung disease. Constitution –1d4 (permanent if untreated beyond 3 months). Blood coughing. Reduced stamina — half normal daily travel distance. Duration: Months to years untreated. Fatal in severe cases. Cure: Cure Disease early (within 1 month of infection) achieves full recovery. Late-stage cure prevents death but may not reverse permanent CON loss. Transmission: 5% per week of close contact with infected individual. 1% per week in overcrowded, poorly-ventilated conditions.
Typhoid Fever #
Source: D&D Supplement 2 Cause: Contaminated food or water. Common in military camps, densely populated cities. Effect: Sustained high fever, intestinal damage, rose-colored rash. Constitution –1d4. Delirium during peak fever. Death in ~20% of untreated cases. Duration: 3–4 weeks untreated. Cure: Cure Disease. Transmission: 10% per week in areas with contaminated water. 25% among soldiers sharing field water sources.
Typhus #
Source: D&D Supplement 2 Cause: Parasites (lice, fleas, mites). Common during sieges when sanitation breaks down and crowding increases parasite transmission. Effect: High fever, severe headache, mental confusion. All stats –1d4. Death in ~20% of cases. Duration: 2 weeks untreated. Cure: Cure Disease. Transmission: 15% per week during active siege conditions. 5% per week in overcrowded barracks with poor hygiene.
Yellow Fever #
Source: D&D Supplement 2 Cause: Jungle or swamp mosquito bites. Limited to tropical and subtropical environments. Effect: Fever, jaundice (yellowing of skin), severe internal bleeding. Constitution –1d4. Death in ~50% of severe cases. Duration: 1–2 weeks. Survivors develop immunity. Cure: Cure Disease. Transmission: 10% per day in jungle or tropical swamp terrain during mosquito season.
Advanced Leprosy #
Source: D&D Supplement 2, TM1 Cause: Direct contact with infected individuals or materials. Slow transmission. See also Mummy Rot (same disease, different vector). Effect: Progressive nerve damage, loss of sensation, eventual loss of extremities. Charisma –1d4 (permanent from disfigurement). Strength –1d4 from limb loss in late stages. Death in late untreated stages. Duration: Months to years. Very slow progression compared to other diseases. Cure: Cure Disease at any stage stops progression. Restoration required to reverse permanent stat losses from late-stage leprosy. Transmission: 1% per week of direct contact with infected individual. Very low transmission rate — the disease’s danger is its slow progression and the difficulty of detection before significant damage has occurred.
Part IV — Regional Diseases (Known World) #
These diseases are tied to specific locations in the Known World. Exposure rates and recurrence follow the table from the source material.
Transmission rates:
- ★ = 1% per week of exposure. Epidemic lasts 1d6 weeks.
- ★★ = 10% per exposure check (once per epidemic). Epidemic lasts 1d4 months.
Mau-Mau Fever ★ #
Location: Aloysius (Ierendi Islands); also spread by Mau-Mau flies throughout the island chain Source: TM1, Gaz4 Recurrence: Permanent (endemic) Symptoms: Heavy sweating, pale skin, skin rashes Mechanical effects: Strength –3, Constitution –3 Progression: Death if not cured within one month Cure: Cure Disease (Cleric 3rd) Transmission: Mau-Mau fly bite. 1% per week of exposure on Aloysius; higher in areas with active fly swarms during the Mau-Mau mating season (early fall).
Bugbear Typhus ★★ #
Location: Altan Tepes Mountains Source: TM1 Recurrence: Winter months Symptoms: High fever, stupor alternating with delirium causing acute unpredictable berserk rages Mechanical effects: Constitution –3, Charisma –3, Strength +2 (the berserk rage is a genuine Strength increase — the character attacks uncontrollably) Progression: Death if not cured within one week. Highly infectious. Cure: Cure Disease (Cleric 3rd) Special: The berserk rage triggered by delirium means an infected character may attack party members without warning during fever episodes. Restraint may be necessary.
Griffin Pox ★ #
Location: Black Eagle Barony Source: TM1 Recurrence: Every 1d10 years (epidemic) Symptoms: Yellowish skin, red pimples, high fever Mechanical effects: Charisma –4 Progression: Highly contagious (25% chance of transmission on direct contact). Not typically fatal with treatment. Cure: Cure Disease (Cleric 3rd) Note: CHA loss is restored on cure.
Scum Variola ★ #
Location: Black Peaks Source: TM1 Recurrence: Spring Symptoms: Pale skin, pustular eruptions, nausea; affected individuals also develop a notably aggressive, scummy attitude (behavioral change during active illness) Mechanical effects: See Special below Progression: Death if not cured within one week Cure: Cure Disease (Cleric 3rd) Special: The “scummy attitude” is a genuine behavioral change — Chaotic alignment behaviors become more pronounced; social skills are effectively non-functional during active illness. An infected character may create political complications even after recovery if their behavior during illness was particularly problematic.
Yellow Orc Plague ★★ #
Location: Broken Lands Source: TM1 Recurrence: Famine years Symptoms: Yellowish skin, violent hiccup and coughing, brown buboes Mechanical effects: The buboes cause deadly choking — character must save vs. Death Ray daily or take 2d6 damage from the choking Progression: Death within one day without cure (the choking, not the fever, is the immediate kill mechanism) Cure: Cure Disease (Cleric 3rd)
Goblin Measles ★ #
Location: Cruth Mountains Source: TM1 Recurrence: Mid-winter Symptoms: Small red pustules all over body; larvae grow in the pus Mechanical effects: Progressive — each day without cure: Constitution –1 Progression: Death if not cured within one week (larvae reach vital organs) Cure: Cure Disease (Cleric 3rd) Special: The larvae are a biological component, not magical — Cure Disease eliminates them. A character cured of Goblin Measles may have minor scarring (DM determination on CHA impact).
Dumdum Fever ★ #
Location: Dwarfgate Mountains Source: TM1 Recurrence: Unpredictable Symptoms: Profuse drooling, runny nose, gaping mouth; progressive cognitive impairment Mechanical effects: Intelligence –2d6 (temporary, restored on cure) Progression: Can last a year without cure. Not typically fatal but the Intelligence loss can be severe enough to prevent the character from functioning or seeking help. Cure: Cure Disease (Cleric 3rd) Note: A character at INT 3 or below from Dumdum Fever may not understand what is happening to them or be able to communicate their need for a Cleric. Party members must recognize the symptoms and seek treatment on the infected character’s behalf.
Dwarven Bronchitis ★ #
Location: Dwarven underground settlements Source: TM1 Recurrence: Years of warfare (stress-triggered epidemic) Symptoms: High fever, coughing Mechanical effects: Constitution –1d4; berserk rage at sight of gold or gems (save vs. Spells to resist) Progression: Not typically fatal. Stress-related recurrence. Cure: Cure Disease (Cleric 3rd) Special: The gold/gem berserk rage is particularly problematic in dungeon contexts. An infected dwarf character who sees treasure must save vs. Spells or attack nearest creature while trying to reach the treasure. This can be… inconvenient.
Longship Pneumonia ★ #
Location: Farend, Landfall (Northern Known World) Source: TM1 Recurrence: Fall and Winter Symptoms: Coughing, loss of balance, memory, and direction; sea sickness Mechanical effects: See Special Progression: Cures itself after one month of mild fever (self-limiting). Not typically fatal. Cure: Rest. Cure Disease accelerates recovery. Special: The loss of direction and balance is significant for sailors — an infected navigator cannot reliably determine course. An infected ship’s crew makes all navigation checks at –4. The disease essentially removes the character’s sailing utility for the month of illness.
Hin Eczema & Acne ★ #
Location: Five Shires Source: TM1 Recurrence: Every 1d10 years Symptoms: Large pustules on face, skin rashes, dandruff Mechanical effects: Charisma –1d6 (temporary, restored on cure) Progression: Ugly but harmless. Not fatal. Cure: Cure Disease (Cleric 3rd); also resolves naturally over time (slower). Note: The most cosmetically disruptive of the Regional Diseases but the least dangerous mechanically. Social penalties may apply during active illness at DM discretion.
Kobold Flu ★★ #
Location: Hardanger Range (Soderfjord) Source: TM1 Recurrence: Unpredictable Symptoms: Coughing, loud sneezing, runny nose Mechanical effects: Strength –2, Constitution –2, Charisma –2, Dexterity –1d6 Progression: Can last a month. Not typically fatal. Cure: Cure Disease (Cleric 3rd) Note: The loud sneezing is a genuine stealth problem — any character with Kobold Flu automatically fails Move Silently checks and may reveal the party’s position at the worst possible moment. The DM should check for an involuntary sneeze at dramatically appropriate moments.
Black Plague ★★ #
Location: Heldann Freeholds Source: TM1 Recurrence: Every d% years (rare but catastrophic) Symptoms: Pale skin, heavy sweating, black swollen tongue, oozing buboes Mechanical effects: All stats –1d6 Progression: Death within 1d6 days without cure. The d% year recurrence means it may not appear in a campaign at all — but when it does, it is a civilizational event. Cure: Cure Disease (Cleric 3rd) Note: The “all stats –1d6” means a character with average stats (10s across the board) is at 4–10 in every stat by the time death approaches. This is the most mechanically devastating of the Regional Diseases. A Cleric NPC powerful enough to mass-cure during a Black Plague epidemic becomes immediately the most important person in the Heldann Freeholds.
Troll’s Cholera ★★ #
Location: Malpheggi Swamp Source: TM1 Recurrence: Permanent (endemic) Symptoms: Gray-greenish skin with warts, extreme pain, extreme weakness Mechanical effects: Strength –1d6, Constitution –1d6 Progression: Self-limiting — cures itself in 1d4 days after a violent fever. However: during the fever, roll 1d20 under Constitution or die in convulsions. This is the disease’s kill mechanism — the cure itself is the crisis point. Cure: Cure Disease before the violent fever phase prevents the save-or-die convulsion. After fever begins: must be cured before the convulsion check. Special: A character with low CON from the disease’s stat drain faces a convulsion check against a reduced CON. Early treatment is essential.
Glubfly Debility ★ #
Location: Sind Desert Source: TM1 Recurrence: Early Fall (Glubfly mating season) Symptoms: Caused by Glubfly sting during mating season Mechanical effects: Intelligence –1d4, Wisdom –1d4, Charisma –1d4; causes madness (save vs. Spells) Progression: Lasts one week. Not typically fatal. Cure: Cure Disease (Cleric 3rd); mental effects require Cure Insanity or equivalent. Special: The madness component (save vs. Spells) is separate from the stat loss — both must be treated. A character who fails the madness save is affected as per Insanity (see Part I) for the duration of the disease.
Gnoll’s Hepatitis ★ #
Location: Soderfjord Marsh (Summer) Source: TM1 Recurrence: Summer months Symptoms: Violent abdominal pains, nausea, convulsions Mechanical effects: Constitution –1 per day (not permanent — restored on cure) Progression: Potentially fatal as CON drains to zero. The progressive nature means a character who goes untreated long enough dies simply from the cumulative loss. Cure: Cure Disease (Cleric 3rd)
Brain Rot ★★ #
Location: Soderfjord City (also: a more severe strain spreads unpredictably through Soderfjord as a whole — see TM1) Source: Gaz10, TM1 Recurrence: Every 1d10 years (city epidemic) Symptoms: Sleeping disease — victim becomes progressively uncouth, careless, and cognitively impaired Mechanical effects: Intelligence –1 per day (permanent — each point lost requires Restoration to recover) Progression: Indefinite progression until cured. Not physically fatal, but permanent INT loss can reduce a character to animal-level intelligence. Cure: Cure Disease stops the progression. Restoration (Cleric 7th, costs 1 CON permanently from the caster per casting) is required to restore each lost INT point. Note: The most concerning long-term disease in the Known World from a PC perspective. A high-INT Magic-User who contracts Brain Rot and is not cured for a week has lost 7 permanent INT points. Restoration of 7 INT points costs the Cleric 7 CON — permanently. The economics of Brain Rot treatment are grim.
Purulent Cataract ★ #
Location: Southern Alphatia (drought years) Source: TM1 Recurrence: Drought years Symptoms: Searing eye pain; caused by rare Alphatian dust Mechanical effects: Blindness if not cured within one week (permanent blindness from untreated cataracts) Progression: Not typically fatal, but permanent blindness is severe. Cure: Cure Disease within one week prevents blindness. After blindness onset: Cure Blindness (Cleric 3rd) additionally required.
Bubonic Catarrh ★★ #
Location: Southern Ethengar (famine years) Source: TM1 Recurrence: Famine years Symptoms: Purulent (pus-producing) coughing; affects humans only Mechanical effects: Progressive — lung buboes form. Must be cured within a month or death from choking. Progression: Fatal within one month without cure. Cure: Cure Disease (Cleric 3rd)
Mummy Rot / Leprosy (Surra-Men-Raa variant) ★ #
Location: Surra-Men-Raa (religious site on the Thanegioth Isles) Source: TM1 Recurrence: Religious holidays (when relics are handled) Symptoms: Rotting skin caused by contact with old relics taken from infected graves Mechanical effects: As Mummy Rot — death in a few days if not cured Cure: Cure Disease (Cleric 3rd) Note: This is the same disease as Mummy Rot but spread through archaeological contact rather than mummy attack. Parties investigating Surra-Men-Raa ruins should handle all relics with cloth or metal tools — bare skin contact with grave goods carries the 1% weekly exposure risk.
Dysentery / Malaria (Thanegioth Isles) ★ #
Location: Thanegioth Archipelago Source: TM1 Recurrence: Permanent (endemic tropical diseases) Symptoms: Dysentery: fever, weakness, diarrhea. Malaria: nausea, delirium, recurring fever. Mechanical effects: Both fatal without cure within one week. Cure: Cure Disease (Cleric 3rd) Note: The Thanegioth Isles (where X1 Isle of Dread is set) have both diseases as permanent endemic threats. Parties operating in this region should have Cleric resources specifically allocated to disease management.
Sewers Typhoid ★★ #
Location: Thyatis City (overcrowding conditions) Source: TM1 Recurrence: Overcrowding-triggered Symptoms: Violent headaches and intestinal pains Mechanical effects: Madness occurs within one week (save vs. Spells); death occurs within two weeks without cure Progression: Two sequential crises — madness first, then death Cure: Cure Disease (Cleric 3rd) Special: The madness onset (week 1) means the infected character may actively resist treatment during week 2 when death approaches. Party members may need to physically restrain an infected character to get them to a Cleric.
Desert Meningitis ★ #
Location: Ylaruam Coast (drought years) Source: TM1 Recurrence: Drought years Symptoms: Loss of consciousness, severe headaches Mechanical effects: Intelligence –1 per day (not permanent — restored on cure) Progression: Death within one week without cure Cure: Cure Disease (Cleric 3rd)
Regional Diseases — Mechanical Summary Table #
| Disease | Location | Recurrence | Rate | Effects | Fatal? | Timeline |
|---|---|---|---|---|---|---|
| Mau-Mau Fever | Aloysius/Ierendi | Endemic | ★ | St –3, Co –3 | Yes | 1 month |
| Bugbear Typhus | Altan Tepes | Winter | ★★ | Co –3, Ch –3, St +2; berserk | Yes | 1 week |
| Griffin Pox | Black Eagle | 1d10 years | ★ | Ch –4; highly contagious | No | — |
| Scum Variola | Black Peaks | Spring | ★ | Behavioral + death | Yes | 1 week |
| Yellow Orc Plague | Broken Lands | Famine | ★★ | Choking 2d6/day | Yes | 1 day |
| Goblin Measles | Cruth Mtns | Mid-winter | ★ | Co –1/day | Yes | 1 week |
| Dumdum Fever | Dwarfgate | Unpredictable | ★ | Int –2d6 | No | 1 year |
| Dwarven Bronchitis | Dwarven caves | Warfare | ★ | Co –1d4; berserk vs. gold | No | — |
| Longship Pneumonia | Farend/Landfall | Fall/Winter | ★ | Disorientation; no navigation | No | 1 month |
| Hin Eczema/Acne | Five Shires | 1d10 years | ★ | Ch –1d6 | No | — |
| Kobold Flu | Hardanger | Unpredictable | ★★ | St/Co/Ch –2; Dx –1d6; sneezing | No | 1 month |
| Black Plague | Heldann | d% years | ★★ | All stats –1d6 | Yes | 1d6 days |
| Troll’s Cholera | Malpheggi | Endemic | ★★ | St/Co –1d6; convulsion death | Yes | 1d4 days |
| Glubfly Debility | Sind Desert | Early Fall | ★ | In/Wi/Ch –1d4; madness | No | 1 week |
| Gnoll’s Hepatitis | Soderfjord | Summer | ★ | Co –1/day | Yes | progressive |
| Brain Rot | Soderfjord City | 1d10 years | ★★ | Int –1/day (PERMANENT) | No | progressive |
| Purulent Cataract | S. Alphatia | Drought | ★ | Blindness | No | 1 week |
| Bubonic Catarrh | S. Ethengar | Famine | ★★ | Choking/lung buboes | Yes | 1 month |
| Mummy Rot/Leprosy | Surra-Men-Raa | Holidays | ★ | Rotting; death | Yes | few days |
| Dysentery/Malaria | Thanegioth | Endemic | ★ | Fever/delirium | Yes | 1 week |
| Sewers Typhoid | Thyatis | Overcrowding | ★★ | Madness (wk1); death (wk2) | Yes | 2 weeks |
| Desert Meningitis | Ylaruam | Drought | ★ | Int –1/day (not permanent) | Yes | 1 week |
Part V — Gaz10 Stat-Effect Diseases #
These six diseases from Gaz10 (The Orcs of Thar) are each defined by their primary stat effect. They can occur in any location where the associated monster populations live, not just the Broken Lands.
| Disease | Primary Effect | Notes |
|---|---|---|
| Orkinson’s Disease | Dexterity affected | —1d4 DEX until cured |
| Rheumatism | Strength affected | –1d4 STR; cold weather worsens it |
| Brain Rot | Intelligence affected | See Regional Diseases (Soderfjord) — same disease |
| Nervous Breakdown | Wisdom affected | –1d4 WIS; rest required |
| Head Cold | Constitution affected | –1d4 CON; self-limiting (1 week) |
| Stuttering | Charisma affected | –1d4 CHA; social penalties; spellcasters with verbal components check at –2 |
Appendix — Cure Disease Reference #
| Spell | Level | What It Cures |
|---|---|---|
| Cure Disease | Cleric 3rd | All standard diseases; most magical afflictions; stops Green Slime (round 1 only); stops Brain Rot/Desert Meningitis progression but does not restore permanent losses |
| Cure Blindness | Cleric 3rd | Blindness specifically |
| Neutralize Poison | Cleric 4th | Venom-based paralysis; cholera/dysentery dehydration effects |
| Remove Curse | Cleric 3rd | Some charm/fear effects; lycanthropy-adjacent curses |
| Restoration | Cleric 7th | Restores permanent stat losses (1 point per casting; costs caster 1 CON permanently) |
| Heal | Cleric 6th | Cures disease + restores HP simultaneously; preferred for late-stage disease |
| Remove Fear | Cleric 1st | Fear condition |
| Dispel Magic | MU 3rd / Cleric 4th | Charm, confusion, some paralysis; suppresses magical afflictions temporarily |
Sources: RC (Rules Cyclopedia) pp. 35, 36, 181, 191, 195, 201; AC9 (Creature Catalogue) pp. 33, 65–66, 68; Gaz3 (The Principalities of Glantri); Gaz4 (The Kingdom of Ierendi); Gaz9 (The Minrothad Guilds); Gaz10 (The Orcs of Thar); Gaz13 (The Shadow Elves); TM1 (Trail Map 1 / Mystara Almanac disease tables); D&D Supplement 2 (Blackmoor); Red Steel (Savage Coast); IM2 (Immortals module). All entries formatted for Skills-Based BECMI. American English throughout.
