My post yesterday covered fantastical, magical diseases and how I think they ought to be implemented in Pathfinder. Today I want to continue along that same thread, but switch to real world diseases. The kind of stuff which killed our ancestors, and which adventurers in a medieval European themed fantasy setting are more likely to encounter.

To start, I want to make clear what I think diseases in a tabletop game should not be. They should not be a completely random affect. Players should not be constantly at risk to contract them, as they are in AD&D 1st ed. Diseases should never serve as a way for the GM to say “screw you!” to the players. Nor should players who contract a disease ever feel as though they could not have known what they were risking when they exposed themselves to it.

In my mind, diseases are traps. Traps which might be encountered in a dungeon, but can also be encountered during wilderness exploration. I don’t mean traps in a literal sense–obviously diseases aren’t triggered by pressure plates or trip wires. I view diseases as traps because they ought to be designed using the same methodology. When the players are in danger of contracting a disease, they must be able to recognize and avoid that disease through intelligent play, the same way they would avoid a trap. (Disable Device check not included).

For example, lets use the example of a fire trap. The players open the door, and the GM describes the room by saying that there’s an iron table and chairs in the center of the room, both of them slightly warped. The stone floor and parts of the wall are covered in dark smears.  Players now have enough information that they should know something is off about the room. They’re careful about entering, and in so doing, they discover that there are a few pressure plates within the room which activate a number of wall-mounted flame jets.

It’s the same when the players encounter the malaria trap. As they travel through the world, the GM tells them that shortly after noon, the forest they’ve been traveling through changes. Up ahead, it turns into a swamp filled with buzzing clouds of mosquitoes. Since the players know they’re playing in a game with disease, they have enough information to deduce that the swamp up ahead will be dangerous to travel through. They might choose to risk it, or go around it, or prepare some manner of mundane or magical protection for it. Regardless of what they choose to do, the world has become more dangerous, and more interesting, and requires them to make more informed decisions. And that’s good.

The question now becomes: Which diseases ought to show up in D&D? They need to be well known enough that players instantly know what kind of danger they’re facing when they contract it, and they should have methods of transmission which are distinct enough that they can be identified as dangerous situations by intelligent players. So I came up with a list of diseases which sprang to my mind, asked around for any I missed, then read the wiki entry for each of them, crossing off any which didn’t sufficiently meet my criteria listed above. I came up with a tentative list of 8 diseases which could be used in your game world.

I don’t imagine it’s necessary, but I would like to say before I begin: I don’t know what I’m talking about. I’m not a doctor, nor am I a biologist, nor even someone who got pretty good grades in a science class once. What I’ve written below is obviously simplified, and probably contains a factual error or two.

I’m not going to fully detail each of these with game rules, but I imagine all of them could be cured with Remove Disease if it is available. Any permanent effects from the disease would remain irreversible.

Malaria

How you get it: Being bitten by a disease-carrying mosquito.
What it does: Begins with flu like symptoms, followed by severe chills, fever, convulsions, and potentially a coma.

As mentioned above, swamps filled with mosquito are the perfect place for a malaria trap. I particularly like this one because it has an obvious sign of being present–clouds of insects–and there are a few interesting ways to avoid getting the disease yourself. Like a beekeeping suit, for example.

I’m not sure how the symptoms of malaria could be converted into game terms. Some penalties, with perhaps a permanent loss to constitution score? My understanding is that malaria is a disease which remains with you throughout your life, but aside from occasional flare-ups, a disease victim is able to have a relatively normal existence.

Rabies

How you get it: Being bitten by a disease-carrying animal. Most commonly a dog.
What it does: Hydrophobia, followed by mania, coma, and death.

This is one of the few examples where I think the idea of monsters carrying disease is a good one, since it’s actually how the disease is spread. In the real world, it seems as though dogs are by far the primary carriers of rabies, but in a fantasy world any number of creatures could be. A dire wold or giant rat with foam dribbling from their mouth is obviously something that players would want to be wary of.

Once a player has the disease, they can’t willingly enter water for any reason. After 1d6 days, the GM may randomly take control of them for a few moments as the mania begins to take hold. 2d6 days after that, the character dies if they have not had cure disease cast on them.

Leprosy

How you get it: Coming in contact with the breath of a diseased person.
What it does: Skin lesions, numbness, can lead to permanent skin, nerve, limb, and eye damage.

It’s worthy to note that, contrary to popular belief, Leprosy is neither highly contagious, nor does it make your limbs fall off. Since this is a fantasy world, you may wish to use a more fantastic version of the disease.

Since this disease is widely feared, but not actually very harmful or dangerous at all (compared to its hype), I think it makes the most sense for it to deal Charisma damage to the player. Since joints are affected, I think Dexterity damage is called for as well. A month after contracting the disease, the player permanently loses 1 charisma and 1 dexterity both, and the skin lesions begin to appear on their body. If the players allow either their Charisma or their Dexterity to drop as far as 3, then the disease will attack their eyes, making them blind.

Leprosy will never bring a player’s stats below 3.

The Black Plague

How you get it: Bitten by disease carrying fleas, which normally live on rats.
What it does: Large growths appear under the arms or near the groin, which ooze black puss. Within 2-7 days, the victim experiences a lot of blood vomiting, followed by death.

The best thing a player can do to avoid the black plague is avoid anyone infected with it like the plague. Because it’s the god damned plague.

If you’ve never made the time to read up on why exactly the black plague is still so present in human consciousness, here’s the cliffnotes. It killed between 75 million, and 100 million people in the 1400s. Considering that the total world population was estimated to be around 450 million, that means as much as 22% of the human race was killed by this disease. In Europe alone, between 30 and 60% of the population died. And they didn’t just die. They died in horrible pain, vomiting blood, and dying, all in a span of a week. And on top of all of that, the major outbreak during the 1400s wasn’t even the last one. There were further outbreaks of the disease for over 100 years afterword.

To put it another way, the Black Plague came close to wiping out humanity forever.

If your players hear about an area of plague, they damned well better stay clear of it.

Smallpox

How you get it: Smallpox is airborne if you are within 6ft of an infected person.
What it does: Distinctive full-body rash, weakness, nausea, vomiting, 30% fatality rate.

Smallpox is a lot like The Black Plague. It actually killed more people overall, but to my knowledge Smallpox did its killing over a larger period of time, and never took out such a sizable percentage of humanity all at once. In its own right, it is a horrifying and painful disease, and one which the players will want to avoid if they ever hear about an outbreak of it.

At least they’ve got a 70% survival rate if they do catch it, even if they’ll be laid up for a few weeks.

Syphilis

How you get it: Having the sex with an infected individual.
What it does: Painless lesions, rashes, a breakdown of mental abilities.

I’ve heard a lot of jokes about D&D players who engage in sex within the game, and I’ve even heard a lot of stories about it. I’ve never actually encountered a player or GM who was interested in exploring this aspect of the game. So for me, I doubt Siphilis would ever come up. Which is too bad, because it has some of the more interesting effects. I imagine there could be permanent wisdom loss, or perhaps loss of both wisdom and intelligence. Also, unlike most of the diseases on this list, a person with syphilis can continue to live a pretty normal life.

The existence of syphilis within a game world could serve as a useful tool for a GM who wants to reign in sex within their campaign.

Dysentery

How you get it: Consuming contaminated food or water.
What it does: Severe dehydration as a result of constant mucus/blood diarrhea. The dehydration can cause death.

Players should know not to eat stagnant water or spoiled food, and dysentery serves to give them an in-game reason to remember that. A player with Dysentery might need to consume a week’s worth of water rations in a day just to remain hydrated. And for the duration of the disease (which, to my understanding, seems to be about 1-2 weeks, depending on medication) the character would be almost completely incapacitated by abdominal pain and…well…pooping.

Tuberculosis, a.k.a. Consumption

How you get it: Contact with a coughing and sneezing person who has it.
What it does: Loss of appetite, fever, chills, fatigue, a bloody cough, death.

Like a number of the diseases above, T.B. is something the player contracts when they come in contact with a person who already has it. The bloody cough is the telltale sign of consumption. Players will want to distance themselves from anyone who has it. If they do contract it, they could probably continue adventuring for a short while, but with heavy penalties. Maybe just long enough to reach a cleric.

The section on diseases is one of the worst things I’ve encountered in the original Dungeon Master’s Guide so far. It has a page and a half worth of space in the book, but as best I can tell it’s nothing but a fun-leech. Something that Arneson came up with, and Gygax added complications to.* I’m honestly not sure why either of them thought rolling each month to determine if players caught a life-threatening disease would be fun. It strikes me as the kind of mechanic added because the designer places too high a value on creating ‘realistic’ games. Yet both Gygax and Arneson demonstrated elsewhere that they understood the dangers of excessive realism. Gygax even writes in the opening of the DMG:

“As a realistic simulation of things from the realm of make-believe, or even as a reflection of medieval or ancient warfare or culture or society, it [D&D] can be deemed only a dismal failure.”

So I’m really not sure why they chose to go this route. But suffice to say, I think it’s bad.

But the idea of diseases itself is not inherently flawed. Only AD&D’s application of it. And I don’t think I’m alone in that, as I’ve never seen anything even remotely resembling that disease rule in any other edition of D&D, or any retro-clone, that I’ve read. Diseases are still present somewhat, but they’re treated much more like poisons than anything else. The bite of a diseased animal or being cursed is the most common way to get a disease in Pathfinder. And while I don’t think that’s inherently bad, I think we could do better.

But before I move on to discussing my thoughts on how to fix the mechanics of how diseases are contracted, I’d like to bring up a second problem: how diseases are identified. The diseases in Pathfinder include such maladies as “Blinding Sickness,” “Cackle Fever,” “Devil Chills,” and Slimy Doom.” As fun and pulpy as these disease names are, I agree with Delta: diseases work better when they’re rooted in the real world. I get what they were going for (I’ve done it too), but goofy fantasy names like these never sound as good as they do in our heads. I do appreciate that Pathfinder includes more grounded diseases like Bubonic Plague and Leprosy, but I wish they’d stuck to Mummy Rot and Lycanthropy by way of fantasy diseases.

That doesn’t mean that I’m completely opposed to fantasy diseases. I just think they need to be integrated better. A fantastic disease should have a fantastic cause. It should also be more distinct and memorable than 1d4 strength damage once per day until 3 consecutive fortitude saves are made. The two I mentioned above are perfect examples of what I would deem to be good fantastical diseases. Mummy Rot is one of the most dreadful attacks possessed by a low level undead creature, with the potential to completely turn the target to dust. While Lycanthropy is so uniquely fantastical that I don’t even need to justify it. You already know why it’s awesome. For today I’m going to focus on fantastical diseases like these, while tomorrow’s post will cover more commonplace conditions.

Magic users of various stripes control energies well beyond the understanding of normal mortals. Normally these casters are well prepared to handle the energies they summon. However, if for some reason they fail to bring their spell to completion, the magical energies can be released into their body, and left to contaminate them in one way or another, often making them ill.

If for any reason a spellcaster fails to cast a spell after they’ve begun casting it, they are at risk of contracting a magical disease. The GM should roll 1d20 on the chart below. If the result is equal to or less than the level of the spell being cast, then the magic user contracts the indicated malady. If the number rolled is higher than the level of the spell which was being cast, then nothing happens (even if that number would otherwise correspond to a disease).

For example, if a sorcerer attempts to cast a 5th level spell, but is attacked and fails their concentration check, then they are at risk of becoming ill. If the GM rolls a 2, then the caster contracts “Mystic Frailty,” because 2 < 5. On the other hand, if a 6 is rolled, the caster will not contract “Energy Leak,” because 6 > 5. Unless otherwise stated, all diseases last a number of days equal to 1d4 times the level of the spell which was failed.

1 – Glitter Sniffle
2- Mystic Frailty
3- Unsteady Casting
4- School Lock
5- Reachlost
6- Energy Leak
7- Spelldraw
8- Commoner’s Disease
9- Soul Breach

Glitter Sniffle – While most magical diseases are a severe inconvenience, Glitter Sniffle is more of a nuisance. For the duration of the illness, the caster sneezes at least once every 15 minutes. When they sneeze, a glittering, glowing light effect erupts from their nose, momentarily causing a harmless flash of light. Bits of mucus continue to glow for an hour after the fact, which can leave an obvious trail if the care is not taken.

Mystic Frailty – All spells have their effects reduced by half (number of die, number of creatures, duration. Whichever is relevant). Aside from feelings of general mental weakness, the casters spells are much less impaction than they ought to be. Though the caster may put twice as much effort into their attempt to cast fireball, the flames they produce will be significantly less intense than normal.

Unsteady Casting – Magical incantations which normally seem quite simple are more difficult to understand and express. Gestures and magical words are slightly off, causing the spell’s effects to be weakened. The saving throw for all of the caster’s spells are reduced by half. Any spell which normally does not have a saving throw, gains one.

School Lock – Whichever school of spells the cater was attempting to cast from when they failed is the only school which they can cast from at all for the duration of the disease. The magical energies specific to that school have permeated the caster’s body, causing spells of any other school to become mangled, and fail. This effect counts even if the failed spell was from the universal school, or the caster’s prohibited school.

Reachlost – The ability to designate a target for a spell is a complicated one which casters must practice hard in order to perfect. The Reachlost disease completely blocks the caster’s access to the mental muscle they need in order to accomplish that feat. For the duration of this illness, spells can only be delivered as touch spells. Magical items which increase a spells range, or metamagic feats which do so, will not function.

Energy Leak – The magical energies that the caster normally holds within their bodies leak out constantly. Anytime they attempt to cast a spell, they must make a concentration check, DC 10 + [Spell Level]. If they fail, then the spell was lost, and they cannot attempt to cast it. Additionally, the leaking magic attracts many types of magical bests which can sense it. Denizens of the lower planes are particularly sensitive to this trail, often sensing it from miles away.

Spelldraw – The shifting, roiling mass of magical energy within the caster is so powerful that it draws other magic towards it. If any spell’s target is within a number of feet of the diseased caster equal to 10 * the failed spell’s level, then the caster of that spell must succeed on a concentration check (DC 10 + [Spell Level]) or that spell’s target will become the diseased caster. The diseased caster also receives no saving throws against spells while afflicted with Spelldraw.

Commoner’s Disease – Magical energies become completely inaccessible to the caster for the duration of this disease. They are unable to cast any spells whatsoever, but can still use scrolls and magical items.

Soul Breach – This is bad. The magical energies you let course through your body have somehow entwined with your soul, corrupting it. This effect does not end until it is cured, and curing it may be difficult. Each time you cast a spell while you have this disease, make a will saving throw, DC 10 + [Spell Level]. Upon failure, this corruption spreads, and the caster gains 1 negative level.

If the disease cannot be cured, the caster faces a difficult decision about what they value more: casting spells, or being alive?

*My understanding is that the disease rules found in the DMG first appeared in a simpler form in the “Blackmoor” supplement, written by Arneson.