Syndrome

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v50.14 · v0.47.05 This article is about the current version of DF. Note that some content may still need to be updated. More Info · V

A syndrome is a disease or effect that a poor, helpless creature might get through encountering certain creatures, extracts, supernatural weather, or vindictive modders. They generally cause unpleasant and frequently fatal symptoms over a short to long period of time, but some will clear up over time or with the assistance of a doctor. A Hospital is required to diagnose and potentially treat the syndrome.

An example of a syndrome in effect. This hippo did not ultimately survive the encounter despite one bite being the only injury sustained.

List of syndromes

Syndrome	Venom	Acquired	Short-term Symptoms	Long-term Symptoms	Chronic Symptoms
Adder bite	adder venom (injected)	Being bitten by an adder, giant adder or adder man	Strong pain	Swelling Blisters Nausea	None
Bark scorpion sting	bark scorpion venom (injected)	Being stung by a bark scorpion, giant bark scorpion or bark scorpion man	Strong pain	None	None
Black mamba bite	black mamba venom (injected)	Being bitten by a black mamba, giant black mamba or black mamba man	Dizziness Drowsiness Strong pain Fever Unconsciousness Complete paralysis1	None	None
Blob blisters	cave blob fluid (contact or ingested)	Touching a cave blob	Mild pain Mild blisters	None	None
Brown recluse spider bite	brown recluse spider venom (injected)	Being bitten by a brown recluse spider, giant brown recluse spider or brown recluse spider man	Nausea Fever Pain	Severe localized necrosis	None
Bumblebee sting	bumblebee venom (injected)	Being stung by a bumblebee worker	Pain Strong swelling	None	None
Bushmaster bite	bushmaster venom (injected)	Being bitten by a bushmaster, giant bushmaster or bushmaster man	Strong pain Mild bleeding Dizziness Nausea Unconsciousness Complete paralysis1	None	None
Cave floater sickness	cave floater gas (inhaled or ingested)	Expelled from cave floater	Mild nausea	Fever Strong drowsiness (delayed) Strong dizziness (delayed)	None
Cave spider bite	cave spider venom (injected)	Being bitten by a cave spider	None	None	Very mild dizziness
Copperhead snake bite	copperhead snake venom (injected)	Being bitten by a copperhead snake, giant copperhead snake or copperhead snake man	Pain Swelling Nausea	None	None
Giant cave spider bite	giant cave spider venom (injected)	Being bitten by a giant cave spider	Size-dependant paralysis.	Death by asphyxiation, in small targets. Large targets are generally unhindered...unless you count the high probability of being eaten by the giant cave spider as a hindrance.	None, not that it really matters.
Gila monster bite	gila monster venom (injected)	Being bitten by a gila monster, giant gila monster or gila monster man	Pain Mild swelling	None	None
Gnomeblight	gnomeblight (contact, inhaled, injected, or ingested)	Unknown. Affects gnomes only	None	Severe systemic necrosis2	None
Giant desert scorpion sting	giant desert scorpion venom (injected)	Being stung by a giant desert scorpion	Necrosis of the brain and nervous system	Certain death	None, not that it really matters.
Helmet snake bite	helmet snake venom (injected)	Being bitten by a helmet snake	Minor bleeding	Fever Nausea Dizziness Localized swelling Localized oozing Localized bruising Strong pain Intense localized necrosis Possible loss of limb	None
Honey bee sting	honey bee venom (injected)	Being stung by a honey bee worker	Pain Strong swelling	None	None
Inebriation	Alcohol (consumed/injected)	Being served drinks in a Tavern	Nausea Dizziness Unconsciousness Personality changes Euphoria Erratic behavior Trouble breathing	None	None
Iron man cough	iron man gas (inhaled)	Expelled by iron man	Coughing blood	None	None
King cobra bite	king cobra venom (injected)	Being bitten by a king cobra	Complete paralysis1 Pain, dizziness, drowsiness	None	None
Phantom spider bite	phantom spider venom (injected)	Being bitten by a phantom spider	None	Numbness and mild dizziness	None
Platypus sting	platypus venom (injected)	Being kicked by a platypus, giant platypus or platypus man	Pain and swelling	Extreme pain, swelling possibly to the point of necrosis	None
Rattlesnake bite	rattlesnake venom (injected)	Being bitten by a rattlesnake, giant rattlesnake or rattlesnake man	Pain, nausea, blisters, swelling, bruising	Severe localized necrosis	None
Serpent man bite	serpent man venom (injected)	Being bitten by a serpent man	Complete paralysis1	None	None
[evil rain] sickness3	Random	Being caught outside in freakish weather in an evil biome	Random	Random	Random
[evil cloud] sickness4		Being caught in a creeping cloud in an evil biome
beast sickness5		Encounters with forgotten beasts
titan sickness5		Encounters with titans
demon sickness5		Encounters with demons

1. For small creatures such as humans and dwarves, paralysis tends to result in suffocation.

2. Necrosis of the brain will eventually result in death once the brain rots away completely.

3. Evil rain typically only causes minor symptoms such as blisters, bruising, coughing blood, dizziness, fever, nausea, oozing, and pain.

4. Evil clouds either cause major symptoms (as with beast/titan/demon sicknesses) or permanently transform creatures into zombie-like forms.

5. Titans, forgotten beasts, and demons have a chance to have a randomized syndrome. These range from pointless (mild blisters from inhaling boiling blood) to instantly fatal (severe necrosis from a contact poison attached to a breath weapon/creature made of blood).

The anatomy of a syndrome

Mechanically, syndromes are bundles of tokens attached to a material - they're confined to creature materials in vanilla DF, but it's a simple matter to add them to inorganic materials. When the material is injected, touched, inhaled, or ingested (depending on the syndrome), the creature suffers the predations of a nasty disease or poison. Here's an example syndrome, taken from the Giant Cave Spider raws.

If you are having troubles getting the syndromes to work (i.e., in combat reports, getting "supersnake n/a splatters~etc"), then simply throw the venom template into the actual creature's raw, which is what the LOCAL_CREATURE_MAT actually calls on; the venom being in the same file.

   [USE_MATERIAL_TEMPLATE:VENOM:CREATURE_EXTRACT_TEMPLATE]
       [STATE_NAME:ALL_SOLID:frozen giant cave spider venom]
       [STATE_ADJ:ALL_SOLID:frozen giant cave spider venom]
       [STATE_NAME:LIQUID:giant cave spider venom]
       [STATE_ADJ:LIQUID:giant cave spider venom]
       [STATE_NAME:GAS:boiling giant cave spider venom]
       [STATE_ADJ:GAS:boiling giant cave spider venom]
       [PREFIX:NONE]
       [ENTERS_BLOOD]
       [SYNDROME]
           [SYN_NAME:giant cave spider bite]
           [SYN_AFFECTED_CLASS:GENERAL_POISON]
           [SYN_IMMUNE_CREATURE:SPIDER_CAVE:ALL]
           [SYN_INJECTED]
           [CE_PARALYSIS:SEV:100:PROB:100:RESISTABLE:SIZE_DILUTES:START:5:PEAK:10:END:20]

The first line, USE_MATERIAL_TEMPLATE, is creating a new material, called POISON, using the CREATURE_EXTRACT_TEMPLATE as the basis. After this, the STATE_NAME and STATE_ADJ tokens are used to define the names and adjectives assigned to different states of the material - GAS, LIQUID and ALL_SOLID, in this case, though ALL is also a valid token. At this stage, you can use any material tags like MAT_FIXED_TEMP or similar to set further material properties, though this usually isn't necessary.

 ENTERS_BLOOD

This tag determines whether a poison enters the blood or not. If it is not included, the poison will splatter (if liquid) or flow (if gas) over the affected body part instead when injected. If you're using a contact poison, leave this out. Necessary for injected poisons.

 SYNDROME

This tag ends the material details and begins the definition of the actual syndrome.

 SYN_NAME

This one is self-explanatory - the name of the syndrome as it will appear in-game.

 SYN_AFFECTED_CLASS

This token defines what CREATURE_CLASS will be affected by the syndrome. Most creatures are classed under GENERAL_POISON. Multiple tokens can be used in a single syndrome.

 SYN_IMMUNE_CLASS

As above, but makes class immune.

 SYN_IMMUNE_CREATURE

This token defines which creatures CANNOT be affected by the syndrome - useful for addressing specific instances within a population, such as a specific caste or an individual creature that falls under GENERAL_POISON. Syntax is [SYN_IMMUNE_CREATURE:creature:caste]. ALL can be used for the caste.

 SYN_AFFECTED_CREATURE

As above, but makes creature or caste susceptible.

 SYN_CLASS

This tag sets a class for the syndrome that can be used in interactions.

 SYN_IDENTIFIERv0.42.01.

Similar to SYN_CLASS, this sets an identifier that can be shared between multiple syndromes, for use with the SYNDROME_DILUTION_FACTOR creature token. In vanilla DF, this is used to allow dwarves to drink more alcohol before becoming inebriated.

 SYN_NO_HOSPITALv0.42.01.

Probably prevents affected dwarves from being carried to the hospital.^[Verify]

 SYN_CONCENTRATION_ADDED:x:xv0.42.01.

Repeated exposure to the syndrome will result in the effects becoming more intense. In vanilla [SYN_CONCENTRATION_ADDED:100:1000] is used with alcohol.

 SYN_INJECTED, SYN_CONTACT, SYN_INHALED, SYN_INGESTED

This token determines the method of infection - injected syndromes must be injected via a creature attack, while contact syndromes result from any contamination of a creature by material splatter (such as blood), inhaled syndromes must be inhaled in gaseous form (such as from boiling or a creature breath attack), and ingestion syndromes must be eaten or drunk. Any combination of these tags can be used. A fun variation on the usual creature injection routine is to create a material with a SYN_CONTACT syndrome and have a creature use it for blood - this tends to end poorly for any predator that chooses to attack them.

 [SPECIALATTACK_INJECT_EXTRACT:LOCAL_CREATURE_MAT:VENOM:LIQUID:100:100]

This is one method for getting a poison into a creature. If [ENTERS_BLOOD] is applied, it will be injected into the bloodstream. Otherwise, it will just splatter over the area. Put this on a creature attack. Substance type (gas, liquid, solid) does not appear to have an effect. The numbers on the end are minimum and maximum.

CE_X, or creature effect tokens, are the real meat and bones of your syndrome. They're detailed below.

Creature effect tokens

Each and every syndrome has a number of creature effect tokens, represented by CE_X - these lovely little beauties determine exactly how the poor creature suffering from the syndrome is affected. An example CE token is as follows:

 [CE_NECROSIS:SEV:100:PROB:100:LOCALIZED:VASCULAR_ONLY:RESISTABLE:START:50:PEAK:1000:END:2000]

In this example, we have an effect that will always cause severe necrosis in whichever bodypart it touches, so long as that bodypart is vascular and that the creature is not able to resist it in some manner. The effect begins shortly after the syndrome is contracted, peaks 1000 time units afterwards, and finally ceases another 1000 time units later.

As a general rule of thumb, so long as CE_X starts the string and START/(PEAK/END) end it, the order of the intervening tokens isn't important. PEAK and END aren't required.

• CE_X

The effect type. This can be a number of different tokens, as detailed in the table below this list.

• SEV:X

The severity of the effect. Higher values appear to be worse, with SEV:1000 CE_NECROSIS causing a part to near-instantly become rotten.

• PROB:X

The probability of the effect actually manifesting in the victim, as a percentage. 100 means always, 1 means a 1 in 100 chance.

• LOCALIZED (Overwrites BP tokens)

This tag causes an effect to ignore all BP tokens and then forces the game to attempt to apply the effect to the limb that came into contact with the contagion - i.e. the part that was bitten by the creature injecting the syndrome material, or the one that was splattered by a contact contagion. If an effect can not be applied to the contacted limb (such as IMPAIR_FUNCTION on a non-organ) then this token makes the syndrome have no effect. This token also makes inhaled syndromes have no effect.

• BP:BODY_PART:TISSUE (Overwritten by LOCALIZED)

Specifies which body parts and tissues are to be affected by the syndrome. BODY_PART can be BY_CATEGORY:x to target body parts with a matching [CATEGORY:x] body token (or ALL to affect everything), BY_TYPE:x to target body parts having a particular type (UPPERBODY, LOWERBODY, HEAD, GRASP, or STANCE), or BY_TOKEN:x to target individual body parts by their ID (as specified in the [BP] token). For example, if you wanted to target the lungs of a creature, you would use BP:BY_CATEGORY:LUNG:ALL. The syndrome would act on all bodyparts within the creature with the CATEGORY tag LUNG and affect all tissue layers. For another example, say you wanted to cause the skin to rot off a creature - you could use BP:BY_CATEGORY:ALL:SKIN, targeting the SKIN tissue on all bodyparts. Multiple targets can be given in one syndrome by placing the BP tokens end to end. This is one of the most powerful and useful aspects of the syndrome system, as it allows you to selectively target bodyparts relevant to the contagion, like lungs for coal dust inhalation, or the eyes for exposure to an acid gas. Not everything takes a target!

• VASCULAR_ONLY (Optional)

This syndrome only affects tissue layers with the VASCULAR token.

• MUSCULAR_ONLY (Optional)

This syndrome only affects tissue layers with the MUSCULAR token. Are you seeing a trend here?

• SIZE_DILUTES (Optional)

This token presumably causes the effects of the syndrome to scale with the size of the creature compared to the size of the dose of contagion they received, but has yet to be extensively tested.

• SIZE_DELAYS (Optional)

As above, this token has yet to be tested but presumably delays the onset of a syndrome according to the size of the victim.

• DWF_STRETCH:X^v0.42.01 (Optional)

Multiplies the duration of the syndrome by X in Fortress mode.

• ABRUPT^v0.42.01 (Optional)

Makes the symptom begin immediately rather than ramping up.^[Verify]

• CAN_BE_HIDDEN (Optional)

Can be hidden by a unit assuming a secret identity, such as a vampire.^[Verify]

The details of this table are still being thrashed out by modders, so if you have anything to add, please don't hesitate to hit the edit button!

Non-targeted syndromes will ignore any BP tokens and LOCALIZED tokens.

Token	Accepts Target	Description
CE_BLEEDING	Yes	Causes the targeted bodypart to start bleeding, with heavy enough bleeding resulting in the death of the sufferer. Some conditions seem to cause bleeding to be fatal no matter how weak.
CE_BLISTERS	Yes	Covers the targeted bodypart with blisters.
CE_BRUISING	Yes	Causes the targeted bodypart to undergo bruising.
CE_IMPAIR_FUNCTION	Yes	An organ afflicted with this CE is rendered inoperable - for example, if both lungs are impaired the creature can't breathe and will suffocate. This token only affects organs, not limbs. Note that this effect is currently bugged, and will not "turn off" until the creature receives a wound to cause its body parts to update.
CE_NECROSIS	Yes	Causes the targeted bodypart to rot, with associated tissue damage, miasma emission and bleeding. The victim slowly bleeds to death if the wound is not treated. Badly necrotic limbs will require amputation.
CE_NUMBNESS	Yes	Causes numbness in the affected body part, blocking pain. Extreme numbness may lead to sensory nerve damage.
CE_OOZING	Yes	Causes pus to ooze from the afflicted bodypart.
CE_PAIN	Yes	Afflicts the targeted bodypart with intense pain.
CE_PARALYSIS	Yes	Causes paralysis. Paralysis is complete paralysis and will cause suffocation in smaller creatures. Paralysis on a limb may lead to motor nerve damage.
CE_SWELLING	Yes	Causes the targeted bodypart to swell up. Extreme swelling may lead to necrosis.
CE_COUGH_BLOOD	No	This effect results in the sufferer periodically coughing blood, which stains the tile they're on and requires cleanup. It doesn't appear to be lethal, but may cause minor bleeding damage.
CE_DIZZINESS	No	Inflicts the Dizziness condition, occasional fainting and a general slowdown in movement and work speed.
CE_DROWSINESS	No	Causes the Drowsiness condition.
CE_FEVER	No	Causes the Fever condition.
CE_NAUSEA	No	Causes the Nausea condition, and heavy vomiting. Can eventually lead to dehydration and death.
CE_UNCONSCIOUSNESS	No	Renders unconscious.
CE_VOMIT_BLOOD	No	This effect results in the sufferer periodically vomiting blood, which stains the tile they're on and requires cleanup. It doesn't appear to be lethal, but may cause minor bleeding damage.
CE_ERRATIC_BEHAVIORv0.42.01	No	Causes erratic behavior.

Special Effects

Several special syndrome effects take different arguments than the above. These are used for generated interactions in unmodded games, but may be used as well for any substance or custom interaction.

Token	Accepts Target	Arguments	Description
CE_ADD_TAG	No	tags	Adds a tag to the affected creature. Many arguments can be used sequentially within one syndrome token. See the Interaction token IT_REQUIRES for valid tags.
CE_REMOVE_TAG	No	tags	Removes a tag from a creature. Supported arguments are the same as CE_ADD_TAG.
CE_DISPLAY_TILE	No	TILE:tile number:colour	The creature displays the specified tile and colour instead of its normal one.
CE_DISPLAY_NAME	No	NAME:singular:plural:adjective	Attaches a specified name to the creature's normal name.
CE_FLASH_TILE	No	TILE:tile number:colour:FREQUENCY:ticks default tile:ticks syndrome tile	The creature flashes between its normal tile and the one specified here.
CE_PHYS_ATT_CHANGE	No	Attribute:percentage:fixed boost(?)	Alters the physical attributes of a creature.
CE_MENT_ATT_CHANGE	No	Attribute:percentage:fixed boost(?)	Alters the mental attributes of a creature.
CE_BODY_APPEARANCE_MODIFIER	No	APPEARANCE_MODIFIER:HEIGHT/LENGTH/BROADNESS:percentage(?)	Alters the size of the creature.
CE_BP_APPEARANCE_MODIFIER	Yes	body part:APPEARANCE_MODIFIER:attribute:number]	Alters the characteristics (height, width etc.) of a body part.
CE_MATERIAL_FORCE_MULTIPLIER	No	MAT_MULT:material:A:B	Makes creature affected by materials more or less by a factor of A/B. If A is 3 and B is 2, the creature will be 1.5x weaker to the defined material (can be NONE:NONE for all); if 2:3, the creature will be 1.5 times stronger.
CE_BODY_MAT_INTERACTION	No		Causes one of the creature's materials to trigger an interaction, generally when ingested. Several additional tokens may be specified after this: CE:INTERACTION:interaction_id CE:SYNDROME_TAG:syndrome_trigger_type (SYN_INGESTED, SYN_INJECTED, etc.)
CE_SPEED_CHANGE	No	speed modifier:number	Changes the speed of a creature. Speed modifier contains one or both: SPEED_PERC:percentage (this modifies a creature's in-game speed, so higher numbers are faster) SPEED_ADD:number (this modifies a creature's [SPEED:XX] token, so higher numbers are slower. Negative numbers are accepted though will only reduce a creature's speed to zero) The minimum and maximum speeds able to be created by CE_SPEED_CHANGE are 99 and 10,000 respectively.
CE_CAN_DO_INTERACTION	No		Makes the creature able to perform an interaction. See Interaction token. To specify the interaction, use the argument: CDI:INTERACTION:interaction name
CE_BODY_TRANSFORMATION	No	PROB:percentage:START:time:END:time	Transforms into another creature. PROB and END arguments optional. The target creature is specified with: CE:CREATURE:CREATURE_ID:CASTE_ID (ex. CE:CREATURE:DWARF:FEMALE) Note that any wounds the creature has suffered will instantly heal upon transforming, both into and out of the target form. Undead limbs of a creature with this token will grow into a full instance of that creature.
CE_SKILL_ROLL_ADJUST	No	PERC:percentage:PERC_ON:percentage	Alters the skill level of a creature. The argument PERC specifies a percentage of the creature's current skill, and PERC_ON the probability of the effect being applied on a particular roll.
CE_SENSE_CREATURE_CLASS	No	CLASS:creature class:tile:color	Allows creature to see other creatures with given class through walls. Vampires, for example, have CLASS:GENERAL_POISON:15:4:0:1.
CE_CHANGE_PERSONALITYv0.42.01	No	FACET:trait:amount	Changes a personality trait by amount. Multiple FACET:trait:amount sets may be used.
CE_FEEL_EMOTIONv0.42.01	No	EMOTION:emotion	Makes the creature feel specific emotion; severity based on standard SEV value. The thought the creature receives is: "[creature] feels [emotion] due to [syndrome name]". See Emotion for the list of valid emotions.

All creature effect tokens take START, END and PROB numbers, and can be followed by [CE:PERIODIC] and/or [CE:COUNTER_TRIGGER] to restrict when they actually take effect.

• PERIODIC:period_type:min_value:max_value
• COUNTER_TRIGGER:counter_name:min_value:max_value:REQUIRED

Currently, the only valid period type is MOON_PHASE.

Counter Triggers

Valid counter values are below:

Counter	Description
ALCOHOLIC	How long it's been (in time units) since the creature last had a drink of alcohol. Only present on creatures who need alcohol to get through the working day. 100800 (3 months) = and is starting to work slowly due to its scarcity 201600 (6 months) = and really wants a drink 302400 (9 months) = and has gone without a drink for far, far too long 403200 (1 year) = and can't even remember the last time he/she had some
MOUNTAIN	How much the creature minds being outdoors. Low values are known to decrease the severity of certain unhappy thoughts. 0 = likes working outdoors and grumbles only mildly at inclement weather. 1 = does not mind being outdoors, at least for a time. 2 = (no message)
TIME_SINCE_BREAK	How long it's been (in time units) since the creature last went on break. Creatures generally go at least a year (100800 time units) between breaks unless the economy is active (which never happens).
ON_BREAK	How long (in time units) the creature has been on break. Once it reaches 15000 (about 12.5 days), the creature should get back to work.
CAVE_ADAPT	How cave-adapted the creature is. Increases by 1 for every time unit spent underground, to a maximum of 800000. 403200 (1 year) = going outside causes irritation 604800 (1.5 years) = going outside causes nausea
PARTIED_OUT	How long before the creature will decide to attend another party. Starts at 3+ months and counts down to zero.
MILK_COUNTER	How long before the creature can be milked again. Starts at the creature's MILK frequency and counts down to zero.
EGG_SPENT	How long before the creature can lay more eggs. Starts at 3 months and counts down to zero.
GROUNDED_ANIMAL_ANGER	How angry (and likely to attack) an animal is from being over-crowded. Increases when over-crowded and otherwise counts down to zero.
TIME_SINCE_SUCKED_BLOOD	How long it's been (in time units) since the creature last sucked somebody's blood.
DRINKING_BLOOD	How much longer the creature will be drinking somebody's blood. Starts at 2.4 days and counts down to zero.

Inorganic syndromes and you!

It's perfectly possible - and quite simple - to add a nasty syndrome to a type of rock or metal - you simply add the syndrome tokens to the material definition in the same manner that you would add them to a creature material definition. The only catch is that since your hapless dwarves will only normally encounter the material in metal, gem or boulder form, a bit of creativity must be used to actually get them inside your citizens - that is, you need to make them 'explosively boil' as soon as they're mined or produced. This has the sad side effect of destroying the actual item - sorry, no highly radioactive uranium this release.

The easiest way to accomplish this is to assign the material a low boiling point, usually just under room temperature, and make sure its temperature is fixed to a point above it.

 [MELTING_POINT:NONE]
 [BOILING_POINT:10000]
 [MAT_FIXED_TEMP:10001]

Now, as soon as this substance hits the open air - by being mined, smelted or reaction-produced at a custom workshop - it will EXPLOSIVELY BOIL, flooding a small area with delicious syndrome-rich gas. Creatures who inhale the gas will be immediately hit with the syndrome you thoughtfully attached to the material definition earlier!

There are a number of other tokens you can use to control the colour and naming conventions of your syndrome material, referred to as material definition tokens.

Spreading diseases

It is fully possible to make a nasty disease capable of spreading itself from an infected dwarf to others, though it requires some skill in modding interactions as well. Here is an example of a plague-inflicting interaction:

 [INTERACTION:PLAGUE]
 	[I_TARGET:A:CREATURE]
 		[IT_LOCATION:CONTEXT_CREATURE]
 		[IT_FORBIDDEN:NOT_LIVING]
 		[IT_AFFECTED_CLASS:GENERAL_POISON]
 		[IT_MANUAL_INPUT:creatures]
 	[I_EFFECT:ADD_SYNDROME]
 		[IE_TARGET:A]
 		[IE_IMMEDIATE]
 		[SYNDROME]
 			[SYN_NAME:the plague]
 			[SYN_AFFECTED_CLASS:GENERAL_POISON]
 			[CE_FEVER:SEV:250:PROB:100:START:250:PEAK:1500:END:25000]
 			[CE_BLISTERS:SEV:325:PROB:100:BP:BY_CATEGORY:ALL:SKIN:START:250:PEAK:1500:END:25000]
 			[CE_NECROSIS:SEV:300:PROB:100:BP:BY_CATEGORY:ALL:ALL:VASCULAR_ONLY:START:22500:PEAK:23750:END:25000]
 			[CE_CAN_DO_INTERACTION:START:1500:END:25000]
 				[CDI:ADV_NAME:Spread the plague]
 				[CDI:INTERACTION:PLAGUE]
 				[CDI:TARGET:A:LINE_OF_SIGHT]
 				[CDI:TARGET_RANGE:A:10]
 				[CDI:WAIT_PERIOD:30]

As you can see, the syndrome here inflicts blisters, fever and, after roughly a month, necrosis of the whole body. That's when the infected creatures will start dying out. But before that happens, CE_CAN_DO_INTERACTION makes them capable of spreading the plague further.

You also need a disease vector that will bring the plague straight to your fort. (hint: use various species of rats - they're perfect for that). The following code, added to creature's raws, ensures the creature will infect anybody it encounters:

 [CAN_DO_INTERACTION:PLAGUE]
 	[CDI:ADV_NAME:Spread the plague]
 	[CDI:TARGET:A:LINE_OF_SIGHT]
 	[CDI:TARGET_RANGE:A:10]
 	[CDI:WAIT_PERIOD:30]

As soon as the said creature is startled by your dwarves, the fun will begin.