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Disease Model v1.1
I think I managed to get all the concerns and suggestions from the previous discussion into this new version. If I missed anything please let me know.
Disease Model v1.1
The Disease Pools
Method I
To determine what diseases a culture starts with, disease pools will have to be established first. There will be an unlimited number of disease pools. The size and location of the disease pools will conform to the following criteria:
-On each continent, all cultures with similar population densities will belong to the same disease pool (if adjacent).
-Islands will belong to whichever continent it is closest to (if within the range of ancient boats, 2 spaces I presume).
-Island chains will be grouped together as a single disease pool if all islands are within ancient boat range (again, 2 spaces I presume).
Once the disease pools are established, the number of diseases in each disease pool will be established according to the following criteria:
-The number of diseases in each pool is:
Climate zone: # of diseases
Arctic/islands 0-1 (leaning toward 0, maybe a 60% chance)
Sub arctic/temp. 0-2
Subtropical /tropical 1-3
Once the number of diseases in each pool has been determined, the diseases that reside in those pools will be distributed as follows:
-Tropical pools will receive only jungle and water-borne diseases (excluding HIV and Ebola).
-Temperate pools will receive only the “normal” and water-borne diseases.
-Arctic pools will receive only “normal” diseases.
-Islands or island chains that count as a separate disease pool will get one disease (if any), and that disease will not belong to any other pool
-Diseases can be “shared” between different, adjacent pools if they still need more to fill in their number of diseases.
-Every disease that is in more than one pool will receive a strain tag (A, B, C, etc.).
Then each culture would get its number of initial diseases from its disease pool.
Initial Diseases
Initial Diseases will represent those the people have previously been exposed to. Every province of every Civ. and barbarian "Culture" in the game will start with at least one of the 19 diseases modeled in the game. This assumes that each different cluster of any barbarian culture will be treated as a different province (ex. If culture #17 were divided by Roman territory, each half would be treated as a different province). By modeling every province rather than the Civ/Culture as a whole we can allow for greater diversity and realism in the system with only a few extra calculations.
To calculate the number of initial diseases a Civ has, we would generate a number (1-10) then modify it by population density, sanitation level and climate. Climate would modify the number based on the zone the Province is located in:
Population Density (not yet determined)
Sanitation level (will include this only if it varies enough from Civ to Civ)
Climate Zone Modifier (+/-)
Sub-arctic/Arctic 2
Sub-arctic/Temperate 1 (use this if it overlapping both zones listed)
Temperate 0
Temperate/subtropical -1 (use this if it overlapping both zones listed)
Subtropical/Tropical -2
Once modified for climate zone and density, the number of diseases is as follows (however the number of diseases cannot exceed or be lower than the number in the pool):
Modified Number Number of Diseases
1 or less 3 Diseases
2-6 2 Diseases
7-10 1 Disease
More than 10 0 Diseases
Method II
The computer will generate a random location for each disease in the game. These locations (a single square, and all adjacent to it, including diagonals) will be the starting points for the disease, and they will spread from there. The locations will be generated according to the following criteria:
-Tropical squares will receive only jungle and water-borne diseases (HIV and Ebola will be inactive until later).
-Temperate squares will receive only the “normal” and water-borne diseases.
-Arctic squares will receive only “normal” diseases.
-A square can be randomly chosen more than once (i.e. have more than one disease.)
Method III
The computer will determine a location within the tropical zone within the largest landmass for a single disease pool to be located. The pool will be 12 squares “circular” and will contain all diseases. Again, HIV and Ebola will be inactive until later.
Disease Table
Key
^ = Water-borne;
$ = Jungle;
* = Ebola and HIV/AIDS are never initial diseases but come in later in the game to preserve some history to disease.
Str. Increase Codes
A = 0-2
B = 0-3
C = 1-3
D = 2-4
Disease Mortality Real World Str. Increase
Name/ viral, bacterial / rate / Location Code
Bubonic Plague / B / 15-30% / plains near India B
^Cholera / B / 10-20% / Arabia C
^Dysentery / B / 10-20% / Most likely Africa A
$Dengue Fever / V / 10-20% / Most likely Africa A
^Diphtheria / B / 5-10% / Most likely Africa A
$Ebola / V / 15-30% / African jungles D
Hantavirus / V / 15-30% / plains near India C
$HIV/AIDS / V / 1-5% / African jungles A
Influenza / V / 1-20% / Europe C
Leprosy / B / 1-2% / Arabia A
$Malaria / V / 5-10% / African jungles B
Measles / V / 1-5% / Arabia/Egypt A
$Sleeping Sickness / V / 5-10% / African jungles B
Smallpox / B / 5-10% / Arabia/Egypt B
Syphilis / B / 1-5% / America/Caribbean A
^Tuberculosis / B / 5-10% / Europe B
^Typhus / B / 5-10% / Europe B
Whooping Cough / V / 1-5% / Europe A
$Yellow Fever / V / 5-10% / Most likely Africa A
How Disease Works
For every disease a culture has it will also have a resistance number for that disease. There will also be a strength number (str.) for each disease. It is by comparing these two numbers we will determine what effects a disease will have:
-If disease str. is equal to or less than the culture's resistance:
STR % pop. Loss
Equal .05% (5 “heads” per 10 million)
1 less .04% (4 “heads” per 10 million)
2 less .03% (3 “heads” per 10 million)
3 less .02% (2 “heads” per 10 million)
4 less .01% (1 “head” per 10 million)
5+ less no loss
*The player would not be alerted to these deaths because it isn't an epidemic; it’s just the natural course of the disease. These would, however, show up in a population losses chart (that would include all causes of death, not just disease based), which the player could access, each turn if he so desires. *
-If disease str. is greater than the culture's resistance, a percentage check for an epidemic is made. This % chance is equal to 4 times the difference (may need to be adjusted during play testing) between str. and resistance.
-If there is an epidemic, there is a loss of population equal to the mortality rate generated for the disease plus the difference between resistance and disease str. This loss is for one turn only!
Some other things to keep in mind:
-Base resistance is 0 for all diseases, except initial diseases, which are 10.
-Base disease str. is 5 plus the code (A, B, C or D) increase.
-When an epidemic occurs, resistance increases by 1-5
-Disease str. increases by the amount listed for its str. increase code whenever pop. density increases and/or sanitation levels decrease.
-With the discovery of genetic engineering a civ could create new diseases or more powerful strains of existing diseases for use in biological warfare. We do need to make sure that the AI for other civs “understands” the risks associated with this. They would be just as susceptible to the engineered disease also, unless they made themselves a cure first…
Spreading Disease
Whenever any kind of contact is made between two civs/cultures (merchants, armies, migrations, etc.) there would be a 10% chance of the disease spreading. Also when a unit encounters jungle, there will be a 5% chance of it catching a jungle disease and possibly bringing it back to its homeland.
Ebola and Aids will have a 5% (just as any other jungle disease) chance of infecting anyone who travels in the jungle, however only after whatever turn the year 1900 (maybe even later) occurs on.
When contact occurs, including jungle travel, add 5% per head to the chance of catching a disease.
Other Modifiers
-Infrastructure could help reduce casualties of disease.
-Famine will reduce resistance temporarily, while famine continues, by -3 per turn (cumulative).
-Technology- some will have individual effects on diseases, chance of spreading or Mortality rates (like vaccinations will cure some diseases).
-Overcrowding, poor sanitation, poor nutrition, and water supply reduces resistance
-Some techs will increase the rate of disease str. increases (for example: vaccinations will cause viral diseases to “evolve” at a faster rate, creating super diseases).
Eradicating Disease
Krenske proposed this multinational “wonder” and I think it is a great idea. However, I don’t see it as a wonder so this is what I propose:
A treaty only allowed under the United Nations, simply because most countries, I think, would not allow the large amount of people necessary to complete the task into their country for whatever reason. So with the U.N. backing the treaty a disease could be eradicated throughout the world, as smallpox was in real life.
To accomplish this at least one nation would have to have a medical tech level of a certain level (TBD), and the project would also cost lots of money for supplies, etc., along with a number of turns based on the population of the planet at that time. There are still a few details to add to this but I think everyone should get the idea. What do you think?
Strains
After much thought on the subject, I’d have to say the best thing to do is to model disease without strains and see how it works. If it’s great as is, then leave the strains out. But if the model lacks that certain “flare” we could later spice it up with strains. But I’ll leave the basics here just in case.
Each disease will have several strains active until sufficient contact has turned it into a single strain. An example would best explain this:
The Greeks have smallpox (strain one) and the Egyptians have smallpox also (but strain two). Upon contact & transfer of both strains between the 2 civs, there would be a flare-up (+10 to disease str. for one turn) of the disease as the two disease pools collide and meet new cultures. Then these two strains would be annialated and would become strain three (a new strain) within both civs.
Now if the Greeks had given the Romans strain 1 previously but no longer had contact with them, strain 1 would become strain 4 when the Greeks and Egyptians met and created strain three (strains one and two would be annialated).
The player would never see strains; they would only help simulate flare-ups of disease as disease pools collide. They would also simulate a decrease in flare-ups as sufficient contacts are made between cultures thereby increasing the size of the disease pools.
Agricultural Disease
Agricultural Disease, I believe, would best be handled as a certain percentage lost to disease each turn (rather than a complicated model) with techs like pesticides reducing this %, simply because it will really only affect food production, unless we use limited timber resources.
[This message has been edited by Toubabo_Koomi (edited February 03, 2000).]
Disease Model v1.1
The Disease Pools
Method I
To determine what diseases a culture starts with, disease pools will have to be established first. There will be an unlimited number of disease pools. The size and location of the disease pools will conform to the following criteria:
-On each continent, all cultures with similar population densities will belong to the same disease pool (if adjacent).
-Islands will belong to whichever continent it is closest to (if within the range of ancient boats, 2 spaces I presume).
-Island chains will be grouped together as a single disease pool if all islands are within ancient boat range (again, 2 spaces I presume).
Once the disease pools are established, the number of diseases in each disease pool will be established according to the following criteria:
-The number of diseases in each pool is:
Climate zone: # of diseases
Arctic/islands 0-1 (leaning toward 0, maybe a 60% chance)
Sub arctic/temp. 0-2
Subtropical /tropical 1-3
Once the number of diseases in each pool has been determined, the diseases that reside in those pools will be distributed as follows:
-Tropical pools will receive only jungle and water-borne diseases (excluding HIV and Ebola).
-Temperate pools will receive only the “normal” and water-borne diseases.
-Arctic pools will receive only “normal” diseases.
-Islands or island chains that count as a separate disease pool will get one disease (if any), and that disease will not belong to any other pool
-Diseases can be “shared” between different, adjacent pools if they still need more to fill in their number of diseases.
-Every disease that is in more than one pool will receive a strain tag (A, B, C, etc.).
Then each culture would get its number of initial diseases from its disease pool.
Initial Diseases
Initial Diseases will represent those the people have previously been exposed to. Every province of every Civ. and barbarian "Culture" in the game will start with at least one of the 19 diseases modeled in the game. This assumes that each different cluster of any barbarian culture will be treated as a different province (ex. If culture #17 were divided by Roman territory, each half would be treated as a different province). By modeling every province rather than the Civ/Culture as a whole we can allow for greater diversity and realism in the system with only a few extra calculations.
To calculate the number of initial diseases a Civ has, we would generate a number (1-10) then modify it by population density, sanitation level and climate. Climate would modify the number based on the zone the Province is located in:
Population Density (not yet determined)
Sanitation level (will include this only if it varies enough from Civ to Civ)
Climate Zone Modifier (+/-)
Sub-arctic/Arctic 2
Sub-arctic/Temperate 1 (use this if it overlapping both zones listed)
Temperate 0
Temperate/subtropical -1 (use this if it overlapping both zones listed)
Subtropical/Tropical -2
Once modified for climate zone and density, the number of diseases is as follows (however the number of diseases cannot exceed or be lower than the number in the pool):
Modified Number Number of Diseases
1 or less 3 Diseases
2-6 2 Diseases
7-10 1 Disease
More than 10 0 Diseases
Method II
The computer will generate a random location for each disease in the game. These locations (a single square, and all adjacent to it, including diagonals) will be the starting points for the disease, and they will spread from there. The locations will be generated according to the following criteria:
-Tropical squares will receive only jungle and water-borne diseases (HIV and Ebola will be inactive until later).
-Temperate squares will receive only the “normal” and water-borne diseases.
-Arctic squares will receive only “normal” diseases.
-A square can be randomly chosen more than once (i.e. have more than one disease.)
Method III
The computer will determine a location within the tropical zone within the largest landmass for a single disease pool to be located. The pool will be 12 squares “circular” and will contain all diseases. Again, HIV and Ebola will be inactive until later.
Disease Table
Key
^ = Water-borne;
$ = Jungle;
* = Ebola and HIV/AIDS are never initial diseases but come in later in the game to preserve some history to disease.
Str. Increase Codes
A = 0-2
B = 0-3
C = 1-3
D = 2-4
Disease Mortality Real World Str. Increase
Name/ viral, bacterial / rate / Location Code
Bubonic Plague / B / 15-30% / plains near India B
^Cholera / B / 10-20% / Arabia C
^Dysentery / B / 10-20% / Most likely Africa A
$Dengue Fever / V / 10-20% / Most likely Africa A
^Diphtheria / B / 5-10% / Most likely Africa A
$Ebola / V / 15-30% / African jungles D
Hantavirus / V / 15-30% / plains near India C
$HIV/AIDS / V / 1-5% / African jungles A
Influenza / V / 1-20% / Europe C
Leprosy / B / 1-2% / Arabia A
$Malaria / V / 5-10% / African jungles B
Measles / V / 1-5% / Arabia/Egypt A
$Sleeping Sickness / V / 5-10% / African jungles B
Smallpox / B / 5-10% / Arabia/Egypt B
Syphilis / B / 1-5% / America/Caribbean A
^Tuberculosis / B / 5-10% / Europe B
^Typhus / B / 5-10% / Europe B
Whooping Cough / V / 1-5% / Europe A
$Yellow Fever / V / 5-10% / Most likely Africa A
How Disease Works
For every disease a culture has it will also have a resistance number for that disease. There will also be a strength number (str.) for each disease. It is by comparing these two numbers we will determine what effects a disease will have:
-If disease str. is equal to or less than the culture's resistance:
STR % pop. Loss
Equal .05% (5 “heads” per 10 million)
1 less .04% (4 “heads” per 10 million)
2 less .03% (3 “heads” per 10 million)
3 less .02% (2 “heads” per 10 million)
4 less .01% (1 “head” per 10 million)
5+ less no loss
*The player would not be alerted to these deaths because it isn't an epidemic; it’s just the natural course of the disease. These would, however, show up in a population losses chart (that would include all causes of death, not just disease based), which the player could access, each turn if he so desires. *
-If disease str. is greater than the culture's resistance, a percentage check for an epidemic is made. This % chance is equal to 4 times the difference (may need to be adjusted during play testing) between str. and resistance.
-If there is an epidemic, there is a loss of population equal to the mortality rate generated for the disease plus the difference between resistance and disease str. This loss is for one turn only!
Some other things to keep in mind:
-Base resistance is 0 for all diseases, except initial diseases, which are 10.
-Base disease str. is 5 plus the code (A, B, C or D) increase.
-When an epidemic occurs, resistance increases by 1-5
-Disease str. increases by the amount listed for its str. increase code whenever pop. density increases and/or sanitation levels decrease.
-With the discovery of genetic engineering a civ could create new diseases or more powerful strains of existing diseases for use in biological warfare. We do need to make sure that the AI for other civs “understands” the risks associated with this. They would be just as susceptible to the engineered disease also, unless they made themselves a cure first…
Spreading Disease
Whenever any kind of contact is made between two civs/cultures (merchants, armies, migrations, etc.) there would be a 10% chance of the disease spreading. Also when a unit encounters jungle, there will be a 5% chance of it catching a jungle disease and possibly bringing it back to its homeland.
Ebola and Aids will have a 5% (just as any other jungle disease) chance of infecting anyone who travels in the jungle, however only after whatever turn the year 1900 (maybe even later) occurs on.
When contact occurs, including jungle travel, add 5% per head to the chance of catching a disease.
Other Modifiers
-Infrastructure could help reduce casualties of disease.
-Famine will reduce resistance temporarily, while famine continues, by -3 per turn (cumulative).
-Technology- some will have individual effects on diseases, chance of spreading or Mortality rates (like vaccinations will cure some diseases).
-Overcrowding, poor sanitation, poor nutrition, and water supply reduces resistance
-Some techs will increase the rate of disease str. increases (for example: vaccinations will cause viral diseases to “evolve” at a faster rate, creating super diseases).
Eradicating Disease
Krenske proposed this multinational “wonder” and I think it is a great idea. However, I don’t see it as a wonder so this is what I propose:
A treaty only allowed under the United Nations, simply because most countries, I think, would not allow the large amount of people necessary to complete the task into their country for whatever reason. So with the U.N. backing the treaty a disease could be eradicated throughout the world, as smallpox was in real life.
To accomplish this at least one nation would have to have a medical tech level of a certain level (TBD), and the project would also cost lots of money for supplies, etc., along with a number of turns based on the population of the planet at that time. There are still a few details to add to this but I think everyone should get the idea. What do you think?
Strains
After much thought on the subject, I’d have to say the best thing to do is to model disease without strains and see how it works. If it’s great as is, then leave the strains out. But if the model lacks that certain “flare” we could later spice it up with strains. But I’ll leave the basics here just in case.
Each disease will have several strains active until sufficient contact has turned it into a single strain. An example would best explain this:
The Greeks have smallpox (strain one) and the Egyptians have smallpox also (but strain two). Upon contact & transfer of both strains between the 2 civs, there would be a flare-up (+10 to disease str. for one turn) of the disease as the two disease pools collide and meet new cultures. Then these two strains would be annialated and would become strain three (a new strain) within both civs.
Now if the Greeks had given the Romans strain 1 previously but no longer had contact with them, strain 1 would become strain 4 when the Greeks and Egyptians met and created strain three (strains one and two would be annialated).
The player would never see strains; they would only help simulate flare-ups of disease as disease pools collide. They would also simulate a decrease in flare-ups as sufficient contacts are made between cultures thereby increasing the size of the disease pools.
Agricultural Disease
Agricultural Disease, I believe, would best be handled as a certain percentage lost to disease each turn (rather than a complicated model) with techs like pesticides reducing this %, simply because it will really only affect food production, unless we use limited timber resources.
[This message has been edited by Toubabo_Koomi (edited February 03, 2000).]
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