Disease Model

[Lord God Jinnai]

Here's the thing (my assumption from the way it was explained).

Ok you start out with X strains. Each with differnt strengths. Well just because a culture is resistant to 1 strain doesn't ness make it resistant to another. Influensa in a good example because every year people have to get new shots for all the new strains that developed because they may not be resistant to the new ones, but still be so for the older ones.

Another thing is that although strains are usually more powerful, they sometimes aren't.

[Theben]

One thing I didn't see (I admit to skimming over it) is separating "crowd" diseases (the epidemic-causing ones) from other diseases. These generally need a minimum population to maintain the disease (FE, measles requires 500,000 people in a locale in order to establish itself and not die out of that pop) and come from domesticated animals. Native Americans didn't have too many crowd diseases because of their dearth of domestic animals.

I also didn't see anything about a total lack of immunity when new contact between civs is made (as in old world meets new world diseases). Mortality rates in these cases have been known to be as high as 98%. This might ruin the game from a player's standpoint, though.

Epidemics that occur in pops with descent medicine, etc. may still run rampant. The influenza epidemic at the end of WWI in the U.S. killed 21 million people (although I don't think all the resources of the nation went to help these people, generally poor immigrants). Wiil you have random events in Clash, that this could fall under? Or would this also be too much for the average player?

Diseases are also subject to natural selection. One that is too weak will not establish itself in a host body, while one that is too powerful will kill its host too quickly for it to pass to another host, and not become established in a pop. Eventually any given disease tends to move towards the middle, allowing us to live long enough to pass our infection along to another human. I feel that this is what you're trying to accomplish with the "strains", but IMHO there should be an easier way to model diseases establishing themselves permanently in a popualtion w/o excess details.

Lastly, I have a disease model in the civ3 forums (under Miscellaneous/other in the "List")that you can feel free to look at. It needs updating, though. And read "Guns, Germs, and Steel" by Jared Diamond if you haven't yet (where I got most of my info)!

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Theben
Co-Moderator of the Civ3 Forums



[This message has been edited by Theben (edited January 10, 2000).]

[alms66]

I've been thinking about the strains... and Mark may be right, we don't need them. For instance LGJ's example of the Influenza, Look at the Mortality rate, it's 1-20%, which simulates the varying strength of disease strain. With the new write-up on how disease works and this I think we can do without strains.

Also I think I solved the geographical distribution of diseases problem. First there is the random seed method. But the next version I post will include something similar to the previous but include geographic separation too. I'll be working on a new version of this and the Disaster model for the next few days. So expect it soon.

Also I'd like to say we should wait to impliment disease and disasters until all the other models are working good. Simply because of the randomness of such things, I just thought it would be best to save them for last.

[Krenske]

I would just like to make a slightly off topic suggestion. A multinational wonder called disease irradication. When a tech for international medical cooperation is learnt there should be a general health improvement, but a new wonder should become available. The option should exist for starting a "world wonder" that will eliminate a disease. As an example I give Smallpox. (According to the US Surgeon General and WHO we came very close to wiping out malaria as well but the program was terminated because it ran over budget. There were some initial murmurings about the DDT in use as well but this was before any real ECO backlash. Talk about administrative insanity!!)

The benefits would obviously be the elimination of the disease but would also include a diplomatic improvement for the major contributors. A happiness improvement for a period of time should also be considered.

Hows that?
[This message has been edited by Krenske (edited January 18, 2000).]

[Lord God Jinnai]

TK:

Not that i'm saying u have to use strains but how will u model the following situation (i will be using strains for the example so u can tell how to do it without):

Influenza Strain 1 in egypt
Influenza Strain 2 in greece

The egyptians are resitant to strain 1 but not strain 2 and vise versa.

They meet and combine to form strain 3, which is more powerful (this part has been explained well enough). Strain 3 then exists alongside 1 and two.

The Persains didn't start out with influenza (kinda unrealistic considering the geographic relationship but its only an example). Instead the egyptian strain was brought to them. Since the persians never had influenza they'd have a low resistance (again this part has been adequetly figured out). Now because the persians are slightly differnt from the egyptians aftern X turns they strain mutates into strain 4.

Quick Recap:

Strain 1: Greece
Strain 2: Egypt
Strain 3: Greece & Egypt (Hybrid)
Strain 4: Persia (Mutated Egypt Strain).

Now in order the resistance comparison of all the cultures, from most resistant to least:

Egypt: 2, 4, 1, 3
Greece: 1, 2, 3, 4
Perisa: 2, 3, 4, 1

Finnaly sveral years have gone by and after much mixing of blood and such. The earlier strain will almost always be weaker than earlier strains so strain 3, after it once again evolves to suit the egyptian population and becomes strain 5. If strain 5 goes to persia at the same tome the little that's left of strain 2 does, strain 5 will have a much better chance of floursishing than strain 2, which probably wouldn't at all.

Eventually strain 1 and 2 may become extinct (as well as the others) but the thing is although the diseases continue to increase in potency, the increase in potency only to that culture and a strain from another culture vastly differnt would usually have much more drastic effects, even if its the same disease.

If u can come up with a model that does that without strains i'm all for it.

Krenske:

First off it should be put in the wonders formum, imo since thats where all talk of wonders is. Anyway there was talk about that type of wonder (check it out urself) but i really don't it should be a "wonder" because then everyone would try to eliminate all diseases and then what would happen to poor TK's model (sarcastic)
[This message has been edited by Lord God Jinnai (edited January 18, 2000).]

[Mark_Everson]

TK:

I'm with you on all three points. If you get to the point where you've done all you think you can on diseases and natural disasters until the other models are further along, just let me know! I'm sure we can find additional productive work for you to do

Krenske:

That's a Very Cool idea! It would especially give the Builder types who don't much like to fight something more to shoot for at the end of the game.

[alms66]

I like Krenske's idea about the "wonder" although I wouldn't call it a wonder either. However it should still be a monumental undertaking (in addition to alot of $$$!).

Strains:
LGJ brings up a few points I hadn't even considered about them and also seems to understand what I wrote about them alot better than I do! So until we get more opinions on it other than just LGJ, Mark and myself I'll leave them in.

OFF TOPIC: I think we should include more polls, maybe a vote could put the strain debate (and alot of others) to rest, allowing the designers to do more work on the models.

[Henrique Duarte]

There is an important aspect in civilization evolution that has not been considered.
The agricultural "knowledge" trade. I believe the traditional tech approach is inappropriate and the reason I think so lead me to this disease model thread(Which I think is quite important to do a good simulation of civs.)

The reason is: croop diversity and diffusion is quite similar to the disease spreading being modelled in with this strain approach.
When Cultures of different geographic origins (here the geography and not etnography is important) achieve contact one of the first things to switch hands are desieses and croop knowledge (Potatoe :-).
The efficiency of this trade will depend on the ability to produce the crop in the homeland (if you have favourable climate you use the crop and produce more, if not you drop it)
Large geographically diversified regions with plenty of internal culture contacts achieved higher agricultural productivity indexes (Europe+Asia) than regions with either climateric barriers (Africa with several climateric regions from north to south) or geological and geographical limitations (North and South America have limited East-West dimensions which limit the crop development)

Now how to make this use of this in gameplay. Get something like the strain model into croop exchange; there would be great agricultural bonus in the first croop exchanges and they would decrease with further exchanges (this would be both realistic and fun to play because you would get civilizations like the Meso-Americans to develop despite somewhat limited crop diversity, encourage isolated cultures to establish contact with other groups, no hiding and achieving space tech for small island civs; this would also give a little bonus to the cultures that are allways banging heads with someone else because they are in the geographical center of global politics.

There is a book that gets deep into this subject called something like "germs, guns and butter" (don´t remember the author) if you want to get a better idea of what I am trying to say

[alms66]

Henrique Duarte,
I would say that you've got a pretty good idea of how you would like it to be done. I personally would like to include it just because I want this game to be a realistic as possible. So why don't you write up a model and we can discuss it from there.

[Henrique Duarte]

Toubabo

I´ll take a shot at modeling this idea.
will send it to you so that you may do lots of "constructive criticism" :-))

Henrique

[alms66]

Disease Table Mortality Real World
Disease / rate / Location
Bubonic Plague / B / 15-30% / plains near India
^Cholera / B / 10-20% / Arabia
^Dysentery / B / 10-20% / Most likely Africa
$Dengue Fever / V / 10-20% / Most likely Africa
^Diphtheria / B / 5-10% / Most likely Africa
$Ebola / V / 15-30% / African jungles
Hantavirus / V / 15-30% / plains near India
$HIV/AIDS / V / 1-5% / African jungles
Influenza / V / 1-20% / Europe
Leprosy / B / 1-2% / Arabia
$Malaria / V / 5-10% / African jungles
Measles / V / 1-5% / Arabia/Egypt
$Sleeping Sickness / V / 5-10% / African jungles
Smallpox / V / 5-10% / Arabia/Egypt
Syphilis / B / 1-5% / Americas (from Caribbean believed)
^Tuberculosis / B / 5-10% / Europe
^Typhus / B / 5-10% / Europe
Whooping Cough / V / 1-5% / Europe
$Yellow Fever / V / 5-10% / Most likely Africa

*Clearly most disease came from central Africa, Egypt, Arabia or India. The only exceptions are those few diseases from Europe (The first “official” cases of the disease I could find, most of which were well beyond 1A.D., but they most likely also came from Africa and just went by a different name earlier in history.), and Syphilis which some believe came from America but this is highly disputed. This basically suggests one disease pool containing all diseases in central Africa, and they simply spread from there.

So basically what I’m suggesting is rather than random distribution of disease we use a single large disease pool. Diseases would then simply spread along with migrations, armies, explorers and trade routes, as they seem to have in the past. This I believe would simulate real world history best.

I'd like to hear what others think about this idea?

[Lord God Jinnai]

Smallpox was bacterial (this is a common misprint/myth). This is prob the only reason we destroyed it because bacterial diseases can't adapt as quickly as viruses.

As far as the single disease pool that could be okay for human diseases since that also is supported by one of the major theories of the evolution of man. There may be a few exceptions. The only thing i can think of that might contradict that idea would be that many of these diseases came from animals and adapted for human hosts. This is true with most viral diseases such as AIDS/HIV. Also some diseases in the american and asian jungles are local also. Many of these diseases only started to appear with the tearing up of these places. So what I say is that the diseases might not originate from 1 location, but should originate from tropical regions.

There is also genetically engineered diseases which don't fall under this category at all.

BTW have u anything on non-human dieseases yet?