# Illness on Generation ship



## caters (Apr 15, 2018)

With 44000 people for genetic diversity reasons, it is inevitable that some will be ill. Now the types of illness allowed would differ.

Take viruses for instance. A cold virus like this rhinovirus:






Would be no big deal. It would just cause a cold.

Ebola on the other hand would be a huge deal because of those diagnosed, half of them die. Yes you heard me right, 50% death rate. And with there being a lot of sex going on regularly and the likelihood that someone will touch blood or urine being high, especially in children, this would spread widely and even if just 1 person had Ebola, there would be a massive die off over time. Reproduction rate would start high but as more die, the reproduction rate will drop until it is lower than the 50% death rate(in other words when teens and older comprise less than 50% of the population). Once that happens, the whole population is guaranteed to die off.

So while this might mean needing eggs and sperm of healthy people and artificial wombs as a backup, it doesn't mean that no people should be on it.

In fact, I think the worst viral infections that would be allowed are skin infections that go dormant(like chickenpox) and severe respiratory infections(pneumonia for instance). Any worse and the death rate would be too high, I think. Even the worst viral gastroenteritis wouldn't be immediately life threatening or cause a massive enough die off if transmitted for the entire population to eventually die.

Fungal is another story. A lot of fungal infections and I mean, a lot, are mild. Skin infections, vaginal yeast infections, both of those types of fungal infections are mild. Most severe fungal infections occur in people with weakened immune systems or lung disease or in those fighting another infection like a bacteria or a virus. So death rate from fungi is low, so low that I don't think fungal diseases should be restricted by severity at all. Fungal infections usually spread through direct contact or sex in the case of a vaginal yeast infection. However, sexually transmitted yeast is most likely going to give a male a UTI which can easily be treated with lots of fluids to wash away what is causing the infection. Yeast infections are also the most likely to be resistant to antifungal treatment.

So far we have this on the spectrum:





Now come the big guns. Bacteria. Just 1 group of bacteria species can cause all these illnesses:

Strep Throat
Impetigo
Scarlet fever(which is common after untreated strep throat)
Pneumonia
Toxic Shock Syndrome
Flesh Eating Disease
And these complications after the infection is over:

Acute Rheumatic fever
Rheumatic heart disease
Post-streptococcal Glomerulonephritis
So yeah, Bacteria would be in the grey area. If 1 bacterial species can cause a mild illness in 1 person but a very severe illness in another, should bacterial illness be allowed at all? I honestly think it should, but only some bacteria. Streptococci would be one of those allowed types of bacteria. Food borne bacteria such as salmonella would likely also be allowed since salmonellosis would most likely result in gastroenteritis. Some subspecies of salmonella can cause typhoid fever or paratyphiod fever though. These are the life-threatening types of salmonella. But like I said, most salmonella would only cause gastroenteritis. In fact lots of different bacteria can cause gastroenteritis.

Parasites are another gray area. You have 2 types of parasites, heleminths, such as tapeworms, and protozoa, such as plasmodium falciparum. Malaria is parasitic but it causes hemolytic anemia and periodic fevers. Plus, it is unlikely that mosquitoes would survive on a generation ship due to lack of stagnant water. Intestinal parasites on the other hand will most likely only cause diarrhea or sometimes, no symptoms at all.

So far we have this on the spectrum:





There is only 1 pathogen left. That is prions. These are not organisms nor are they cellular parasites(viruses are in a sense cellular parasites because they invade cells to cause an infection and can't multiply without the cells), they are simply proteins that are misfolded which cause normal proteins to become misfolded. The only way I could see getting rid of prions before infection is a lot of protease supplements on top of normal digestive enzymes to ensure the proteins are broken down. This would not be ideal because it is quite possible that these proteases would themselves cause intestinal inflammation. So this would be in the red area, absolutely not allowed, not even in 1 person.

So here is the full spectrum:





However, if I were to go through a list of every infectious illness and decide whether or not it is allowed, should I have a death rate limit? Is there a point at which pregnancy rate and more importantly birth rate, can't overcome the death rate from infection assuming an average death rate of 8 per 1000 per year from other causes?

So is there a point at which death rate from infection would cause something like this to happen to the population:





In other words exponential decay once the birth rate lowers to below the death rate?

Assuming about a fourth of the women are in the fertile window per week and a sex ratio of 1:1, this means with every pairing, there is at most a 25% pregnancy rate per week in the population. But of course, those that didn't get pregnant before would try again and so it would increase to be more than 50% of the women within a month that get pregnant, say something like 80%. Of those that get pregnant say 20% miscarry and 1% end up with a stillbirth. This would mean a 79% birth rate in pregnant women which would mean a 31.6% birth rate in the population overall. And this 31.6% would be every 2 years, except that 2% of breastfeeding women will get pregnant before their periods and the chance of getting pregnant increases with every passing period until after 2 years, when breastfeeding stops, it gets back to the 80% rate. Sort of like a slow but exponential growth.

Main reason for allowing illness? Immune systems in their prime and prevention of these:

Autoimmune disease(without illness, it is more likely the immune system will see something harmless as foreign)
Allergies(same thing, just not against human tissue)
Weak immune system(this would be the worst, this could mean major die off from minor illness)


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## pmmg (Apr 16, 2018)

You do understand that this is for a work of fiction? And that you get to make up the details as you go? And if you don't want all the characters to end up dead because bacteria got to them, then you don't have to write it that way?

This all seems well written out, but I am not sure that any of it necessarily equates to some of the things concluded. For example, why would there be exponential decay once the birth rate gets lower than the death rate? Why can that not just trickle on. I am also not sure why we must assume there will be a die off at all. While bacteria and virus's may be present, a great many of them can be far less than fatal.

I suppose the big factor I don't see included is just that of the reaction of people in these circumstances. What would a person do if a die off started to happen? These are people with a bit of Knowledge I would assume. If people start to get sick, I suspect people would become more cognizant of it and react accordingly. Or, in other words, the people would not just let themselves die off if they could help it. So, I don't think you will end up with a graph that just swoops down. I think you will find, things happen and people adjust. I also suspect such a graph would not end up having such a steep slope.

Very educational though.


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## caters (Apr 18, 2018)

See, what I think would happen is that because people sleep so close to each other on the generation ship and have sex on a regular basis(Yes, even those women on their period have sex. I mean it is possible to ovulate so close to your period or even on your period and have the egg be fertilized and implant after the period is over), illness would be transmitted rapidly and that especially among children, they would easily transmit a stomach bug to someone else or reinfect themselves with the stomach bug. Even if they had masks on, some viruses could still get through the mask and be transmitted. And well, it is inevitable that some people are going to get bleeding injuries or that some women will get vaginal irritation and with regular sex for the purpose of pregnancy, something is eventually going to get sexually transmitted, be it yeast or something else.

And I am not saying that all illnesses are fatal. Like I said, the cold virus would be no big deal. And most gastroenteritis would again, not be fatal. Pretty much any fungal infection would not be fatal unless the person was immunocompromised or already had a different infection, then there is a chance it could be fatal. Also, like I said, prions would eventually be fatal after some time because they are misfolded proteins and lots of protease to prevent the prions from infecting someone could lead to digestive issues such as malabsorption. This would then lead to deficiencies which can cause everything from weak bones(such as those of people with rickets) to excessive bleeding(such as in vitamin C deficiency) to small red blood cells(lack of iron) and more.

As for why there is the exponential decay and why there would be a die-off? Well no illness will make it easier to conceive or easier to have multiples. With illness, at least some, fertility rate would drop. With this fertility rate drop, less people will conceive. With other illnesses such as viral pneumonia, it would simply be the death rate lowering the population that will cause fewer to conceive. Fertility drop + death = way lower pregnancy rate which leads to a lower birth rate which just worsens the situation.

This is why I think there is no trickling off and instead exponential decay once birth rate gets higher than death rate.


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## pmmg (Apr 18, 2018)

Ah Caters, I feel like I am being trolled again. What is the purpose of all of this? What does any of this matter? Is this really the kind of stuff that your story is stuck on? So what if there would be a die off or not, or they have sex or not, or whatever...its a story. Are you really trying to account for the mutation of prions and staff infections and rhino virus's? Why?

I think, in spite of all the biology, and science and whatever you are putting into this, life finds a way and the people make it. If you want to write a story where they don't, hey, I think you got it covered. Bacteria gets them. And there you go.

Personally, I doubt there will be as much sex as you are alluding to, and I doubt the people (if they are people, cause I am not even sure) will continue to engage in behavior that leads to their demise. Id like to say this is a neat intellectual exercise, but some of the stuff you seem a bit fixated on is just...why? My suspicion, they grow to the size of their environment and kind of plateau there. I think you are suffering from too much science and not enough spirit. Where is the spirit of these people?

You know what solves your sex problem, marriage. Have them get married and the sex will stop 



caters said:


> However, if I were to go through a list of every infectious illness and decide whether or not it is allowed, should I have a death rate limit? Is there a point at which pregnancy rate and more importantly birth rate, can't overcome the death rate from infection assuming an average death rate of 8 per 1000 per year from other causes?



The answer is, its however you want to write it.

Later Dude, or Dudette.


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