Some questions about death and infection rates

[tamtrible]

time: nowish; place: in the general vicinity of Washington and Oregon, at least initially

Comments

[marycatelli]

Regardless of the means of transmission, there's going to be a LOT of variation. Does exposure equal infection, or is it hard to get even then?

[tamtrible]

Full-on exposure (eg an actual bite, or a serious french kiss, or unprotected sex) generally means infection, but cursory exposure generally doesn't. Though I'm not 100% certain how plausible that is biologically. Basically, what I figure is there are a *lot* of spores being given out, but they're relatively fragile until they establish. So, if you get enough of a dose that you can't fight off all the spores before they can worm their way into somewhere "safe", you'll be infected and stay infected.

[corvideye]

It seems plausible given that HIV and ebola spread in a very similar way. Perhaps you could look at HIV infection rates from the early 80s (before the transmission rate was fully understood) and correlate that with more standard death rates.

[tamtrible]

I think it spreads a *little* more easily than HIV (afaik you can't get HIV through oral sex or kissing), but it'll at least give me a good jumping-off point, thank you.

[nineveh_uk]

I'm getting numbers suggesting that around 8 people out of 1000 die every year, so I'm guessing it'd be rare to go more than about a month, maybe 2, without someone dying out of 1000 infected people.

That's going to depend a lot on who your infected people are. Cross-section of the population containing elderly people, infants, people with life-limiting illness? Or a bunch of high-schoolers. I have no idea if your figures are true, but IF they are for the whole population, and IF your pool of zombie-infected people is spread across the whole population, then your rate of people dying could be OK. But if the people who are getting infected by the zombie disease aren't the whole population, but a particular group, then your rates will be very different. In the UK the annual risk of death for a child aged 5 - 14 is about 1 in 10,000. If on the other hand your infected people are all elderly, you'll get more people dying.

[marycatelli]

Note there are diseases, such as the Spanish Influenza, where the death tools are reversed: high among adults, low among elderly and infants.

That appears to be the result of immune system reactions, not the disease per se, but it's another possibility.

[tamtrible]

Well, it will be somewhat disproportionately, well, people who share fluids with each other. So, anyone who has lots of sex, IV drug users, people who kiss each other on the mouth... so probably *somewhat* fewer infants, though relatively more (active) older people than you might expect.

[adafrog]

Another thing you need to know is how many people innoculated get the illness. Eg. 10 people can be infected with strep throat, but not all will get the illness-depends on amount of innoculation each person got, their own immune system, etc.

[marycatelli]

Plus the peril of asymptotic carriers.

[moon_custafer]

From the OP's description, it sounds as though all the infected are asymptomatic until something else kills them.

[tamtrible]

Exactly. The zombie fungus basically bides its time until you're dead. You have *slight* symptoms (you'll find yourself craving protein a little bit more, as the fungus is stealing some of yours), but other than that you could be infected for years without realizing it unless you were actually tested.

[orthent]

Perhaps this paper can help you to develop a model for infection?

http://terpconnect.umd.edu/~jzsimon/hlsc374/ref/Blais%2BWitkowski-handout-2013.pdf

It purports to be an improvement on the original Munz et al paper "When Zombies Attack: Mathematical Modeling of an Outbreak of Zombie Infection."

Is your fungus going to behave like a water mold that depends on swimming spores to reach a new host, instead of the spores being released explosively into the air like cordyceps?

[tamtrible]

I shall have to look into that water mold thing. That might explain the lack of, eg, airborne infections.

[orthent]

A chytrid fungus (like the one implicated in frog die-offs worldwide) would also produce swimming spores, so that's another possibility.

[tamtrible]

Promising, thanks for the additional angle of attack.