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I can see the chain of spreading disease: Humans usually get rabies from domestic animals, those usually get it from wild animals, wild animals in their turn get from the other wild animals and here I'm stuck. Well, so where do wild animals get it from initially?

I know that rabies is a virus and it needs warm-blooded animals to live out. Also according to Wikipedia once an animal is effected it lasts, let's say, no longer than for 2 weeks.

In other words, does it mean that there is a constant population of rabid animals that exists in order to pass this virus from one animal to another every 2 week on the average?

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Hi! If you have think the post by Chris sufficiently answered your question, please accept it by clicking the checkmark.(This site is in beta so improving statistics is vital!) – biogirl Mar 11 '14 at 16:44

Such viruses have a natural host, which might get sick, but is usually not killed by the virus. From there, the virus can get zoonotic (jump over species barriers) and infect other animals when it comes to contact. For Rabies the reservoir hosts are different, for the US these are bats, skunks and racoons. For more details, have a look on this PDF.

Another example for this is the SARS virus (a corona virus) which most likely lives in bats naturally and has jumped from there onto birds and from there infected humans.

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Thank you very much for this PDF. The only section I found which explains virus origin is "Mechanisms of Attachment". Still I'm not sure I get it, could you rephrase it in layman's terms? – dVaffection Mar 11 '14 at 17:56
@dVaffection For example, ticks can carry lime disease, they're not affected by it but can still pass it on to you. Similarly mosquitoes and malaria. The latter is explained nicely in wikipedia. You can have a similar situation with viruses, that's what Chris means by "natural host". – terdon Mar 11 '14 at 18:16
@terdon Also "Natural hosts" are referred as reservoirs - I totally get it. But somehow those animals get this virus in the first place and this virus stems from somewhere! – dVaffection Mar 11 '14 at 18:28
@dVaffection that one is the age old question of the chicken and the egg, not really within the scope of this site :) Anyway, many viruses can survive outside a host (for a given value of "survive") so some can be airborne and picked up by the host that way. – terdon Mar 11 '14 at 19:24
Or host and reservoir come in contact somehow and transmit the virus. It is only present for some time in the intermediate host (and will either kill him or simply leave him) before the virus gets either transmitted to another (probably better) host or the spreading stops here. – Chris Mar 11 '14 at 19:42

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