But once it has succeeded in wiping out its entire host population then it has nowhere to go. The ease of transmission only affects how quickly it loses all its hosts as does the length of dormancy (latency). To be successful any host-dependent organism needs to keep enough hosts alive to enable it to pass into them - so that sometimes means a dense enough remaining population for the distance to be transmitted not to be too far (except diseases which are transmitted by mobile vectors, such as insects and birds, and the fact that human travel means distance is now less important).

 

As you clarified this for me in a later post, I can inform you that it is very likely that the virus was species specific (in that it affected chickens but not pigs - just like 'foot-and-mouth disease' affects cattle but very rarely humans). Some diseases however can pass from species to species, for example birds > pigs > humans AND MUTATE (change form) as they do so. This means a virus, as it is usually viruses, which is pretty harmless to humans can pass through other species and come out as a very dangerous one, capable of killing millions of humans (as in the 1918 flu pandemic) - and this is how the next flu pandemic (or other decimating human disease) may well occur.

 

My immediate thought is that a neighbour hates your success and poisoned the lot.
But looking at other peoples experiences/stories it would seem more likely there is a virus going around every few years...

Then my next thought would be birdflu, which in some cases can transmit to pigs and sheep and stuff. Rarely to humans, but it does happen occasionally.

To indicate how serious this can be - In the Netherlands, where I'm from, they clear out (read: gas and burn) all farm animals in a 5 to 40km radius once birdflu/fout-mouth disease (or something similar) has been found at a farm. Around that area there is usually a quarantine area, just in case.

 

There is also the well known Plague Inc. game for Android and PC which have a similar target.