In reply to veteye:
That, or a nice picornavirus that can be blown long distances, even across the sea, with dust storms, e.g. from Northern China to Japan....
When I was still in working virology our favourite horror scenarios were a standard human herpesvirus acquiring the oncogenes from our lab pet, a leukemia inducing monkey herpesvirus, and of course ebeasles: Deadly like Ebola, but transmissible by air and infectious like measles.
In fact, this is probably what measles looked like after the virus jumped over from cows, once dairy farming and living in cities became fashionable. There are old, Mesopotamian documents available where the governor of some town writes to his king that, Crom be praised, the disease decimating his people is "only" the smallpox!
CB