On PBS last night (with the manipulative Bill Moyers) they presented a study on the avian flu as it is occurring right now.

One viralogist said that the expected sequence of events leading to a pandemic would be:

8 or 10 people identified as infected, most of them from the same cause, i.e. in common eating sick fowl. (This has happened.)

The next step would be an outbreak here and there of infected people ranging from people of the same village as the first patients to an occasional caregiving person such as a nurse or a doctor, indicating human to human adaptation. (This has happened.)

Next would come, say, 800 people identified as victims. He said that at this point it would still be containable by means ranging from closing schools and offices to isolating towns and villages. Vaccines and medications such as Tamiflu would be instituted on a massive scale. (This has not (yet) happened.)

The next step would be reports of thousands of people. No longer containable.

Within three months it would be all over the world, carried by travellers and infected non-symptomatic persons.

There are a few people who test as being infected but who remain non-symptomatic. He said that that he considers those as being perhaps more dangerous, because when an infected person dies, the virus dies with its host. In a non-symptomatic person the virus is still there and available for mutation.