Did the native Americans know the cold and flu virus before the Europeans arrived?

With regard to influenza, the various strains of this virus are believed to have had a common ancestral population about 8000 years ago*, near the time when humans first domesticated birds**. They would live in close proximity with the birds allowing the virus to spread.

Influenza epidemics have been dated as far back as 412 B.C.

Since the humans who moved to the Americas did so a few thousand years earlier, it is likely that influenza was unknown prior to the arrival of the Europeans.

* http://mbe.oxfordjournals.org/cgi/content/abstract/19/4/501

** Cambridge World History of Food, Kenneth F. Kiple and Kriemhild Conee Ornelas, Volume One [Cambridge University Press:Cambridge] 2000 (p. 496-499)

Quite a bit has been written about this subject actually.

When the Europeans arrived in America, they infected the natives with just about everything they had. The Europeans on the other hands didn't get anything from the natives. The answer to this is actually fairly simple.

Population density and domesticated animals.

Europeans lived in close proximity with each other and with their domesticated animals. This meant that Europe would see cycles of disease, passing from animals to humans, quickly infecting large populations because of the high population density and then mutating again to an animal form. Europe was a disease factory and those people who survived had become quite hardy against a wide variety of diseases.

Native Americans had much fewer domesticated animals, didn't tend to live as closely with them and had much lower population densities. That meant that when a virus sprung up, it had nowhere to go and would just die out fairly quickly. Native Americans just never got the chance to get the level of habituation and immunization that the Europeans got.

When the Europeans arrived ... disease hit the Native populations like a bomb. Explorers going deep into America often reported entire villages devastated and empty, disease having outran even the boldest explorer.

So..no the Natives did not know the cold and flu before the Europeans arrived, and likely many of them died of it.

Europeans did not defeat the natives with Superior technology.
They killed off the natives with disease.

I read that when the Spanish went up the Mississippi there were 77 tribes.
When the French later went down the Mississippi there were 7 left.

Enitre tribes got sick at the same time with no one to gather food.