Blood Types and Illnesses
Your blood type is important for transfusions - but knowing more about your blood can help you learn what your body might react poorly with.
If your body has blood type B in it, it recognizes that B membrane as something "ok to be in my body". That is why you can get blood type B transfusions, because your body thinks, "OK I recognize this stuff, I won't attack it."
But what happens if something BAD comes into your system that happens to look like a B membrane? Such was the case in 1665, with the London Plague. The bacteria carried in by the rats was called Yersinia pestis ... and it looked almost exactly like a B membrane to the body. The result was that the majority of victims were Type B Blood people - because their Type B bodies didn't realize that the Yersinia pestis was in fact something "bad".
It's not just A, B, AB and O that defines your blood. Blood actually has over 300 different variations, and each one is meaningful in some small way or another. The Rh factor can affect transfusion success.
One factor, known as Duffy, looks just like malaria. So people who have "Duffy blood" and who then get malaria think, "Oh, it's just more of that blood-stuff" and don't try to fight it off. In Africa, where malaria is present, most people do NOT have Duffy blood. Those who had Duffy blood died out long ago. In the US, where malaria is not a problem, most people have the Duffy blood type.
More about Blood Types
Blood Types, Inheritance and Paternity
Blood Type Distributions Around the World
Blood Types and Transfusions
Important Types of Blood
The Basics of Blood
Evolution of Blood Types
Lisa's Biology Pages