Sickle Cell Anemia is caused the same way cystic fibrosis is caused...by passing on defective genes from two carriers. As with other Autosomal Recessive Diseases, there is no other way to get this disease. It's not something that can be “caught”. In fact, just like the rest of this spectrum, you couldn't get infected with Sickle Cell Anemia even if you wanted to...not that you'd want to.
But speaking of which, some theorists have presented a reason that, at least as far as adaptation and evolution are concerned, Sickle Cell was the body's response to a bigger problem: Malaria. I don't believe in evolution in the grand scheme of things. I don't see how it could explain things better to me than having faith that God created everything, but the fact is, our bodies have changed somewhat over time. We have different skin tones, different heights and builds, etc, depending on where we are from. According to one theory, Sickle Cell Anemia developed as a result of the ancient spread of Malaria. If you look at the Wikipedia article on the disease, you can see how this hypothesis makes sense, at least on the surface. While malaria is not a threat to humans in North America, we have the traits present with us because of various forms of immigration.
There are theories on the other autosomal recessive diseases as well. If this truly does point to a form of evolution, and this is only the form referred to as adaptation, then it would show that there is no silver bullet for our body physiology. The give and take of Sickle Cell is rough, exchanging whatever benefit regarding malaria for a life of trouble with the disease of Sickle Cell. There's no arguing it though, because it's already here, and our efforts would be better served by focusing on better treatments and a cure.
Like many of the autosomal diseases, there is no cure yet for Sickle Cell Anemia. However, there are many treatments available to those who have the disease. These are promising and aid in giving long life to those who suffer from the disease.
If you want to help out with Sickle Cell, please visit the American Sickle Cell Anemia Association website and see where you can help today!
The greatest thing about this website, aside from the fact that this organization helps with those suffering from Sickle Cell Anemia, is it's comprehensive list of what most states test for in newborn screenings. This was so awesome to find. Go HERE to see the list.