I can tell you from experience, I had West Nile in 2004; it started as a mild fever, and then progressed to flu like symptoms, from there I spiked a 107.1 fever and then came the convulsions, all within 48 hours... After the convulsions were controlled I literally thought my head was going to explode, the hospital had to keep me in a dark room at the end of the hall away from noise. I couldn't walk, talk or eat... My face and head swelled and I was a blob, I don't remember much because I was so sick and I had temporary amnesia, loss of consciousness and near coma experiences ... Not fun, Im lucky I survived because I had West Nile Meningitis, the rare one that effects the spinal cord and brain. After I recovered, which took 2 and half months I saw photos of myself, I was the living dead to put it into terms.
As for swine flu, I have yet to experience that, thank goodness, but from what I have read up about it, it is similar to the human flu with often milder symptoms.
The treatments vary because there is no true treatment for viruses as they cannot be cured, swine flu is like human flu, take care of yourself drink fluids and seclude yourself from others, even if you just think you might have it. West Nile doesnt have a treatment; it is basically a treatment of controlling the symptoms and preventing dehydration and death
Mosquitoes are the carriers of West Nile and, yes, your birds can get it. I got West Nile from ONE mosquito bite... Lucky me!