URGENT!! What can you tell me about the West Nile Virus? a friend of mine has it!

I just got a call tonight that a guy friend of mine is in the hospital. he's got a 104 degree temp and is having an IV inserted tonight. im really worried about him. i'm looking things up right now on the virus but not finding out much more than i already know. is this virus overly dangerous? what are the risks and affects of the virus? my guy friend is a healthy 17 year old but he's not doing so well right now.