I think it's great that everybody here is trying to help, but try not to misguide him with your own diagnoses. Whatever it may "sound like", we have no idea what he has. This certainly does not sound like typical West Nile Fever, which in most people is a very mild, non-specific flu-like illness without shaking chills, severe sore throat, and significant weight loss. More severe forms of WNV have more neurological symptoms, which he hasn't really described.
Here is some info for those who are interested.
Even if it does turn out to be WNV, no need to freak him out like this. He just needs to get to a doctor.
And please don't mention malaria unless the guy has been out of the country to a malaria-endemic area.