West Nile virus
There is no known treatment or cure for WNV.  There are no known anti-viral medications (medicines which kill viruses) which will kill the West Nile virus.  Doctors can only provide "supportive care," which means they can only treat the symptoms of WNV.  For example, they can give fluids through a needle placed into a vein if a person is very dehydrated; help the person breathe if needed; and give medications to prevent them from getting any other infections.