Does everyone who gets infected become severely ill?
No. Experts estimate that less than 1% of those infected with West Nile virus will develop severe illness, and only 3-15% of severely ill people will die as a result. In people who develop severe illness, West Nile virus multiplies in that individual’s blood system following transmission by an infected mosquito; the virus then travels to the brain. It interferes with normal brain functioning and causes inflammation of brain tissue (called encephalitis).
