How does West Nile virus actually cause severe illness and death in humans?
A. Following transmission by an infected mosquito, West Nile virus multiplies in the person’s blood system and crosses the blood-brain barrier to reach the brain. The virus interferes with normal central nervous system functioning and causes inflammation of brain tissue. Q. What proportion of people with severe illness due to West Nile virus die? A. Among those with severe illness due to West Nile virus, case-fatality rates range from 3% to 15% and are highest among the elderly. Less than 1% of those infected with West Nile virus will develop severe illness. Q. If a person contracts West Nile virus, does that person develop a natural immunity to future infection by the virus? A. It is assumed that immunity will be lifelong; however, it may wane in later years. FLASH POINTS! Talking points on: WEST NILE VIRUS West Nile virus in pets: • West Nile virus is a rare disease and is not known to spread directly from animal to human; only through mosquitoes that have fed on infected birds. • Th
