What is West Nile virus?
West Nile virus is a virus that mostly spreads to people through the bites of infected mosquitoes.
Most of the people who are infected will not show any symptoms, while about 20% will develop a fever along with other mild symptoms.
About 1 in 150 people who are infected will develop a severe illness affecting the central nervous system such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes that surround the brain and spinal cord), which can be life-threatening.