Simplify the following text for a Grade 6 native English-speaking person.
Original: West Nile Virus ( WNV ) is a microscopic organism that has caused outbreaks of deadly disease in horses , birds , and humans . The virus is named for a province in Uganda where it was first discovered in 1937 .
Simplified: West Nile virus ( WNV ) is a virus of the family Flaviviridae .