West Nile virus (WNV) is usually spread by mosquitoes that become infected when they feed on infected birds, which often carry the disease. Rarely the virus is spread through blood transfusions, organ transplants, or from mother to baby during pregnancy, delivery, or breastfeeding, but it otherwise does not spread directly between people. Risks for severe disease include being over 60 years old and having other health problems. Diagnosis is typically based on symptoms and blood tests.
West Nile virus (WNV) is usually spread by mosquitoes that become infected when they feed on infected birds which often carry the disease Rarely the virus is spread through blood transfusions organ transplants or from mother to baby during pregnancy delivery or breastfeeding but it otherwise does not spread directly between people Risks for severe disease include being over 60 years old and having other health problems Diagnosis is typically based on symptoms and blood tests