Based on the World Health Organization (WHO), the most common flavivirus infection in the United States and most part of North America is the West Nile Virus. Other affected areas are Africa, Europe, the Middle East and West Asia.
As described by WHO it is a fatal neurological disease to humans caused by bites of infected mosquitoes, contact with infected animals, breast feeding of an infected human, and blood transfusions. The source of this virus mostly comes from birds.