West Nile virus

Fifteen years ago an unwelcome viral visitor entered the U.S., and we've been paying for it ever since.

The U.S recorded its first case of West Nile virus back in 1999. Since then, the disease has spread across the lower 48 states and cost the country around $800 million, scientists reported this week in the American Journal of Tropical Medicine and Hygiene.

Louisiana's worst year for West Nile virus in a decade continues into the fall season. On Friday the state Department of Health and Hospitals reported 12 new West Nile virus cases, and two more West Nile-related deaths.