TULSA, Oklahoma - Walgreens' latest weekly flu index chart ranks Oklahoma number one for flu activity. 

Oklahoma is followed by Arkansas and Texas for the highest amount of flu activity as of February 2, 2015. 

Walgreens says its Weekly Flu Index ranks the areas with the highest number of flu cases. The cities with the highest number of flu cases include Oklahoma City, El Paso, Tulsa, San Antonio, Little Rock and Fort Smith.

Last week, the Oklahoma State Department of Health reported there have been 58 flu-related deaths in Oklahoma since September 2014.

The OSDH releases its weekly numbers every Thursday morning.

The drugstore chain says its list is compiled using weekly retail prescription data for antiviral medications used to treat influenza across Walgreens locations nationwide.