Boone and Marion counties have joined the list of spots where West Nile virus has been detected in Arkansas this year. The state Health Department says birds tested positive in those two counties. So far this year, 23 human cases of the disease have been reported. Jefferson County has had seven confirmed human cases, Pulaski County has three, Miller and Arkansas counties have two each and Benton, Cleburne, Columbia, Drew, Johnson, Pope, Sevier and Union counties each have one. The mosquito-borne virus has been detected in humans, horses, birds, or mosquito pools in 50 counties. Most people who contract the disease have mild or no symptoms. In rare cases, the illness can cause fatal brain swelling. Last year, the department reported five deaths in the state among people who contracted the virus. ------ The counties where West Nile has been detected are: Arkansas, Ashley, Benton, Boone, Bradley, Chicot, Clark, Clay, Cleburne, Cleveland, Columbia, Craighead, Crawford, Conway, Dallas, Desha, Drew, Faulkner, Franklin, Greene, Hempstead, Hot Spring, Independence, Jefferson, Johnson, Lafayette, Lawrence, Lee, Little River, Logan, Lonoke, Marion, Miller, Mississippi, Monroe, Newton, Phillips, Poinsett, Pope, Pulaski, Randolph, Saline, Sebastian, Sevier, Scott, Stone, Union, Van Buren, Washington and Woodruff.