CDC: Flu widespread in 15 states ATLANTA, March 16 (UPI) -- U.S. influenza activity remained elevated in some areas but the rate of influenza-like illness remains relatively low nationally, federal health officials said. The Centers for Disease Control and Prevention in Atlanta said of the 4,742 specimens tested by U.S. World Health Organization and National Respiratory and Enteric Virus Surveillance System collaborating laboratories, 23.2 percent were positive for influenza for the week ending March 10. The proportion of deaths attributed to pneumonia and influenza was below the epidemic threshold and no influenza-associated pediatric deaths were reported. The proportion of outpatient visits for influenza-like illness was 2.2 percent, which is below the national baseline of 2.4 percent. However, 15 states reported widespread geographic activity -- California, Nevada, Colorado, Missouri, Oklahoma, Minnesota, Iowa, Nebraska, Illinois, Michigan, Kentucky, New York, Pennsylvania, Maryland and Virginia. Twenty-two states reported regional influenza activity; three states reported local activity; the District of Columbia, Puerto Rico, and 10 states reported sporadic activity, and Guam and the U.S. Virgin Islands reported no influenza activity, the CDC said. The timing of influenza activity and the predominant virus can vary by region and even between states within the same region. Nationally, seasonal influenza A (H3) viruses have predominated since the start of the 2011-2012 season and remain overwhelmingly predominant in Region 5 -- Illinois, Indiana, Michigan, Minnesota, Ohio and Wisconsin -- and Region 7, Iowa, Kansas, Missouri and Nebraska. Although seasonal influenza A (H3) viruses remain predominant in the majority of regions, the overall proportion of 2009 H1N1 viruses is increasing nationally and in several regions, the CDC added.