300 clinical laboratories in all 50 U.S. states, Puerto Rico, Guam, and the District of Columbia report results of clinical tests for influenza either through the U.S. WHO Collaborating Laboratories System or the National Respiratory and Enteric Virus Surveillance System (NREVSS).
The results of tests conducted nationwide by clinical laboratories are summarized below.
These laboratories do not specifically test for the influenza A (H5N1) virus, but by tracking the percentage of specimens tested that are positive for influenza A viruses, virologists can monitor unusual increases in influenza activity, which may be an early sign of the spread of novel influenza A viruses, including H5N1.
