Oct. 21, 2009 (United Press International) -- When school resumed in September U.S. children ages 10-14 experienced a sharp increase in positive H1N1 results, a diagnostic testing company found.

Quest Diagnostics, a diagnostic testing company and the only provider of two commercial H1N1 tests authorized by the U.S. Food and Drug Administration for emergency use, prepared a report based on data of 76,000 specimens tested for H1N1 flu.

The report covers H1N1 testing from May 11-Oct. 11 and shows that about half of patients that clinicians suspected of having the flu -- and therefore ordered tests on -- were found to test positive for the pandemic virus.

The report found positive rates among adults and preschool age children have gained ground on school-age kids since the beginning of October.

There was also an uptick among those age 65 and older who were thought to have greater immunity.

Texas and California have shown the high testing activity overall but Arizona and Ohio are starting to see significant testing increases, the report said.