Limits on testing for bird flu in humans could pose difficulty for containing spread The GuardianCDC releases blood test results on Missouri bird flu patient as cases spread NBC NewsAs Bird Flu Spreads, Additional Human Infection Is Reported in Missouri The New York TimesSerologic tests rule out avian flu in Missouri health workers; CDC confirms 2 Washington infections University of Minnesota Twin CitiesBlood tests confirm a second person in Missouri caught bird flu without exposure to infected animal, but questions remain CNN