if you test on a regular bases then you wouldnt end up with birds that are very ill in the first place , if i came across an ill bird , first id isolate have a testing kit already at home or be prepared to travel the 70 miles if your birds are worth it , ill birds or birds falling ill have weak immune systems and are a gate way to illness in any loft , i would promtly remove these birds no mater of cost or racing ability