The ASO Test Cassette (Whole Blood/Serum/Plasma) is a test based fluorescence immunoassay for the quantitative detection of Anti-streptolysin O (ASO) in human whole blood, serum or plasma specimen. The anti-streptolysin O titer (ASO) is mainly used to determine whether a previous group A streptococcal infection caused a post-streptococcal disease such as scarlet fever, rheumatic fever, or kidney disease called glomerulonephritis.