The Anti-DNase B (ADNase B) test detects antibodies to an enzyme from Group A strep bacteria, confirming past or present strep infections (like strep throat or skin infections) and helping diagnose related issues like rheumatic fever or kidney problems (glomerulonephritis). It’s a simple blood test, often used with the ASO test (Antistreptolysin O), especially useful when ASO is negative, like after skin strep infections, to check for complications.