Anti-Streptolysin O Antibody (ASO) Test - This test is used for detecting recent infections caused by streptococcal bacteria. These antibodies are produced by the immune system in response to a streptococcal infection, which is known for causing strep throat and other associated conditions. The test measures the presence of ASO antibodies, which typically increase one week after infection and reach their peak between two to four weeks. ASO levels are significant in diagnosing conditions like acute rheumatic fever and acute glomerulonephritis caused by streptococcal infections.