An immunological test (such as ELISA or immunochromatography) detects the presence of Helicobacter pylori antigens (antigens are proteins specific to the bacterium) in a stool sample. This detection indicates an active and current infection in the stomach lining. This test is accurate and non-invasive (does not require an endoscope) and is primarily used for initial diagnosis and to confirm the success of treatment (it should be performed at least 4 weeks after the end of treatment).