How is giardiasis diagnosed?
To diagnose giardiasis, doctors may take several stool samples and send them off to a lab. The lab tests for Giardia parasites in the stool or by doing a more sensitive test called the Enzyme-Linked ImmunoSorbentAssay (ELISA). If the illness is bad enough, a doctor may take a sample of the lining of the small intestine with an endoscope (a slender medical tool), in a procedure called endoscopy.