Metametrix Labs enteric panel ( uses DNA to id parasites and other microorganisms)
Diagnostecs Lab stool and saliva exams. ( uses serology and microscopic exams)
When a person had obvious symptoms of Giardia I would usually see the protozoa on the microscopic stool exams and it was one of the most common of the parasites I saw.
Saliva tests for parasites is offered by a lab in Switzerland and by a few Hulda Clark practitioners.
A local ND uses muscle testing for parasites - she says it is about 80% accurate.