Stool examination via light microscopy of stained smears or wet mounts
Stool culture 
ELISA targeted at serum antibodies to<unk>  
PCR 
Fecal leukocytes are usually absent
Blastocystis species
Viral 
Cryptosporidium
Bacterial
Cyclospora
Campylobacter
Eikenella
Shigella