There is a wide variety of enteropathogens that causes diarrhea,including bacteria,viruses, and parasites. The main mechanism of transmission for diarrheal pathogens is fecal-oral,with food and water being the vehicles for most episodes. The relative importance and epidemiologic characteristics of diarrheal pathogens vary by geographic location. The main viral agents are Rotavirus, Enteric Adenovirus and Norwalk agent. Because these organisms involve predominantly the colon, the diarrhea is small in volume.
Fecal leucocytes are present in infectious with invasive organisms.
The major parasitic enteropathogens are Giardia lamblia , Cryptosporidium parvum and Entamoeba histiolytica. In Brazil, Ascaris lumbricoides and Strongyloides stercoralis have a high prevalence. Examination of more than one stool specimen may be necessary to stablish a diagnosis. In developed countries , as United States of America , the examination of patient s stool specimen must be required if there is a history of recent travel to an endemic area , negative stools cultures for other enteropathogens , persistent diarrhea, or if the patient is immunocompromised. 3.Mehta DI, Lebenthal E. New developments in acute diarrhea.