Testing for eggs and parasites in stool is often ordered at the same time as a stool culture to find, especially in travellers, the cause of diarrhea that has lasted for several days and that contains blood and mucus. A wide variety of single-cell parasites, worms, etc. can infect travellers, and many are present even here in Canada.
Among the most common parasitoses are those caused by Entamoeba histolytica/dispar, Giardia lamblia, Cryptosporidium sp. and Cyclospora cayetanensis. These four types of parasitosis are considered reportable diseases in Quebec. Other parasites such as Dientamoeba fragilis, Balantidium coli, Endolimax nana, Blastocystis hominis or worms (ascaris, strongyloides, etc.) can also be detected. The severity of the parasitosis and its treatment will vary depending on the parasite identified.
Negative results usually mean the diarrhea is not of parasitic origin. However, the number of parasites or eggs may have been insufficient for detection, despite testing on three different fecal specimens.