Microscopic and molecular analysis of protozoan parasites (particularly amoebas) in wool sheep coprologies in the Canary Islands

Abstract

A significant number of parasitic protozoa can be found in the gastrointestinal tract of large and small ruminants. Some of them, such as Cryptospordidium, Giardia and certain species of the genus Eimeria have been described as the cause of clinical disease leading different clinical signs, including diarrhea, and can then produce important production losses on farms. In contrast, other protozoa are considered nonpathogenic, of low pathogenicity or even commensals of the gastrointestinal microbiota of ruminants. This second group of protozoa has been poorly studied though, despite they include genera described as potentially pathogenic in humans and could therefore have zoonotic implications. In the present study we have addressed a preliminary epidemiological study on the last group of protozoa. Special attention was paid to the genus Entamoeba, whose cysts are commonly observed in fecal samples of small ruminants at our laboratory in routine diagnosis. For this purpose, a total of 80 adult wool sheep belonging to 10 farms located in different areas of the Gran Canaria island (Spain) were sampled. Fecal samples were processed and observed by microscopy. Nine of the ten farms tested were positive for Entamoeba spp, while other protozoa, particularly Chilomastix-like cysts, were found in 6 out of the 10 farms. Positive samples to Entamoeba and Chilomastix-like cysts were pooled and further analyzed by molecular methods, for what PCR was standardized based on previously described studies. Providing that sequencing confirms the results, positive PCR reactions were obtained for both protozoan in some farms. However, the data achieved by PCR poorly correlated to microscopic observations. Whether this may be because the cysts observed are different isotypes or species from the one the primers amplified, or due to dilution of the cysts when making the pools, remains unclear, and further studies are necessary. From the present study we can conclude that a high percentage of wool sheep of the island are infected by Entamoeba spp, but the clinical implications of this finding required additional research. Interestingly, although with a prevalence rather low, the presence of Chilomastix in sheep would be of high importance due to the zoonotical potential of this protozoa