[Comparison of individual differences in the direct microscopic examination in the diagnosis of intestinal parasites]

The aim is to emphasise the importance for intestinal parasites' diagnosis by direct microscopic examination and the discrepancies among results from different microscopists.

Stool specimens were obtained from 225 children with diarrhoea after the macroscopic examination, prepared by formalineether sedimentation methods and included in microscopically examination by three different independent investigators (parasitologist, microbiologist, research assistant). Furthermore, specimens were stained with the modified Ehrlich Ziehl Neelsen method and evaluated for Cryptosporidium and Cyclospora.

A total 161 specimens were evaluated as negative by all investigators. The number of specimens containing parasites detected by at least one investigator was 64; Cryptosporidium parvum 30, Blastocytis hominis 16, Endolimax nana 5, Giardia intestinalis 4, Dientamoeba fragilis 3, Ascaris lumbricoides 3, Entamoeba histolytica/dispar 2, Cyclospora cayetanensis 1. The concordance among investigators was observed for 21 (33%) specimens; when specimens were evaluated for the presence of leukocytes and/or parasites, concordance was detected for 58 (91%) of the 64 specimens. In particular, significant differences were observed for the species level identification.

Different results can be obtained by microscopic examination according to the experience and educational level of microscopists. Therefore, we think that these tests should be performed by persons who have sufficient education and experience, if possible, combined with at least two different methods.