Acta tropica
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In trematodiases, shape and size of the fluke eggs shed with faeces are crucial diagnostic features because of their typically reduced intraspecific variability. In fascioliasis, the usual diagnosis during the biliary stage of infection is based on the classification of eggs found in stools, duodenal contents or bile. The aim of the present study is to validate the identification of Fasciola species based on the shape and size of eggs shed by humans, characterizing their morphometric traits using a computer image analysis system (CIAS). ⋯ Measurements of F. hepatica and F. gigantica eggs originating from humans and animals from sympatric areas overlap, and, therefore, they do not allow differential diagnosis when within this overlapping range. In this sense, the new results should aid clinicians since the application of the classic egg size range in human samples may lead to erroneous conclusions. Fasciolid egg size in human stool samples ought to be corrected in books and monographs related to medical parasitology and/or tropical medicine as well as in guides for clinicians and parasitic disease diagnosis analysts.