Abnormal helminth egg development, strange morphology, and the identification of intestinal helminth infections

Abstract

Occasionally, abnormal forms of parasitic helminth eggs are detected during routine diagnostics. This finding can prove problematic in diagnosis because morphologic analy­sis based on tightly defined measurements is the primary method used to identify the infecting species and molecular confirmation of species is not always feasible. We describe instances of malformed nematode eggs (primarily from members of the superfamily Ascaridoidea) from human clin­ical practice and experimental trials on animals. On the ba­sis of our observations and historical literature, we propose that unusual development and morphology of nematode and trematode eggs are associated with early infection. Fur­ther observational studies and experimentation are needed to identify additional factors that might cause abnormalities in egg morphology and production. Abnormal egg morphol­ogy can be observed early in the course of infection and can confound accurate diagnosis of intestinal helminthiases.