Comparative copro-diagnosis of Echinococcus multilocularis in experimentally infected foxes

Faecal samples from 15 foxes experimentally infected with Echinococcus multilocularis were examined until 90 days post-infection (dpi) by microscopical identification of eggs isolated by flotation/sieving, by coproantigen-enzyme-linked immunosorbent assay (cELISA), by polymerase chain reaction (PCR) on DNA, respectively, isolated directly from the faecal samples (copro-DNA PCR) and from the eggs obtained by the flotation/sieving procedure (egg-DNA PCR). Based on egg counts, three periods of the infection were defined: pre-patent (2-29 dpi), high patent (30-70 dpi) and low patent periods (71-90 dpi). Whereas all methods were highly sensitive with samples from the high patent period, cELISA was the most sensitive to detect pre-patent infections (63%). Samples from the low patent infections were positive in 77% by microscopy and in 80% by egg-DNA PCR, being significantly more sensitive than cELISA and copro-DNA PCR. The isolation of eggs from the faecal material proved to be more sensitive by the flotation/sieving procedure as compared to the classical concentration McMaster technique.