Nested PCR amplification of DNA from eggs added to 1,500 μl of diluted fox feces free of E. multilocularis. A total of 10 μl of PCR products was separated on a 1.5% agarose gel and stained with ethidium bromide. Lane A, positive control; lane B, one egg; lanes C, D, E, F, G, H, and I, egg suspensions; lane C, 200 eggs; lane D, 100 eggs; lane E, 50 eggs; lane F, 20 eggs; lane G, 10 eggs; lane H, 2 eggs; lane I, 1 egg; lane J, negative control; lane M, size marker.