Fig. 1

a Quantification and localization of S. molnari in different organs of common carp, over 63 days post-intraperitoneal-injection (dpi), using qPCR (based on parasite SSU rDNA sequence copies); numbers are relative to the sample with the highest value (100; a liver sample from 42 dpi). b, c Kwik–Diff-stained cell preparations. b Blood smear showing multicellular parasite stages in amongst red blood cells and a lymphocyte (L); arrowheads indicate attachment sites to erythrocytes. c Liver imprint with larger, multicellular parasite stages, one showing a refractile protruding edge (arrowheads). Cell-in-cell composition is indicated in some parasite stages in b and c. Abbreviations: P, primary cell; S, secondary cell; T, tertiary cell. Scale-bars: b, c, 20 µm