Fig. 2

Parasite tissue stages of Leucocytozoon, Haemoproteus and Plasmodium in naturally infected wild birds, identified by CISH and in HE-stained sections. a–f Multiple meronts of Leucocytozoon sp. in the kidneys of a hawfinch coinfected with Haemoproteus and Leucytozoon. CISH using a Leucocytozoon-specific probe showed strong labelling of meronts in infected kidney cells, confirming their generic identity (inserts a–d). The meronts (black arrows) were mostly located in renal tubular cells and contained developing merozoites of varying maturity. Occasionally, a deformed or enlarged host cell nucleus, characteristic for Leucocytozoon-infected host cells, was visible (c, f, white arrows). g–i Leucocytozoon tissue stages in the kidneys of a hawfinch infected with the lineage HAWF7. The parasite stages were located in single infected host cells (g, black arrow), sometimes featuring an enlarged host cell nucleus (white arrow), or in multiple adjacent host cells (presumably renal tubule cells) (h), or in the intertubular space (i). j–l Leucocytozoon meronts in the proventriculus of an Eurasian bittern infected with Leucocytozoon sp. BOTSTEL01. m A Haemoproteus megalomeront in the pectoral muscle of a common chaffinch infected with Haemoproteus sp. CCF23, labelled by the Haemoproteus-specific probe (insert). The megalomeront contained numerous developing merozoites (black arrow), enclosed by an indistinct eosinophilic wall (white arrowhead). n A megalomeront detected in the muscular layer of the gizzard in a bullfinch infected with Haemoproteus sp. EMSPO03. The megalomeront was bounded by a thick eosinophilic wall (white arrowhead) and contained irregularly shaped, strongly basophilic cytomeres with developing merozoites (black arrow). o Plasmodium blood stages detected by CISH in the lung of a great tit co-infected with P. relictum SGS1 and P. elongatum GRW06. Scale bars: 50 μm