Parasitaemia in experimentally treated and naturally infected great reed warblers. (a) Frequency of parasitaemia of the lineage pGRW04 induced in the experimental birds during the acute phase of infection (n = 16) and (b) total frequency of parasitaemia in chronically infected wild birds (n = 61). (c) Genus-specific parasitaemia (medians ± 25/75% and the ranges) in wild birds for Plasmodium ssp. (red, n = 18) and Haemoproteus ssp. (dark grey, n = 40).