Persistent low avian malaria in a tropical species despite high community prevalence

Malarial and other haemosporidian parasites are widespread; however, their temporal dynamics are ill-understood. Longitudinal sampling of a threatened riparian bird revealed a consistently very low prevalence over 13 years (∼5%) despite infections persisting and prevalence increasing with age. In contrast, three key species within this tropical community were highly infected (∼20–75% prevalence) and these differences were stable. Although we found novel lineages and phylogenetic structure at the local level, there was little geographic structuring within Australasia. This study suggests that malarial parasite susceptibility is determined by host factors and that species can maintain low levels despite high community prevalence.
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Highlights • Malarial parasite prevalence varied between species (∼5–75%). • Persistent and low prevalence over 12y in a riparian bird. • Oldest age category had highest parasite prevalence. • Parasites showed genetic structure at the local level but not within Australasia. • Tropical species can maintain low malarial parasite levels despite high exposure.