Empirical evidence supports wild birds as playing a role in the interhemispheric exchange of bacteriaand viruses; however, data supporting the redistribution of parasites among continents are limited. Inthis study, the hypothesis that migratory birds contribute to the redistribution of parasites between continentswas tested by sampling northern pintails (Anas acuta) at locations throughout the North PacificBasin in North America and East Asia for haemosporidian infections and assessing the genetic evidencefor parasite exchange. Of 878 samples collected from birds in Alaska (USA), California (USA), and Hokkaido(Japan) during August 2011–May 2012 and screened for parasitic infections using moleculartechniques, Leucocytozoon, Haemoproteus, and Plasmodium parasites were detected in 555 (63%), 44 (5%),and 52 (6%) samples, respectively. Using an occupancy modeling approach, the probability of detectingparasites via replicate genetic tests was estimated to be high (ρ > 0.95). Multi-model inference supportedvariation of Leucocytozoon parasite prevalence by northern pintail age class and geographic locationof sampling in contrast to Haemoproteus and Plasmodium parasites for which there was only support forvariation in parasite prevalence by sampling location. Thirty-one unique mitochondrial DNA haplotypeswere detected among haematozoa infecting northern pintails including seven lineages shared betweensamples from North America and Japan. The finding of identical parasite haplotypes at widely distributedgeographic locations and general lack of genetic structuring by continent in phylogenies forLeucocytozoon and Plasmodium provides evidence for intercontinental genetic exchange of haemosporidianparasites. Results suggest that migratory birds, including waterfowl, could therefore facilitate theintroduction of avian malaria and other haemosporidia to novel hosts and spatially distant regions.Published by Elsevier Ltd on behalf of Australian Society for Parasitology. This is an open access article
