Haemosporidian parasites (Apicomplexa, Haemosporida) of breeding common starling Sturnus vulgaris in Latvia

Migratory behaviour in seasonal environments affects host–pathogen relationships, especially for vector-transmitted blood parasites of the order Haemosporida. The common starling Sturnus vulgaris is a short-distance migrant where the north-eastern European breeding population spend the non-breeding season in temperate mild western Europe. Despite the high abundance and known susceptibility as a host, blood parasitism in wild starlings has rarely been studied with molecular methods. Here, we monitored haemosporidian parasitism in a Latvian starling population over four breeding seasons. We found a total annual parasite prevalence of 2.7–15.7% caused by four Haemoproteus, three Plasmodium, and one Leucocytozoon cytochrome-b (cyt-b) genetic lineages. Herein, seven of these lineages have been recorded for the first time in the common starling as host. Lineage-specific parasitemia was generally low (Haemoproteus range: 0.008–1.028%, Plasmodium range: 0.002–0.005%, Leucocytozoon range: 0.003–0.004%) indicating chronic infection stages in all parasitised hosts during the breeding season. Additionally, the proportion of leukocytes in peripheral blood was enhanced in infected compared to non-infected hosts indicating activated immune defence during the chronic infection stage. Finally, 11% (3 out of 27) of individuals had cleared the infection from peripheral blood after one year. Causes for the variability in infection prevalence in common starlings across years, as well as the transmission period during the host annual cycle, are still open for future studies.
Keywords: avian malaria, chronic infection, Haemoproteus, Leucocytozoon, leukocytes, Plasmodium