Vector-Borne Blood Parasites of the Great-Tailed Grackle (Quiscalus mexicanus) in East-Central Texas, USA

Great-tailed grackles (Quiscalus mexicanus) have dramatically expanded into North America over the past century. However, little is known about the blood that parasites they support. Here, for the first time, we document an assemblage of trypanosome, haemosporida, and filarial nematodes co-circulating in invasive great-tailed grackles. Between February and July, 2015, 61 individuals were captured in an urban environment of College Station, Texas. Field microscopy and molecular diagnostics indicate that 52% (24/46) were visually infected with filarioid nematodes, 24% (11/46) with avian trypanosomes, and 73% (n = 44/60) with haemosporida parasites, such as Haemoproteus (Parahaemoproteus) and Plasmodium cathemerium. Overall, 87% of great-tailed grackles were infected with blood parasites. Although 50% of individuals hosted parasites from multiple phylum, no patterns of parasite assembly were observed. Results indicate that great-tailed grackles can support a relatively high level of blood parasitism. However, the consequences for avian health remain to be determined.

Morphological and molecular characterization of Plasmodium cathemerium (lineage PADOM02) from the sparrow Passer domesticus with complete sporogony in Culex pipiens complex

Avian malaria is a mosquito-borne disease caused by Plasmodium spp. protozoa. Although these parasites have been extensively studied in North America and Eurasia, knowledge on the diversity of Plasmodium, its vectors and avian hosts in Africa is scarce. In this study, we report on natural malarial infections in free-ranging sparrows (Passer domesticus) sampled at Giza Governorate, Egypt. Parasites were morphologically characterized as Plasmodium cathemerium based on the examination of thin blood smears from the avian host. Sequencing a fragment of the mitochondrial cytochrome b gene showed that the parasite corresponded to lineage PADOM02. Phylogenetic analysis showed that this parasite is closely related to the lineages SERAU01 and PADOM09, both of which are attributed to P. cathemerium. Experimental infection of Culex pipiens complex was successful, with ookinetes first detected at 1-day post infection (dpi), oocysts at 4 dpi and sporozoites at 6 dpi. The massive infection of the salivary glands by sporozoites corroborates that Cx. pipiens complex is a competent vector of PADOM02. Our findings confirm that Plasmodium lineage PADOM02 infects sparrows in urban areas along the Nile River, Egypt, and corroborate that Cx. pipiens complex is a highly competent vector for these parasites. Furthermore, our results demonstrate that this lineage corresponds to the morphospecies P. cathemerium and not P. relictum as previously believed.