Identifying Avian Haemosporidians in Turkey Vultures and Black Vultures from South Carolina

Alexandra Wickson, a student at the University of Georgia, worked with Dr. Michael Yabsley and others in his lab to determine parasite prevalence in vulture populations.

Abstract: Avian haemosporidian blood parasites are widespread among many families of birds and, in some species, can cause avian malaria.  In previous studies on blood parasites of vultures, prevalence and diversity of parasites were low. However, the long-term effects of infection on the birds were unknown. Overall, Turkey Vultures (Cathartes aura) have had a higher prevalence and diversity of blood parasites (i.e., Haemoproteus, Plasmodium, and Leucocytozoon spp.) compared with Black Vultures (Coragyps atratus) with only a single Plasmodium sp. infection has been reported in one Black Vulture from Florida. Based on morphological data, Haemoproteus catharti was described from the Turkey Vulture. The primary goal of this study was to better characterize H. catharti with morphologic and molecular data and to investigate ecological or intrinsic factors associated with infection. Turkey Vultures and Black Vultures were sampled at the Savannah River Site in Aiken, SC. Blood smears were immediately prepared, fixed with methanol, and stained with modified Giemsa. Parasite prevalence and parasitemia were determined by examination of at least 20,000 erythrocytes. We also conducted nested polymerase chain reaction (PCR) targeting the cytochrome b gene. We detected a high prevalence of parasites in Turkey Vultures (43%) and a complete absence of parasites in Black Vultures. No difference in prevalence or parasitemia levels were noted between sites, sexes, or age class. Phylogenetically, this parasite was most similar to a parasite reported from wood storks (Mycteria americana) from Florida. Together, these two sequences were distinct from the genera Haemoproteus and Plasmodium, and likely represent a new genus of avian blood parasite. This study documents the first genetic characterization of malarial parasites of vultures. Further genetic work targeting multiple genes is needed to confirm the phylogenetic relationship of this parasite to other avian haemosporidians.

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