Geographic and host distribution of haemosporidian parasite lineages from birds of the family Turdidae

Abstract

Background Haemosporidians (Apicomplexa, Protista) are obligate heteroxenous parasites of vertebrates and blood-sucking dipteran insects. Avian haemosporidians comprise more than 250 species traditionally classified into four genera, Plasmodium, Haemoproteus, Leucocytozoon, and Fallisia. However, analyses of the mitochondrial CytB gene revealed a vast variety of lineages not yet linked to morphospecies. This study aimed to analyse and discuss the data of haemosporidian lineages isolated from birds of the family Turdidae, to visualise host and geographic distribution using DNA haplotype networks and to suggest directions for taxonomy research on parasite species. Methods Haemosporidian CytB sequence data from 350 thrushes were analysed for the present study and complemented with CytB data of avian haemosporidians gathered from Genbank and MalAvi database. Maximum Likelihood trees were calculated to identify clades featuring lineages isolated from Turdidae species. For each clade, DNA haplotype networks were calculated and provided with information on host and geographic distribution. Results In species of the Turdidae, this study identified 82 Plasmodium, 37 Haemoproteus, and 119 Leucocytozoon lineages, 68, 28, and 112 of which are mainly found in this host group. Most of these lineages cluster in the clades, which are shown as DNA haplotype networks. The lineages of the Leucocytozoon clades were almost exclusively isolated from thrushes and usually were restricted to one host genus, whereas the Plasmodium and Haemoproteus networks featured multiple lineages also recovered from other passeriform and non-passeriform birds. Conclusion This study represents the first attempt to summarise information on the haemosporidian parasite lineages of a whole bird family. The analyses allowed the identification of numerous groups of related lineages, which have not been linked to morphologically defined species yet, and they revealed several cases in which CytB lineages were probably assigned to the wrong morphospecies. These taxonomic issues are addressed by comparing distributional patterns of the CytB lineages with data from the original species descriptions and further literature. The authors also discuss the availability of sequence data and emphasise that MalAvi database should be considered an extremely valuable addition to GenBank, but not a replacement.

Plasmodium matutinum Transmitted by Culex pipiens as a Cause of Avian Malaria in Captive African Penguins (Spheniscus demersus) in Italy

“…Avian malaria is a parasitic disease of birds caused by protozoa belonging to the genus Plasmodium , within the order Haemosporida ( 1 , 2 ). The genus Plasmodium is the largest genus within this order and currently consists of more than 50 species worldwide distributed both in tropical and temperate areas ( 1 – 7 ).…”

“…Avian malaria identification at species level has traditionally relied on morphological analyses of parasites seen on blood smears. More recently, molecular characterization has led to the description of multiple parasites lineages, and these lineages have been gradually assigned to their respective morphospecies ( 2 , 6 , 8 , 9 ). DNA-barcoding of multicellular eukaryotes often target sections of mitochondrial genes, specifically of the cytochrome c oxidase subunit I and of the cytochrome b (cyt b ).…”

“…DNA-barcoding of multicellular eukaryotes often target sections of mitochondrial genes, specifically of the cytochrome c oxidase subunit I and of the cytochrome b (cyt b ). In particular, the cyt b has became the reference gene for DNA-barcoding approaches of avian haemosporidians ( 2 ). Plasmodium spp.…”

“…In particular, the cosmopolitan P. relictum has been recorded in over 400 bird species, belonging to 70 families ( 3 , 7 , 10 ). In Europe, several Plasmodium species have been so far detected in both birds and mosquitoes, such as P. relictum, P. vaughani ( 2 , 11 – 15 ), P. elongatum and P. matutinum ( 2 , 4 , 5 , 16 , 17 ). However, as in some studies dealing with avian malaria specific identification of the parasite was not performed, neither morphologically nor through molecular or combined approaches, this list of species should be considered presumably incomplete ( 18 ).…”

“…However, as in some studies dealing with avian malaria specific identification of the parasite was not performed, neither morphologically nor through molecular or combined approaches, this list of species should be considered presumably incomplete ( 18 ). Indeed, the issue of relating molecular genetic data to classical taxonomy, primarily based on the morphology of blood stages, and the vector and host susceptibility of the parasites, has already been raised ( 2 ).…”