Trypanosoma culicavium sp. nov., an avian trypanosome transmitted by Culex mosquitoes.

A novel avian trypanosome, Trypanosoma culicavium sp. nov., isolated from Culex mosquitoes, is described on the basis of naturally and experimentally infected vectors and bird hosts, localization in the vector, morphological characters and molecular data. This study provides the first comprehensive description of a trypanosome species transmitted by mosquitoes, in which parasites form plugs and rosettes on the stomodeal valve. Trypanosomes occurred as long epimastigotes and short trypomastigotes in vectors and culture and as long trypomastigotes in birds. Transmission of parasites to bird hosts was achieved exclusively by ingestion of experimentally infected Culex mosquito females by canaries (Serinus canaria), but not by Japanese quails (Coturnix japonica), nor by the bite of infected vectors, nor by ingestion of parasites from laboratory cultures. Transmission experiments and the identity of isolates from collared flycatchers (Ficedula albicollis) and Culex mosquitoes suggests that the natural hosts of T. culicavium are insectivorous songbirds (Passeriformes). Phylogenetic analyses of small-subunit rRNA and glycosomal glyceraldehyde-3-phosphate dehydrogenase gene sequences demonstrated that T. culicavium sp. nov. is more related to Trypanosoma corvi than to other avian trypanosomes (e.g. Trypanosoma avium and Trypanosoma bennetti).