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).

This study presents data from a molecular survey of the species of the genus Culicoides from the region of Kalimok Field Station (NE Bulgaria) and haemosporidian parasites occurring in them in order to investigate the host-parasite specificity of haemosporidians to their dipteran vectors. The identification of Culicoides spp. was carried out by morphological and molecular-genetic methods. We collected and analysed 230 individuals of the genus Culicoides. Nine species were found. Eight species were identified morphologically; Culicoides obsoletus, C. riethi, C. newsteadi, C. circumscriptus, C. festivipennis, C. punctatus, C. pictipennis and C. puncticollis. The ninth species might be classified as either of C. nubeculosus or C. riethi and its identification needs additional investigations. The total prevalence of Haemoproteus in the examined biting midges was 2.17%. Three individuals of C. pictipennis were infected with the Haemoproteus lineage TURDUS2 (prevalence 16.67%), a common parasite of thrushes (Turdidae). Two individuals of C. circumscriptus contained Haemoproteus lineages (prevalence 2.78%); these were the lineage HAWF2 (previously reported from Coccothraustes coccothraustes) and a new lineage CULCIR1 not previously reported in the literature.

African great apes are susceptible to infections with several species of Plasmodium, including the predecessor of Plasmodium falciparum. Little is known about the ecology of these pathogens in gorillas. A total of 131 gorilla fecal samples were collected from Dzanga-Sangha Protected Areas to study the diversity and prevalence of Plasmodium species. The effects of sex and age as factors influencing levels of infection with Plasmodium in habituated gorilla groups were assessed. Ninety-five human blood samples from the same locality were also analysed to test for cross-transmission between humans and gorillas. According to a cytB PCR assay 32% of gorilla's fecal samples and 43·1% human individuals were infected with Plasmodium spp. All Laverania species, Plasmodium vivax, and for the first time Plasmodium ovale were identified from gorilla samples. Plasmodium praefalciparum was present only from habituated individuals and P. falciparum was detected from human samples. Although few P. vivax and P. ovale sequences were obtained from gorillas, the evidence for cross-species transmission between humans and gorillas requires more in depth analysis. No association was found between malaria infection and sex, however, younger individuals aged ≤6 years were more susceptible. Switching between two different Plasmodium spp. was observed in three individuals. Prolonged monitoring of Plasmodium infection during various seasons and recording behavioural data is necessary to draw a precise picture about the infection dynamics.

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