Molecular characterization of avian malaria parasites in three Mediterranean blue tit (Cyanistes caeruleus) populations.

We genetically analysed malaria parasites (Protozoa) in three Mediterranean blue tit (Cyanistes caeruleus) populations from central Spain. A total of 853 breeding individuals were screened for parasites of the genera Plasmodium and Haemoproteus using a very efficient polymerase chain reaction approach that amplifies a partial segment of the mitochondrial cytochrome b gene of these parasites. We have found six lineages of Plasmodium (SGS1, GRW11, COLL1, DELURB4, GRW04 and BLUTI10) parasitizing the studied populations but we did not detect any infection by Haemoproteus. One of the detected lineages (BLUTI10) has not been previously described in any bird species and this is the first study recording lineages DELURB4 and GRW04 in blue tits. SGS1 (belonging to the morphospecies Plasmodium relictum) was the most frequent lineage (overall prevalence, 24 %), whereas the other lineages showed a much lower prevalence (<4 %). Only a small proportion (12.2 %) of positive amplifications of the most common lineage (SGS1) was detected in blood smears using light microscopy and infection intensities were very low (mean ± SE, 2.0 ± 1.4 parasites/2,000 erythrocytes). We have also found strong inter-population variability in prevalence patterns (12-41 % for lineage SGS1), suggesting important differences in parasite transmission rates among the geographically close studied localities.