Parasites of the haemosporidian genus Polychromophilus have exclusively been described in bats. These parasites belong to the diverse group of malaria parasites, and Polychromophilus presents the only haemosporidian taxon that infects mammalian hosts in tropical as well as in temperate climate zones. This study provides the first information of Polychromophilus parasites in the lesser Asiatic yellow bat (Scotophilus kuhlii) in Thailand, a common vespertilionid bat species distributed in South and Southeast Asia. The gametocyte blood stages of the parasites could not be assigned to a described morphospecies and molecular analysis revealed that these parasites might represent a distinct Polychromophilus species. In contrast to Plasmodium species, Polychromophilus parasites do not multiply in red blood cells and, thus, do not cause the clinical symptoms of malaria. Parasitological and molecular investigation of haemosporidian parasites of wildlife, such as the neglected genus Polychromophilus, will contribute to a better understanding of the evolution of malaria parasites.

Background Haemosporidian parasites of the genus Polychromophilus infect bats worldwide. They are vectored by obligate ectoparasitic bat flies of the family Nycteribiidae. Despite their global distribution, only five Polychromophilus morphospecies have been described to date. The two predominant species, Polychromophilus melanipherus and Polychromophilus murinus, are broadly distributed and mainly infect miniopterid and vespertilionid bats, respectively. In areas where species from different bat families aggregate together, the infection dynamics and ability of either Polychromophilus species to infect other host families is poorly characterized. Methods We collected 215 bat flies from two bat species, Miniopterus schreibersii and Rhinolophus ferrumequinum, which sometimes form mixed clusters in Serbia. Miniopterus schreibersii is known to be frequently infected with P. melanipherus, whereas R. ferrumequinum has been observed to be incidentally infected with both Polychromophilus species. All flies were screened for Polychromophilus infections using a PCR targeting the haemosporidian cytb gene. Positive samples were subsequently sequenced for 579 bp of cytochrome b (cytb) and 945 bp of cytochrome oxidase subunit 1 (cox1). Results Polychromophilus melanipherus DNA was detected at six out of nine sampling locations and in all three examined bat fly species collected from M. schreibersii (Nycteribia schmidlii, n = 21; Penicillidia conspicua, n = 8; Penicillidia dufourii, n = 3). Four and five haplotypes were found for cytb and cox1, respectively. Evidence for multiple Polychromophilus haplotypes was found in 15 individual flies. These results point to a high diversity of P. melanipherus parasites in Miniopterus hosts and efficient transmission throughout the study area. A single Phthiridium biarticulatum bat fly collected from R. ferrumequinum screened positive for P. melanipherus, but only yielded a partial cox1 sequence fragment. Nevertheless, this result suggests that secondary hosts (both bat and fly species) are regularly confronted with this parasite. Conclusions The results of this study provide new insights into the prevalence and distribution of Polychromophilus parasites in European bats and their nycteribiid vectors. The use of bat flies for the non-invasive investigation of Polychromophilus infections in bat populations has proven to be efficient and thus represents an alternative for large-scale studies of infections in bat populations without the need to invasively collect blood from bats. Graphical Abstract

Bats are mammalian hosts to a large diversity of eukaryotic protozoan blood parasites, including different genera of haemosporidians and diverse species of trypanosomes. Phylogenetic studies suggest that bats, particularly in Africa, have played an important role in the evolutionary histories of these parasite groups. However, our understanding of the diversity and distribution of chiropteran haemosporidians and trypanosomes in Africa remains tenuous. We investigated the prevalence and phylogenetic relationships of the blood parasites in different bat species in Northern Nigeria using molecular methods. A low prevalence of Hepatocystis parasites was detected in a potentially rare host species, the African straw-coloured fruit bat (Eidolon helvum) confirming yet another fruit bat species in the diverse range of African bat hosts. Trypanosome infections were identified in 3 different bat species. The trypanosomes of Mops cf. pumilus were recovered as a distinct lineage that is related to Trypanosoma erneyi, a species which is closely related to Trypanosoma dionisii and Trypanosoma cruzi. Nycteris cf. macrotis bats were infected with trypanosomes that are related to the distinct lineage of Trypanosoma cf. livingstonei parasites. Further, 2 different lineages of trypanosomes in E. helvum bats share highest nucleotide identities with Trypanosoma livingstonei and a group of Trypanosoma sp. parasites that are closely related to T. cf. livingstonei and T. livingstonei, respectively. The findings of this study confirm the notion that trypanosomes of African bats are phylogenetically diverse and that African bats might harbour a variety of yet undescribed trypanosome species.