Diversity of filariae circulating in South Caucasian bats and their ectoparasites

Recent research on chiropteran parasites suggests a high prevalence and diversity, and extensive spatial distribution of filarial species; however, ecological and phylogenetic studies are still in their infancy. We sampled blood from 78 bat specimens, collected 1181 ectoparasites at summer colonies in Armenia and Georgia, and used nested-PCR targeting the cytochrome c oxidase subunit 1 (cox1) gene to detect and genotype filarial parasites. The overall prevalence of filarial DNA was 17.9% in blood samples from Myotis blythii, Myotis emarginatus, Miniopterus schreibersii, and Rhinolophus ferrumequinum, and 8.5% in ectoparasites, including two mite species (Eyndhovenia euryalis and Spinturnix myoti) and two bat flies (Nycteribia kolenatii and Penicillidia dufouri). The prevalence of microfilarial infection was significantly higher in mite samples (13.8%) than in bat fly samples (4.1%). Bats with ectoparasites positive for filarial DNA had a significantly higher total number of ectoparasites. Phylogenetic analysis placed the 18 sequences obtained into different closely related clades of onchocercid nematodes, with four different species recorded: two belonging to the genus Litomosa and two to a newly observed genus of the family Onchocercidae. Additionally, two new species of these parasites, one Litomosa sp. and one Onchocercid sp., were genetically recognised. As predicted, the diversity of filarial parasites reflects the diversity of bat hosts in the Caucasus. Extending the sampling effort to more Caucasian bat species will likely reveal previously unknown filarial species. Non-lethal and non-invasive sampling of blood and ectoparasites for molecular screening proved effective for gaining insights into parasite diversity and phylogenetic relationships of bat-infecting filarial nematodes.