Exploring the vector potential of Lipoptena cervi (Diptera: Hippoboscidae): first record of Setaria cervi (Filarioidea: Onchocercidae) DNA in deer keds

<i>Setaria cervi</i> is a filarial nematode that infects both wild and domestic ungulates. It is primarily transmitted by mosquitoes, although the possible role of other hematophagous insects is still uncertain. We investigated 83 wingless deer keds (<i>Lipoptena</i> spp.) from red and fallow deer in northern and eastern Slovakia, as well as 43 red deer liver samples for the presence of filarial DNA. Deer keds were identified as <i>Lipoptena cervi</i> (<i>n</i> = 80) and <i>Lipoptena fortisetosa</i> (<i>n</i> = 3). Genomic DNA from individual ectoparasites was screened by PCR targeting a mitochondrial <i>cox</i>1 gene fragment of filaroid nematodes. Two L. <i>cervi</i> from red deer in Hrabušice (eastern Slovakia) tested positive for <i>S. cervi</i> DNA, with 100% sequence identity with worms recently isolated from Slovak game animals. Additionally, <i>S. cervi</i> DNA was detected in one liver from a red deer in the Vranov nad Topl'ou district. This study provides the first molecular evidence of <i>S. cervi</i> DNA in <i>L. cervi</i>, suggesting a potential role of deer keds in the transmission at the wildlife-livestock-vector interface.