Dirofilaria repens microfilariae in Aedes vexans mosquitoes in Slovakia

In this study, we screened field-caught mosquitoes for presence of Dirofilaria spp. by using a polymerase chain reaction (PCR) assay. Potential occurrence of Dirofilaria repens and Dirofilaria immitis microfilariae was examined in 3,600 mosquitoes of eight species (Aedes vexans, Aedes cinereus, Aedes rossicus, Culex pipiens, Culiseta annulata, Ochlerotatus sticticus, Ochlerotatus cantans and Ochlerotatus caspius) collected from five locations in two districts (Kosice and Trebisov) of Eastern Slovakia, endemic region of canine dirofilariasis. Collection of mosquitoes was performed between May and August 2012 in premises known to be inhabited by Dirofilaria-infected dogs. PCR assays were performed on 72 pools, each pool containing 50 mosquitoes of the same species, collected on the same location. Each pool was examined separately for the presence of D. immitis and D. repens, respectively. A positive finding of D. repens was recorded in one pool of A. vexans mosquitoes collected in Košické Olšany village. Minimum infection rate in A. vexans was 1:1,750, i.e. 0.57 per 1,000 mosquitoes. The identity of D. repens was confirmed by direct sequencing of PCR product which has shown 100% homology with sequence attributed to D. repens (GenBank accession number AJ271614). This study represents the first molecular evidence of D. repens microfilariae in mosquitoes in Slovakia and highlights a need for better surveillance of zoonotic dirofilariasis in central Europe.