Molecular Screening of Black Flies (Diptera: Simuliidae) for Vector-Borne Zoonotic Pathogens, South Moravia, Czech...

Black flies (Simuliidae) are globally distributed blood-feeding arthropods and vectors of viral, bacterial, and parasitic pathogens to many animal species, including humans. We investigated the occurrence of selected vector-borne pathogens in black flies in South Moravia, Czech Republic, and evaluated their possible role in the circulation of vector-borne pathogens.

A total of 11,600 black flies comprising four species of the genus Simulium, namely Simulium (Boophthora) erythrocephalum (De Geer, 1776), Simulium (Wilhelmia) lineatum (Meigen, 1804), Simulium (Wilhelmia) balcanicum (Enderlein, 1924), and Simulium (Wilhelmia) turgaicum (Rubtsov, 1940) were pooled and screened for the following arthropod-borne pathogens and parasites endemic in Central Europe: viruses (alphaviruses, bunyaviruses and flaviviruses), bacteria (Borrelia burgdorferi sensu lato, Borrelia miyamotoi, Anaplasma phagocytophilum, Neoehrlichia mikurensis, Bartonella spp., Rickettsia spp., Francisella tularensis, Coxiella burnetii, and Brucella spp.), protista (Babesia spp., Encephalitozoon spp. and Enterocytozoon spp.) and filaria (Dirofilaria spp., Setaria spp., and Onchocerca spp.).

Almost all pools were negative for known arthropod-borne pathogens and parasites. However, four new Bartonella spp. variants were found that share similarity with other bartonellae reported from diverse arthropods and humans. The phylogenetic analysis of Bartonella sequences from Czech black flies provides further evidence about an expanding diversity of Bartonella lineages in arthropods globally, including hematophagous species (e.g., ticks, mosquitoes, and biting flies) and non-hematophagous species (e.g., bees and ants). These bartonellae have the potential to cause pathogenic infections in humans who are exposed to arthropods carrying these bacteria.

Summing up, this study provides for the very first time valuable data for characterising the risk to public and veterinary health from black flies and the infections they may carry in Europe. Further testing, however, should include a wider geographic, seasonal, and taxonomic range of black flies.