Sand flies (Diptera: Psychodidae) in the Republic of Kosovo: Distribution Mapping, Ecology and Pathogen Circulation Hotspots

Abstract

During military deployments, soldiers are at risk of contracting diseases transmitted by medically relevant vectors (ticks, mosquitoes and sand flies) in endemic regions. Previous studies have detected antibodies against Leishmania and phleboviruses, in Austrian soldiers returning from Kosovo and Bosnia and Herzegovina; demonstrating a clear exposure to these pathogens. Phlebotomine sand flies (Diptera: Psychodidae) are small, hematophagous insects and the principal vectors of Leishmania spp. and phleboviruses. Both are endemic in the Balkans, but have long been understudied. This study aimed to assess and update the sand fly distribution in Kosovo, evaluate factors influencing their presence, and assess local pathogen circulation. Two sand fly surveys using CDC light traps were conducted in understudied regions of Kosovo in 2022 and 2023. Morphological identification was confirmed by barcoding, and host-feeding preferences were assessed by blood meal analyses. PCR-based methods and sequencing were used to screen for Leishmania spp. and phleboviruses. Additional occurrence data from two previous surveys were incorporated to generate distribution maps and evaluate environmental data. More than 3500 sand flies were trapped in seven regions of Kosovo with Ph. neglectus and Ph perfiliewi being the most prevalent. Barcodes of eight endemic species were generated and environmental analyses identified two geographical groups with notable differences between species. Blood meals of five sand fly species, identifying seven different host species. Leishmania DNA was amplified from two sand fly species, in both cases L. infantum, whereas RNA from three phlebovirus species was detected. This study provides the most comprehensive sand fly survey for the Kosovo to date, identifying factors influencing sand fly occurrence and potential hotspots of pathogen circulation, thus highlighting the need for targeted measures to mitigate the risk of vector-borne diseases in the region.