Sandfly surveillance and investigation of Leishmania spp. DNA in sandflies in Kosovo

Combining phylogeography and climate models to track the diversification and spread of Phlebotomus simici

Phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae) are the principal vectors of Leishmania spp. (Kinetoplastida: Trypanosomatidae) worldwide. The subgenus Adlerius is taxonomically challenging and currently comprises about 20 species with a wide geographic distribution from eastern Asia to southeastern Europe. Some species are confirmed or suspected vectors of Leishmania donovani/infantum, L. major, and L. tropica, and are thus of high medical and veterinary relevance. A single record of Phlebotomus (Adlerius) simici in Austria from 2018 marks its sporadic northernmost and westernmost occurrence, with the origin of its appearance remaining unclear. To better understand Adlerius diversification and particularly post-glacial spread of Ph. simici to northern parts of Europe, we combined phylogenetic analyses with climatic suitability modelling. Divergence time estimates well supported the currently observed geographic distribution of the studied species and revealed several taxonomic challenges in the subgenus. We clearly delineated three distinct genetic and geographic Ph. simici lineages and phylogeographically assessed diversification that were well supported by climatic models. This study provides a comprehensive phylogenetic analysis of the subgenus Adlerius, enhancing our understanding of the diversification in relation to changing climate of this understudied group, and we present new insights into the post-glacial spread of Ph. simici, a suspected vector of L. infantum.

A cross-sectional study on phlebotomine sand flies in relation to disease transmission in the Republic of Kosovo

Sand flies (Diptera: Psychodidae: Phlebotominae) are blood-feeding insects that transmit the protozoan parasites Leishmania spp. and various arboviruses. The Balkan region, including the Republic of Kosovo, harbours a diverse sand fly fauna. Vector species of Leishmania infantum as well as phleboviruses are endemic; however, recent data are scarce. We performed a cross-sectional study to update the current sand fly distribution in Kosovo and assess biological as well as environmental factors associated with sand fly presence. CDC light trapping was conducted at 46 locations in 2022 and 2023, specifically targeting understudied regions in Kosovo. Individual morphological species identification was supported by molecular barcoding. The occurrence data of sand flies was used to create distribution maps and perform environmental analyses, taking elevation, wind speed and climate-related factors into account. In addition, PCR-based blood meal analysis and pathogen screening were conducted. Overall, 303 specimens of six sand fly species were trapped, predominated by Phlebotomus neglectus (97%). Barcodes from eight of nine known endemic sand fly species were obtained. Combining our data with previous surveys, we mapped the currently known sand fly distribution based on more than 4000 specimens at 177 data points, identifying Ph. neglectus and Ph. perfiliewi as the predominant species. Environmental analyses depicted two geographical groups of sand flies in Kosovo, with notable differences between the species. In total, 223 blood meals of five sand fly species were analysed. Of seven identified host species, the predominant blood meal source was observed to be cattle, but the DNA of dogs and humans, among others, was also detected. This study assessed biological as well as ecological factors of sand fly occurrence, which should help better understand and evaluate potential hot spots of disease transmission in Kosovo.

Ecological setting of phlebotomine sand flies in the Republic of Kosovo

Sand flies (Diptera, Psychodidae) are the principal vectors of Leishmania spp., the causative agents of leishmaniasis, as well as phleboviruses. In the Balkans, the endemicity and spreading of sand fly-borne diseases are evident, particularly in the Republic of Kosovo, a country with a predominantly humid continental climate. To date, understanding the drivers behind the spatial structure and diversity patterns of sand fly communities in humid continental regions remains limited. Therefore, elucidating the geographical and ecological factors contributing to the presence of potential vector species in the country is crucial. We aimed to enhance our understanding of factors influencing sand fly occurrence in cool and wet wintering humid continental areas, which could serve as a model for other countries with similar climatic conditions. Therefore, we assessed the currently known sand fly fauna through detailed environmental analyses, including Voronoi tessellation patterns, entropy calculations, Principal Coordinate and Component Analyses, Hierarchical Clustering, Random Trees, and climatic suitability patterns. Notable differences in the ecological tolerance of the species were detected, and the most important climatic features limiting sand fly presence were wind speed and temperature seasonality. Sand flies were observed to prefer topographical environments with little roughness, and the modelled climatic suitability values indicated that, dominantly, the western plain regions of Kosovo harbour the most diverse sand fly fauna; and are the most threatened by sand fly-borne diseases. Phlebotomus neglectus and P. perfiliewi, both confirmed vectors for L. infantum and phleboviruses, were identified as two main species with vast distribution in Kosovo. Contrary to this, most other present species are relatively sparse and restricted to temperate rather than humid continental regions. Our findings reveal a diverse potential sand fly fauna in Kosovo, indicating the need for tailored strategies to address varying risks across the country's western and eastern regions in relation to leishmaniasis control amidst changing environmental conditions.

First Detection and Molecular Analysis of Leishmania infantum DNA in Sand Flies of Kosovo

Phlebotomine sand flies (Diptera: Psychodidae) are the principal vectors of phleboviruses and Leishmania spp., the causative agents of leishmaniases. The Mediterranean sand fly fauna is diverse, and leishmaniasis, mainly caused by Leishmania infantum, is endemic in the Balkan countries. Despite recent entomological surveys, only some districts of Kosovo have been sampled for sand flies, with no proof/confirmation of L. infantum. This study aimed to gain further insights into the species composition of natural sand fly populations in previously unsampled districts and areas in Kosovo without reports of leishmaniasis and to detect Leishmania DNA in sand flies. A sand fly survey was conducted in 2022 in all seven districts of Kosovo. Collected females were screened for Leishmania DNA by PCR. Positive samples were sequenced and subjected to maximum likelihood analysis with reference sequences for further molecular characterization. The trapping activities at 114 different localities resulted in 3272 caught specimens, comprising seven sand fly species of two genera, namely Phlebotomus neglectus, Ph. perfiliewi, Ph. tobbi, Ph. papatasi, Ph. simici, Ph. balcanicus and Sergentomyia minuta. Leishmania infantum DNA was detected in three individual sand flies of Ph. neglectus and Ph. perfiliewi. This study provides the most extensive sand fly survey in Kosovo and reports the first record of L. infantum DNA in sand flies, indicating autochthonous circulation of L. infantum.

Seroprevalence of canine leishmaniosis in asymptomatic dogs in Kosovo

Canine leishmaniosis (CanL) is a neglected zoonotic disease caused by Leishmania spp. Leishmania infantum is the species responsible for the zoonotic form of the disease where dogs are reservoir hosts. This study aimed to determine the seroprevalence of CanL in asymptomatic dogs in Kosovo. Blood samples were collected from 285 dogs in all seven regions in Kosovo (35-50 samples per region) from summer 2021 to spring 2022. Sera were tested using enzyme-linked immunosorbent assay (ELISA), and the presence of anti-Leishmania IgG was confirmed by an indirect fluorescent antibody test (IFAT). The true overall seroprevalence of CanL of asymptomatic dogs in Kosovo with ELISA was 4.21% (95% CI: 2.42-7.21) while with IFAT was 3.51% (95% CI: 1.92-6.34). The highest rates were found in the Prishtina region to be 8.0% (4/50) by ELISA and 6.0% (3/50) by IFAT, and in the Mitrovica region, the prevalence was 0% (0/40). There were no significant differences among the different regions, gender, age, health status, and breed. These findings highlight the presence of CanL in most regions of Kosovo and underline the veterinary relevance of clinically asymptomatic dogs infected with Leishmania.

Canine leishmaniasis in Balkan - A review of occurrence and epidemiology

Canine leishmaniasis is a parasitic zoonotic infection of dogs caused by the Leishmania spp. parasites. In Europe, canine leishmaniasis is among the most important vector-borne parasitic diseases of dogs, with majority of data originating from countries of southwestern Europe. With its scarce and outdated records, the Balkan region presents the "blank space" in the European map of canine leishmaniasis knowledge. Numerous records obtained during the past decade and a half indicate the emergence of autochthonous canine leishmaniasis in new settings all across Balkan, a significant increase in the numbers of infected dogs in previously endemic areas, and northward spread of the disease. As the majority of canine leishmaniasis data from Balkan countries are several decades old and generally written in native Balkan languages, hence not available to the broader area of scientists, comprehensive search of scientific literature published from 1934 to January 2021 was conducted in order to provide a better perspective to the past and current canine leishmaniasis situation in Balkan. This review provides exhaustive information on all leishmaniasis records in dogs, wild animals and cats, available from 10 countries of the Balkan region. It identifies dogs as the main disease reservoirs and highlights the importance of wild animals, and potentially cats, as disease reservoirs, which is of great public and veterinary health concern. Additionally, certain shortcomings in canine leishmaniasis research, management, surveillance and control were identified.

Systematic Review: Re-emergence of human leishmaniasis in the Balkans

OBJECTIVE

To provide an updated overview of the leishmaniasis epidemiology in the Balkans, as this region presents "blank space" on the map of leishmaniasis knowledge in Europe.

METHODS

Following the PRISMA guideline, literature on the presence and circulation of human leishmaniasis in Balkan countries was screened in PubMed, Google Scholar, Science Direct, Scopus, Web of Science, Matica Srpska Library and the National Library of Serbia.

RESULTS

Sixty nine publications from 1919 until September 2020 were reviewed. Historical records indicate that leishmaniasis was previously present mainly in the southern parts of the Balkans, while newer data demonstrate its northward spread.

CONCLUSIONS

Human leishmaniasis is re-emerging in the Balkans and in some areas is already widespread.

First molecular identification of Leishmania major in Phlebotomus papatasi in an outbreak cutaneous leishmaniasis area in Iraq

Cutaneous leishmaniasis (CL) is transmitted by Phlebotomine sand fly vectors, among which Phlebotomus papatasi is prevalent in Western Asia, Northern Africa and Southern Europe, and it is known as a vector for Leishmania major parasite in the world. However, in Iraq, morphological studies showed that P. papatasi is a predominant sand fly species and hypothesised to transmit CL causing Leishmania species including L. major and L. tropica. Few studies have found Leishmania species in sand flies in mixed pools of samples in this country. Accurate identification of sand flies as vectors of Leishmania species is required in Iraq. The current study aims to identify sand fly species, using both morphological and molecular phylogenetic analyses, in a region where CL tends to be endemic. Furthermore, molecular phylogenetic analysis has also used to confirm Leishmania species in the sand fly samples collected in 11 villages between Diyala and Sulaymaniyah Provinces. For the first time, we have found L. major in three individual sand flies, one engorged (with fresh blood meal) and two non-engorged (without visible fresh blood meal) P. papatasi females in an area of CL outbreaks since 2014-till now due to civil wars and internal conflicts happen in the region. Further study should be performed on sand fly population and Leishmania reservoirs in this region.

Phlebotomus (Adlerius) simici NITZULESCU, 1931: first record in Austria and phylogenetic relationship with other Adlerius species

Background

Phlebotomine sand flies are the principal vectors of Leishmania spp. (Kinetoplastida: Trypanosomatidae). Information on sand flies in Central Europe is scarce and, to date, in Austria, only Phlebotomus mascittii has been recorded. In 2018 and 2019, entomological surveys were conducted in Austria with the aim to further clarify sand fly distribution and species composition.

Results

In 2019, a Ph. simici specimen was trapped in Austria for the first time. Analyses of two commonly used marker genes, cytochrome c oxidase I (coxI) and cytochrome b (cytb), revealed high sequence identity with Ph. simici specimens from North Macedonia and Greece. Phylogenetic analyses showed high intraspecific distances within Ph. simici, thereby dividing this species into three lineages: one each from Europe, Turkey and Israel. Low interspecific distances between Ph. simici, Ph. brevis and an as yet unidentified Adlerius sp. from Turkey and Armenia highlight how challenging molecular identification within the Adlerius complex can be, even when standard marker genes are applied.

Conclusion

To our knowledge, this study reports the first finding of Ph. simici in Austria, representing the northernmost recording of this species to date. Moreover, it reveals valuable insights into the phylogenetic relationships among species within the subgenus Adlerius. Phlebotomus simici is a suspected vector of L. infantum and therefore of medical and veterinary importance. Potential sand fly expansion in Central Europe due to climatic change and the increasing import of Leishmania-infected dogs from endemic areas support the need for further studies on sand fly distribution in Austria and Central Europe in general.

Graphic abstract