Phlebotomine sand flies in Southwest Germany: an update with records in new locations

Prevalence of Toscana Virus Antibodies in Residents of Bulgaria: A Nationwide Study Following the Pandemic of COVID-19

Introduction: Toscana virus (TOSV) is an arthropod-borne virus transmitted by sandflies and is mainly found in countries around the Mediterranean basin. In this article, we present the findings of a seroprevalence study on TOSV in Bulgaria. We aim to assess the current epidemiological situation regarding TOSV in the country and raise clinical awareness. Methods: Serum samples (n = 1892) were collected in December 2023. Serological tests were performed using a commercial anti-TOSV ELISA kit. Results: Specific immunoglobulin G (IgG) antibodies were detected in 6.4% (121/1892) of the participants. A significantly higher seropositivity rate was found in the age group over 65 years compared with the age groups 18-29 and 40-64 (11.8% vs. 3.9% vs. 3.4%), as well as in males compared with females (8.0% vs. 5.3%). The seroprevalence rates in districts ranged from 0% to 18.5%. Higher seropositivity was found in the southern and northern regions. Conclusions: The seroprevalence rate of TOSV in Bulgaria, found in this study, is a significant decrease compared with the seropositivity rate of 24.5% reported in the country in 2018. The reasons for this are unknown and could possibly be related to the COVID-19 pandemic and the constantly changing environmental conditions. There is also a possibility that the higher seropositivity detected in 2018 together with the rise in clinical cases reported from endemic countries around that time might have been due to an unrecognized TOSV outbreak taking place in this period. Continued clinical awareness and surveillance are necessary for recognition and management of potential cases of TOSV neuroinfection, especially during summer.

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.

Sand flies and Toscana virus: Intra-vector infection dynamics and impact on Phlebotomus perniciosus life-history traits

Toscana virus (TOSV) is a leading cause of summer viral meningitis in Southern Europe (Central Italy, south of France, Spain and Portugal) and can cause severe neurological cases. Within the Mediterranean basin, it is transmitted by hematophagous sand flies belonging to the Phlebotomus genus. Despite the identification of the primary TOSV vectors, the viral developmental cycle in vector species remains largely unknown. Limited research has been conducted on transmission dynamics and the vector competence and vectorial capacity of the principal TOSV vector, Phlebotomus perniciosus. In this context, we investigated the intra-vector TOSV infection dynamics in Ph. perniciosus, as well as its impact on the vector life history traits. Female sand flies were experimentally infected with TOSV through an artificial blood meal. Systemic dissemination of the virus was observed approximately three days post-infection, potentially resulting in a short extrinsic incubation period. Moreover, the study revealed a longer hatching time for eggs laid by infected females. This research brought additional experimental insights regarding the vector competence of Ph. perniciosus but also provided the first insight into TOSV developmental cycle and its impact on the vector. These findings prompt further exploration of TOSV transmission dynamics, raise new hypotheses on the virus transmission and highlight the importance of follow-up studies.

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 Evidence of Leishmania infantum Antibodies in Sheep (Ovis aries) from Southern Germany

In Europe, Leishmania infantum is the most prevalent Leishmania species, and this protozoan is transmitted by phlebotomine sandflies. A recent publication has shown that sheep harbor L. infantum antibodies. This raises questions about the epidemiological role of small ruminants. Therefore, sera from small ruminants located in two southern German federal states, Baden-Wuerttemberg (BW) and Bavaria (BAV), were analyzed with an ELISA to determine the presence of L. infantum antibodies. The species, sex and age (gimmer vs. ewe) were recorded, and a univariate analysis was conducted to determine possible associations. In total, seven sheep flocks (274 sheep/10 goats) from BW and seven sheep flocks (277 sheep/78 goats) from BAV were examined. In BW, four sheep from three flocks tested positive for L. infantum antibodies. In BAV, the same number of positive sheep were detected but in four flocks. The total seropositivity rate in sheep was 1.45%. All goats tested negative. No significant association (p > 0.05) was detected between Leishmania seropositivity and the variables evaluated. Our study reveals the exposure of sheep to L. infantum in a non-endemic area. Further investigation is needed to determine whether sheep can be used as sentinels to identify new phlebotomine habitats and Leishmania risk areas.

Meteorological, demographic, and environmental risk factors for Leishmania infantum in wildlife

Leishmania infantum is an important and neglected vector-borne zoonotic protozoa endemic in the Mediterranean basin. Several wild and domestic mammals can contribute to maintaining its circulation but their importance as effective reservoirs is still under discussion and varies depending on local ecological communities. By combining environmental, climatic, and individual information, this study assessed the presence of L. infantum DNA in a set of wild species from Northwestern Italy and the potential ecological factors related to the risk of infection. From 2020 to 2022, 304 free-ranging wild animals were analyzed for the detection of L. infantum DNA in the spleen and popliteal lymph node (when available). The prevalence obtained in wild boar (Sus scrofa) and roe deer (Capreolus capreolus) was higher than those previously reported (% ± confidence interval 95%; 42.9 ± 18.4% and 27 ± 6.6% in wild boar and roe deer, respectively), and this is the first report of this parasite infecting the coypu Myocastor coypus (60 ± 34.7%). L. infantum DNA was detected in all the seasons including those free of adult sandflies and seasonal differences were minimal, suggesting a long course of infection. The models revealed that animals from rainy areas with higher greenness during the summer, highly populated by humans and predominantly covered by water surfaces had a higher risk of L. infantum. This study contributes to confirming previous findings on the existence of a sylvatic cycle for L. infantum in certain regions of Italy, as well as on the potential epidemiological role of roe deer for this parasite given the elevated prevalence found.

The Impact of Climatological Factors on the Incidence of Cutaneous Leishmaniasis (CL) in Colombian Municipalities from 2017 to 2019

Cutaneous leishmaniasis (CL) is a zoonotic disease caused by protozoa of the Leishmania genus, transmitted by vectors from the Phlebotominae subfamily. The interaction between the vector, reservoir, and parasite is susceptible to climate change. This study explores how temperature and rainfall influenced the incidence of CL in 15 Colombian municipalities between 2017 and 2019. Epidemiological data were obtained from Colombia's Instituto Nacional de Salud, while climatological data came from the Instituto de Hidrología, Meteorología y Estudios Ambientales. Using Spearman's rank correlation coefficient, we examined the relationships between monthly climatic variables and the cumulative incidence of CL, considering various lag times. The data were further analyzed using Locally Weighted Scatterplot Smoothing (LOWESS). Our findings reveal both significant positive and negative correlations, depending on locality and climate variables. LOWESS analysis indicates that while rainfall-related incidence remains stable, temperature impacts incidence in a parabolic trend. This study underscores the significant yet complex influence of climatic factors on CL incidence. The insights gained could aid public health efforts by improving predictive models and crafting targeted interventions to mitigate the disease's impact, particularly in regions vulnerable to climate variability.

The Phlebotomine sand fly fauna of Switzerland revisited

Sand flies (Diptera: Psychodidae, Phlebotominae; Newstead, 1911) are widespread in Europe, being particularly common in the Mediterranean region but rare north of the Alps. Thus, Switzerland is an opportune place to investigate the sand fly fauna on both sides of the Alpine crest, in southern sub-Mediterranean climate and northern oceanic temperate climate. We reinvestigated the Swiss sand fly fauna with the aim to assess changes in composition, altitudinal distribution, abundance and seasonality. Thirty-eight sites were investigated with light traps and/or interception sticky traps in 4 years. Ninety and 380 specimens were caught by light traps and sticky traps, respectively, at 15 collecting sites. Four species were identified. Phlebotomus mascittii (Grassi, 1908), Phlebotomus perniciosus (Newstead, 1911) and Sergentomyia minuta (Rondani, 1843) were confirmed in Ticino, and P. mascittii for the first time in neighbouring Grisons. Also, Phlebotomus neglectus (Tonnoir, 1921) is for the first time reported, though at a very low density compared to P. perniciosus at the same site. Its presence in Ticino supports the northward spread observed in Italy. Sand flies were detected north of the Alps at one site only, endorsing a historical report. Overall, the low density of P. perniciosus and very low density of P. neglectus suggest that canine leishmaniosis may not be an important disease risk in Switzerland.

Comparative Study of a Novel Lateral Flow Rapid Test with Conventional Serological Test Systems for the Diagnosis of Canine Leishmaniosis in Croatia and Brazil

Control of canine infections with Leishmania infantum (L. infantum), a major zoonotic disease in Brazil and southern Europe, is becoming increasingly important due to its close proximity to humans, the increasing import of dogs from endemic regions and the impact of climate change on vector spreading. Simple, rapid and reliable diagnostic tests are therefore needed to detect infected dogs. Here, we re-evaluated different serological methods for the diagnosis of canine leishmaniosis (CanL) in Croatia and Brazil. The diagnostic performance of the indirect fluorescent antibody test (IFAT) and the VetLine® Leishmania ELISA (GSD Frankfurt, Germany) was compared with three rKLi8.3-based diagnostic test systems, the rKLi8.3 ELISA (GSD Frankfurt, Germany), the INgezim® Leishma CROM (GSD Madrid, Spain) lateral flow test (LFT) and the VetBlot®Leishmania LineBlot (GSD Frankfurt, Germany). CanL symptomatic dogs were efficiently diagnosed by all tests, except the VetLine® Leishmania ELISA, which is based on whole Leishmania antigens. The advantage of rKLi8.3 was also observed in oligo- and asymptomatic dogs from Brazil and Croatia, although with reduced diagnostic efficiency compared to symptomatic dogs. Similar to IFAT and rKLi8.3 ELISA, the LFT did not cross-react with other common canine pathogens; it showed very high specificity for healthy dogs from endemic regions in both countries and did not react with healthy, vaccinated dogs in Brazil. In conclusion, serodiagnostic tests based on the rKLi8.3 antigens are superior to whole parasite antigens, and the LFT has the advantage of providing a laboratory-independent, rapid and specific diagnosis of CanL.

Reconstructing the post-glacial spread of the sand fly Phlebotomus mascittii Grassi, 1908 (Diptera: Psychodidae) in Europe

Phlebotomine sand flies (Diptera: Phlebotominae) are the principal vectors of Leishmania spp. (Kinetoplastida: Trypanosomatidae). In Central Europe, Phlebotomus mascittii is the predominant species, but largely understudied. To better understand factors driving its current distribution, we infer patterns of genetic diversity by testing for signals of population expansion based on two mitochondrial genes and model current and past climate and habitat suitability for seven post-glacial maximum periods, taking 19 climatic variables into account. Consequently, we elucidate their connections by environmental-geographical network analysis. Most analyzed populations share a main haplotype tracing back to a single glacial maximum refuge area on the Mediterranean coasts of South France, which is supported by network analysis. The rapid range expansion of Ph. mascittii likely started in the early mid-Holocene epoch until today and its spread possibly followed two routes. The first one was through northern France to Germany and then Belgium, and the second across the Ligurian coast through present-day Slovenia to Austria, toward the northern Balkans. Here we present a combined approach to reveal glacial refugia and post-glacial spread of Ph. mascittii and observed discrepancies between the modelled and the current known distribution might reveal yet overlooked populations and potential further spread.

Is leishmaniasis the new emerging zoonosis in the world?

Leishmania is a genus of parasitic protozoa that causes a disease called leishmaniasis. Leishmaniasis is transmitted to humans through the bites of infected female sandflies. There are several different species of Leishmania that can cause various forms of the disease, and the symptoms can range from mild to severe, depending on species of Leishmania involved and the immune response of the host. Leishmania parasites have a variety of reservoirs, including humans, domestic animals, horses, rodents, wild animals, birds, and reptiles. Leishmaniasis is endemic of 90 countries, mainly in South American, East and West Africa, Mediterranean region, Indian subcontinent, and Central Asia. In recent years, cases have been detected in other countries, and it is already an infection present throughout the world. The increase in temperatures due to climate change makes it possible for sandflies to appear in countries with traditionally colder regions, and the easy movement of people and animals today, facilitate the appearance of Leishmania species in new countries. These data mean that leishmaniasis will probably become an emerging zoonosis and a public health problem in the coming years, which we must consider controlling it from a One Health point of view. This review summarizes the prevalence of Leishmania spp. around the world and the current knowledge regarding the animals that could be reservoirs of the parasite.

Prevalence and Factors Related to Leishmania infantum Infection in Healthy Horses (Equus caballus) from Eastern Spain

Leishmaniosis is a zoonosis caused by Leishmania spp., an intracellular protozoan parasite. This parasite is transmitted by sandflies, and the disease is endemic in the Mediterranean basin. In recent years, the number of species which could be a reservoir of the parasite is increased. One of the most relevant species is the horse, due to their contact with humans and ability to control the disease, thus being a possible silent reservoir. In this study, we have analyzed the prevalence and factors related to L. infantum infection in healthy horses in the Mediterranean region. Epidemiological data and serum samples were obtained from 167 apparently healthy horses, and the presence of L. infantum was evaluated via the ELISA method and real-time PCR. The results show 27.5% of prevalence and that the main factors related to infection are equine breed, morphotype, outdoor living, use, and season. In conclusion, the prevalence of L. infantum infection in apparently healthy horses from eastern Spain (Mediterranean basin) is elevated. To control this zoonosis, it would be advisable to carry out more studies on this and other species that could be silent reservoirs of the parasite, as well as carry out measures such as the use of repellents on a regular basis.

Spatio-Temporal Pattern and Meteo-Climatic Determinants of Visceral Leishmaniasis in Italy

Historically, visceral leishmaniasis (VL) in Italy was constrained to Mediterranean areas. However, in the last 20 years, sand fly vectors and human cases of VL have been detected in northern Italy, traditionally classified as a cold area unsuitable for sand fly survival. We aim to study the spatio-temporal pattern and climatic determinants of VL incidence in Italy. National Hospital Discharge Register records were used to identify incident cases of VL between 2009 and 2016. Incident rates were computed for each year (N = 8) and for each province (N = 110). Data on mean temperature and cumulative precipitation were obtained from the ERA5-Land re-analysis. Age- and sex-standardized incidence rates were modeled with Bayesian spatial and spatio-temporal conditional autoregressive Poisson models in relation to the meteo-climatic parameters. Statistical inference was based on Monte Carlo−Markov chains. We identified 1123 VL cases (incidence rate: 2.4 cases/1,000,000 person-years). The highest incidence rates were observed in southern Italy, even though some areas of northern Italy experienced high incidence rates. Overall, in the spatial analysis, VL incidence rates were positively associated with average air temperatures (β for 1 °C increase in average mean average temperature: 0.14; 95% credible intervals (CrI): 0.01, 0.27) and inversely associated with average precipitation (β for 20 mm increase in average summer cumulative precipitation: −0.28, 95% CrI: −0.42, −0.13). In the spatio-temporal analysis, no association between VL cases and season-year specific temperature and precipitation anomalies was detected. Our findings indicate that VL is endemic in the whole Italian peninsula and that climatic factors, such as air temperature and precipitation, might play a relevant role in shaping the geographical distribution of VL cases. These results support that climate change might affect leishmaniasis distribution in the future.

Current Applications of Plant-Based Drug Delivery Nano Systems for Leishmaniasis Treatment

Leishmania is a trypanosomatid that causes leishmaniasis. It is transmitted to vertebrate hosts during the blood meal of phlebotomine sandflies. The clinical manifestations of the disease are associated with several factors, such as the Leishmania species, virulence and pathogenicity, the host-parasite relationship, and the host's immune system. Although its causative agents have been known and studied for decades, there have been few advances in the chemotherapy of leishmaniasis. The urgency of more selective and less toxic alternatives for the treatment of leishmaniasis leads to research focused on the study of new pharmaceuticals, improvement of existing drugs, and new routes of drug administration. Natural resources of plant origin are promising sources of bioactive substances, and the use of ethnopharmacology and folk medicine leads to interest in studying new medications from phytocomplexes. However, the intrinsic low water solubility of plant derivatives is an obstacle to developing a therapeutic product. Nanotechnology could help overcome these obstacles by improving the availability of common substances in water. To contribute to this scenario, this article provides a review of nanocarriers developed for delivering plant-extracted compounds to treat clinical forms of leishmaniasis and critically analyzing them and pointing out the future perspectives for their application.

Arbovirus Epidemiology: The Mystery of Unnoticed Epidemics in Ghana, West Africa

It is evident that all the countries surrounding Ghana have experienced epidemics of key arboviruses of medical importance, such as the recent dengue fever epidemic in Burkina Faso. Therefore, Ghana is considered a ripe zone for epidemics of arboviruses, mainly dengue. Surprisingly, Ghana never experienced the propounded deadly dengue epidemic. Indeed, it is mysterious because the mosquito vectors capable of transmitting the dengue virus, such as Aedes aegypti, were identified in Ghana through entomological investigations. Additionally, cases may be missed, as the diagnostic and surveillance capacities of the country are weak. Therefore, we review the arbovirus situation and outline probable reasons for the epidemic mystery in the country. Most of the recorded cases of arbovirus infections were usually investigated via serology by detecting IgM and IgG immunoglobulins in clinical samples, which is indicative of prior exposure but not an active case. This led to the identification of yellow fever virus and dengue virus as the main circulating arboviruses among the Ghanaian population. However, major yellow fever epidemics were reported for over a decade. It is important to note that the reviewed arboviruses were not frequently detected in the vectors. The data highlight the necessity of strengthening the diagnostics and the need for continuous arbovirus and vector surveillance to provide an early warning system for future arbovirus epidemics.

Sandfly-Borne Phleboviruses in Portugal: Four and Still Counting

According to ICTV, there are currently 66 known phlebovirus species. More than 40 of these viruses were isolated or detected in phlebotomine sandflies and some of them are known pathogens. In Portugal, information about sandfly-borne phleboviruses is scarce and scattered sandfly-borne diseases are neglected and often not considered in differential diagnoses. The main objective of this work was to gather the existing information and to raise awareness about the circulating phleboviruses in this country. To date, Massilia and Alcube phleboviruses have been isolated from sandflies in southern Portugal. Human infections with Toscana and Sicilian phleboviruses have been reported, as well as seroprevalence in cats and dogs. More studies are needed in order to understand if the viruses isolated during the entomological surveys have an impact on human health and to fully understand the real importance of the already recognized pathogens in our country.

Canine Leishmaniasis: Update on Epidemiology, Diagnosis, Treatment, and Prevention

Dog are the main reservoir of Leishmania infantum, causing canine leishmaniasis, an incurable multisystemic disease that leads to death in symptomatic dogs, when not treated. This parasite causes visceral, cutaneous, and mucosal leishmaniasis in people in the Mediterranean Basin, North Africa, South America, and West Asia. This disease is mostly unknown by veterinarians outside the endemic areas, but the disease is expanding in the Northern Hemisphere due to travel and climate change. New methodologies to study the epidemiology of the disease have found new hosts of leishmaniasis and drawn a completely new picture of the parasite biological cycle. Canine leishmaniasis diagnosis has evolved over the years through the analysis of new samples using novel molecular techniques. Given the neglected nature of leishmaniasis, progress in drug discovery is slow, and the few drugs that reach clinical stages in humans are unlikely to be commercialised for dogs, but several approaches have been developed to support chemotherapy. New-generation vaccines developed during the last decade are now widely used, along with novel prevention strategies. The implications of the epidemiology, diagnosis, treatment, and prevention of canine leishmaniasis are fundamental to public health.

Seropositivity of main vector-borne pathogens in dogs across Europe

BACKGROUND

Canine vector-borne disease (CVBD) has been an area of increasing interest in Europe over the last few decades, and there have been changes in the prevalence and distribution of many of these diseases. Monitoring CVBD infections in Europe is often done by individual countries, but aggregated data for the European countries are helpful to understand the distribution of CVBDs.

METHODS

We used an extensive retrospective database of results from point-of-care rapid enzyme-linked immunosorbent assay (ELISA) tests on dogs across Europe to identify distribution and seropositivity in animals tested for selected CVBDs (Anaplasma spp., Ehrlichia spp., Borrelia burgdorferi, Leishmania spp., and Dirofilaria immitis) from 2016 through 2020. Geographic distribution of positive tests and relative percent positive values were mapped by the Nomenclature of Territorial Units for Statistics classification for regions with sufficient test results for reporting.

RESULTS

A total of 404,617 samples corresponding to 1,134,648 canine results were available from dogs tested in 35 countries over the 5-year study period. Over this period the number of test results per year increased whereas test positivity decreased. Leishmania spp. had the largest increase in total test results from 25,000 results in 2016 to over 60,000 results in 2020. Test positivity for Leishmania spp. fell from 13.9% in 2016 to 9.4% in 2020. Test positivity fell for Anaplasma spp. (7.3 to 5.3%), Ehrlichia spp. (4.3 to 3.4%), and Borrelia burgdorferi (3.3 to 2.4%). Dirofilaria immitis test positivity trended down with a high of 2.7% in 2016 and low of 1.8% in 2018. Leishmania spp. test positivity was highest in endemic areas and in several non-endemic countries with low numbers of test results. Co-positivity rates were significantly higher than expected for all pathogen test positive pairs except for Ehrlichia spp. with Borrelia burgdorferi and D. immitis with Borrelia burgdorferi.

CONCLUSIONS

This study represents the largest data set on CVBD seropositivity in Europe to date. The increase in the number of test results and decreasing test positivity over the study period may reflect changes in testing behavior and increased screening of healthy animals. The Europe-wide mapping of CVBD provides expected test positivity that can help inform veterinarians' decisions on screening and improve prevention and identification of these important, sometimes zoonotic, diseases.

Distribution of Phlebotomine Sand Flies (Diptera: Psychodidae) in the Lombardy Region, Northern Italy

Simple Summary

Pathogens transmitted to humans and animals by Phlebotomines are relatively neglected, as they cause infectious diseases which represent an underestimated burden in most European countries. Several sand fly species are competent vectors of Leishmaniasis, an endemic disease that has spread widely throughout the Mediterranean region in conjunction with sand flies’ movements. In the Lombardy region, information on sand flies is poor and/or outdated. Therefore, the present study was undertaken to preliminarily ascertain the species composition, distribution, and diversity in representative Lombardy localities. The sampling took advantage of regional surveillance plans namely, West Nile virus and leishmaniasis monitoring plans. A focused sampling was also performed in areas identified as favorable for vector presence. Sampling was conducted using CO₂–CDC traps conducted every two and/or three weeks. From trapping for the West Nile monitoring plan, 21 out of 44 capture sites were positive for sand flies, while for the leishmaniasis monitoring plan, 11 out of the 40 trapping sites detected sand flies’ presence. Specimen identification was conducted by identifying morphological features. Phlebotomus perniciosus was the most abundant species (87.76% of specimens collected). Adequate and well-structured monitoring of sand fly populations is essential to provide information about distribution patterns of vector species present in defined geographical areas, as they could enhance pathogen circulation.

Abstract

This study investigated the species composition and density of sand flies in the Lombardy region (Northern Italy). Sand flies were collected using CDC traps baited with CO₂ (CO₂–CDC traps) between June and August 2021. A total of 670 sand flies were collected. The specimens were identified as seven species belonging to two genera, Phlebotomus and Sergentomyia, namely, S. minuta, Ph. perniciosus, Ph. perfiliewii, Ph. neglectus, Ph. mascitti, Ph. papatasi, and Ph. ariasi. Phlebotomus perniciosus was the most abundant species (87.76%), followed by Ph. perfiliewii (7.31%), Ph. neglectus (3.13%), S. minuta (0.75%), Ph. mascitti (0.6%), Ph. papatasi (0.3%), and Ph. ariasi, for which only one specimen was identified. Among these identified species, five are considered vectors of Leishmania, which causes cutaneous and visceral leishmaniasis. As vector presence increases the risk of vector-borne leishmaniasis, these results suggest that Northern Italy could be a potential area of pathogen circulation over the next few years. These preliminary results suggest that the risk of borne leishmaniasis is high in this region of Northern Italy. Monitoring the distribution of sand fly species in areas suitable for their persistence is important for control programs aimed at reducing the risk of leishmaniasis infection.

Monitoring and detection of new endemic foci of canine leishmaniosis in northern continental Italy: An update from a study involving five regions (2018-2019)

Canine leishmaniosis (CanL) is an emerging zoonosis caused by Leishmania infantum and transmitted in southern Europe by phlebotomine sand flies of the subgenus Phlebotomus (Larroussius). Endemic foci of CanL have been recorded in northern continental Italy since early 1990s and attributed to the northward expansion of vector populations due to climatic changes in association with travelling/relocated infected dogs from the southern Mediterranean littoral. In this study, further spread of endemic Leishmania foci was monitored during 2018-2019 in five regions (Aosta Valley, Piedmont, Lombardy, Veneto and Friuli-Venezia Giulia), with focus to territories where investigations were not performed, or they have been inconclusive. Clinical cases of CanL identified by local veterinary practitioners and confirmed by reference diagnosis centers were regarded as autochthonous if their origin from, or travel to, areas endemic for CanL were excluded in the previous ≥2 years. Around these index cases, i) serosurveys for L infantum were carried out where indicated, ii) sampling from potential autochthonous cases in healthy or clinically-suspected resident dogs was intensified by collaborating veterinary practitioners, and iii) suitable sites were investigated for the presence of competent phlebotomine vectors. Fifty-seven municipalities whose enzootic status of CanL was unreported before 2018, were identified as endemic. The stability of 27 foci recorded over the past decade, was also confirmed. Competent phlebotomine vectors, mainly Phlebotomus perniciosus, were collected for the first time in 23 municipalities. The newly recorded endemic municipalities appear to be distributed over a west-to-east decreasing gradient: 30 in Piedmont, 21 in Lombardy, 4 in Veneto and 2 in Friuli-Venezia Giulia. As regards Veneto, it should be noted that a relatively restricted territory was investigated as several municipalities of the region had already been surveyed and detected as endemic for CanL in the past. Cold climate conditions of the easternmost region of Friuli-Venezia Giulia bordering non-endemic territories of Slovenia, are probably less favorable to L infantum transmission.

Toscana virus encephalitis in Southwest Germany: a retrospective study

Background

Toscana virus (TOSV) is an arthropod-borne virus transmitted by phlebotomine sandflies (Phlebotomus sp.) widespread throughout the Mediterranean having the potential to cause meningoencephalitis in humans. In Germany, the vectors of TOSV are introduced recently and become endemic especially in Southwestern Germany. As TOSV is not investigated regularly in patients with meningoencephalitis, cases of TOSV-neuroinvasive disease may remain mostly undetected.

Methods

We conducted a retrospective cohort study on patients with meningoencephalitis without identification of a causal pathogen from 2006 to 2016. Serologic assessment for anti-TOSV-IgG and IgM was performed on serum and CSF. Demographic, clinical and CSF data from TOSV-positive patients were compared to a cohort of patients with meningoencephalitis due to enterovirus. Informed consent was obtained from all included patients.

Results

We found 138 patients with meningoencephalitis without identified causal pathogen. From 98 of these patients CSF and serum was available for further testing. Additionally, we included 27 patients with meningoencephalitis due to enterovirus. We identified two patients with serological confirmed TOSV-neuroinvasive disease (TOSV-IgM and IgG positive, 2%) and two patients with possible TOSV-neuroinvasive disease (isolated TOSV-IgM positive, 2%). Overall, TOSV-neuroinvasive was detected in 4% of our cases with suspected viral meningoencephalitis. None of them had a history of recent travel to an endemic area.

Conclusions

We found cases of TOSV-neuroinvasive disease in our German cohort of patients with meningoencephalitis. As no recent history of travel to an endemic area was reported, it remains probable that these cases resemble autochthonous infections, albeit we cannot draw conclusions regarding the origin of the respective vectors. TOSV could be considered in patients with meningoencephalitis in Germany.

Phlebotomine sand fly survey in the Republic of Moldova: species composition, distribution and host preferences

BACKGROUND

Phlebotomine sand flies (Diptera: Psychodiae) in the Republic of Moldova have been understudied for decades. Our study provides a first update on their occurrence, species composition and bloodmeal sources after 50 years.

METHODS

During 5 seasons (2013-2017), 58 localities from 20 regions were surveyed for presence of sand flies using CDC light traps and manual aspirators. Species identification was done by a combination of morphological and molecular approaches (DNA barcoding, MALDI-TOF MS protein profiling). In engorged females, host blood was identified by three molecular techniques (RFLP, cytb sequencing and MALDI-TOF peptide mass mapping). Population structure of most abundant species was studied by cox1 haplotyping; phylogenetic analyses of ITS2 and cox1 genetic markers were used to resolve relationships of other detected species.

RESULTS

In total, 793 sand flies were collected at 30 (51.7%) localities from 12 regions of Moldova. Three species were identified by an integrative morphological and molecular approach: Phlebotomus papatasi, P. perfiliewi and Phlebotomus sp. (Adlerius), the first being the most abundant and widespread, markedly anthropophilic based on bloodmeal analyses, occurring also indoors and showing low population structure with only five haplotypes of cox1 detected. Distinct morphological and molecular characters of Phlebotomus sp. (Adlerius) specimens suggest the presence of a yet undescribed species.

CONCLUSIONS

Our study revealed the presence of stable sand fly populations of three species in Moldova that represent a biting nuisance as well as a potential threat of pathogen transmission and shall be further studied.

Vulnerabilities to and the Socioeconomic and Psychosocial Impacts of the Leishmaniases: A Review

The leishmaniases are a group of four vector-borne neglected tropical diseases (NTDs) with 1.6 billion people in some 100 countries at risk. They occur in certain eco-epidemiological foci that reflect manipulation by human activities, such as migration, urbanization and deforestation, of which poverty, conflict and climate change are key drivers. Given their synergistic impacts, risk factors and the vulnerabilities of poor populations and the launch of a new 2030 roadmap for NTDs in the context of the global sustainability agenda, it is warranted to update the state of knowledge of the leishmaniases and their effects. Using existing literature, we review socioeconomic and psychosocial impacts of leishmaniasis within a framework of risk factors and vulnerabilities to help inform policy interventions. Studies show that poverty is an overarching primary risk factor. Low-income status fosters inadequate housing, malnutrition and lack of sanitation, which create and exacerbate complexities in access to care and treatment outcomes as well as education and awareness. The co-occurrence of the leishmaniases with malnutrition and HIV infection further complicate diagnosis and treatment, leading to poor diagnostic outcomes and therapeutic response. Even with free treatment, households may suffer catastrophic health expenditure from direct and indirect medical costs, which compounds existing financial strain in low-income communities for households and healthcare systems. The dermatological presentations of the leishmaniases may result in long-term severe disfigurement, leading to stigmatization, reduced quality of life, discrimination and mental health issues. A substantial amount of recent literature points to the vulnerability pathways and burden of leishmaniasis on women, in particular, who disproportionately suffer from these impacts. These emerging foci demonstrate a need for continued international efforts to address key risk factors and population vulnerabilities if leishmaniasis control, and ultimately elimination, is to be achieved by 2030.

Canine Leishmaniasis Prevalence in the Slovenian Dog Population

Introduction

Leishmaniasis is a life-threatening zoonosis of which dogs are the major reservoir and sandflies are the vectors. Until now, the prevalence of canine leishmaniasis (CanL) in the Slovenian dog population was unknown.

Material and Methods

Epidemiological data, eye swabs and blood samples were taken from 465 dogs born in Slovenia and older than one year. Commercial ELISA kits and real-time PCR were used. For ELISA-positive samples, an immunofluorescence antibody test (IFAT) was performed. Descriptive statistics were used to characterise the samples. The one-sample nonparametric chi-square test was used to test whether the categories of a variable were equally distributed.

Results

A 59.9% proportion of the recruited dogs had travelled to endemic regions and 62.1% of them had not been protected by insect repellents. Skin symptoms that might be CanL-related were described in 109 of the dogs’ histories (23.4%), inappetence and/or weight loss in 25 (5.4%), and anaemia, intermittent fever, and/or lymphadenopathy in 19 (4.1%). At the time of recruitment, all dogs were asymptomatic. All samples were PCR negative, nine (1.9%) were ELISA positive, but none were IFAT positive. Five of the nine ELISA-positive dogs were non-travellers.

Conclusion

We conclude that the seroprevalence of canine leishmaniasis of 1.9 % in the autochthonous Slovenian dog population may pose a risk of endemic spread of the disease.

Ecology, seasonality and host preferences of Austrian Phlebotomus (Transphlebotomus) mascittii Grassi, 1908, populations

Background

Sand flies are principal vectors of the protozoan parasites Leishmania spp. and are widely distributed in all warmer regions of the world, including the Mediterranean parts of Europe. In Central European countries, the sand fly fauna is still under investigation. Phlebotomus mascittii, a suspected but unproven vector of Leishmania infantum, is regarded as the most widely distributed species in Europe. However, many aspects of its biology and ecology remain poorly known. The aim of this study was to provide new data on the biology and ecology of Ph. mascittii in Austria to better understand its current distribution and potential dispersal.

Methods

Sand flies were collected by CDC light traps at four localities in Austria for 11 (2018) and 15 weeks (2019) during the active sand fly season. Climatic parameters (temperature, relative humidity, barometric pressure and wind speed) were retrospectively obtained for the trapping periods. Sand flies were identified by a combined approach (morphology, DNA barcoding, MALDI-TOF protein profiling), and blood meals of engorged females were analysed by DNA sequencing and MALDI-TOF mass spectrometry.

Results

In total, 450 individuals of Ph. mascittii were caught. Activity was observed to start at the beginning of June and end at the end of August with peaks in mid-July at three locations and early August at one location. Increased activity was associated with relatively high temperatures and humidity. Also, more individuals were caught on nights with low barometric pressure. Analysis of five identified blood meals revealed chicken (Gallus gallus) and equine (Equus spp.) hosts. Sand fly abundance was generally associated with availability of hosts.

Conclusion

This study reports unexpectedly high numbers of Ph. mascittii at selected Austrian localities and provides the first detailed analysis of its ecology to date. Temperature and humidity were shown to be good predictors for sand fly activity. Blood meal analyses support the assumption that Ph. mascittii feeds on mammals as well as birds. The study significantly contributes to understanding the ecology of this sand fly species in Central Europe and facilitates prospective entomological surveys.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04787-2.

Leishmaniasis Beyond East Africa

Climate change is having a substantial impact on our environment and ecosystems and has altered the way humans live, access, and utilize resources with increased risk of zoonotic infectious disease encounters. As global temperatures continue to increase, they impact on public health, migration, food security and land conflict, and as new environments become favorable, exposure to disease carrying vectors. Increased forests or natural habitat clearance for land repurposing, urbanization, road building, and water management are related to an increase in emerging vector borne parasitic diseases. The East African region remains one of the most impacted regions globally for leishmaniasis, a vector borne disease that impacts significantly on the health, wellbeing and livelihoods of affected communities and for which a lack of reporting and control interventions hinder progress toward elimination of this neglected tropical disease. As our world continues to transform, both politically and climatically, it is essential that measures are put in place to improve surveillance and disease management with implementation of control measures, including vector control, especially in low- and middle-income countries that are expected to be most impacted by changes in climate. Only through effective management, now, can we be sufficiently resilient to preventing the inevitable spread of vectors into suitable habitat and expansion of the geographical range of leishmaniasis. This review offers a current perspective on Leishmaniasis as an endemic disease in East Africa and examines the potential of the recent emergence of Leishmania infection in hitherto unaffected regions to become a public health concern if no disease management is achieved.

Taxonomic Changes for Human and Animal Viruses, 2018 to 2020

The classification of viruses is relevant to a number of scientific and clinical disciplines, including the practice of diagnostic virology. Here, we provide an update to our previous review of taxonomic changes for disease-causing viruses in humans and vertebrate animals, covering changes between 2018 and 2020. Recent advances in virus taxonomy structure by the International Committee on Taxonomy of Viruses inform this update.

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

Integrative Approach to Phlebotomus mascittii Grassi, 1908: First Record in Vienna with New Morphological and Molecular Insights

Sand flies (Diptera: Psychodidae: Phlebotominae) are blood-feeding insects that transmit the protozoan parasites Leishmania spp. and various arthropod-borne (arbo) viruses. While in Mediterranean parts of Europe the sand fly fauna is diverse, in Central European countries including Austria mainly Phlebotomus mascittii is found, an assumed but unproven vector of Leishmania infantum. To update the currently understudied sand fly distribution in Austria, a sand fly survey was performed and other entomological catches were screened for sand flies. Seven new trapping locations of Ph. mascittii are reported including the first record in Vienna, representing also one of the first findings of this species in a city. Morphological identification, supported by fluorescence microscopy, was confirmed by two molecular approaches, including sequencing and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) protein profiling. Sand fly occurrence and activity were evaluated based on surveyed locations, habitat requirements and climatic parameters. Moreover, a first comparison of European Ph. mascittii populations was made by two marker genes, cytochrome c oxidase subunit 1 (COI), and cytochrome b (cytb), as well as MALDI-TOF mass spectra. Our study provides new important records of Ph. mascittii in Austria and valuable data for prospective entomological surveys. MALDI-TOF MS protein profiling was shown to be a reliable tool for differentiation between sand fly species. Rising temperatures and globalization demand for regular entomological surveys to monitor changes in species distribution and composition. This is also important with respect to the possible vector competence of Ph. mascittii.