scholarly journals Leishmaniasis in Eurasia and Africa: geographical distribution of vector species and pathogens

2019 ◽  
Vol 6 (5) ◽  
pp. 190334 ◽  
Author(s):  
Sarah Cunze ◽  
Judith Kochmann ◽  
Lisa K. Koch ◽  
Korbinian J. Q. Hasselmann ◽  
Sven Klimpel
Keyword(s):  
Vector Competence ◽  
Risk Assessments ◽  
Neglected Diseases ◽  
Vector Species ◽  
Niche Modelling ◽  
Northern Latitudes ◽  
Suitability Maps ◽  
Vector Borne ◽  
Pathogen Vector ◽  
Modelling Approach

Leishmaniasis is a vector-borne disease with a broad global occurrence and an increasing number of recorded cases; however, it is still one of the world's most neglected diseases. We here provide climatic suitability maps generated by means of an ecological niche modelling approach for 32 Phlebotomus vector species with proven or suspected vector competence for five Leishmania pathogens occurring in Eurasia and Africa. A GIS-based spatial overlay analysis was then used to compare the distributional patterns of vectors and pathogens to help evaluate the vector species–pathogen relationship currently found in the literature. Based on this single factor of vector incrimination, that is, co-occurrence of both vector and pathogen, most of the pathogens occurred with at least one of the associated vector species. In the case of L. donovani , only a not yet confirmed vector species, P. rodhaini, could explain the occurrence of the pathogen in regions of Africa. Phlebotomus alexandri and P. longiductus on the other hand, proven vector species of L. donovani, do not seem to qualify as vectors for the pathogen. Their distribution is restricted to northern latitudes and does not match the pathogen's distribution, which lies in southern latitudes. Other more locally confined mismatches were discussed for each pathogen species. The comparative geographical GIS-overlay of vector species and pathogens functions as a first indication that testing and re-evaluation of some pathogen–vector relationships might be worthwhile to improve risk assessments of leishmaniasis.

scholarly journals Wolbachia prevalence in the vector species Culex pipiens and Culex torrentium in a Sindbis virus-endemic region of Sweden

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Alexander Bergman ◽  
Jenny C. Hesson
Keyword(s):  
Culex Pipiens ◽  
Sindbis Virus ◽  
Vector Competence ◽  
Horizontal Transmission ◽  
Vector Species ◽  
Endemic Region ◽  
Species Determination ◽  
Terrestrial Arthropods ◽  
Endosymbiotic Bacteria ◽  
Vector Borne

Abstract Background Wolbachia pipientis are endosymbiotic bacteria present in a large proportion of terrestrial arthropods. The species is known to sometimes affect the ability of its host to transmit vector-borne pathogens. Central Sweden is endemic for Sindbis virus (SINV), where it is mainly transmitted by the vector species Culex pipiens and Culex torrentium, with the latter established as the main vector. In this study we investigated the Wolbachia prevalence in these two vector species in a region highly endemic for SINV. Methods Culex mosquitoes were collected using CDC light traps baited with carbon dioxide over 9 years at 50 collection sites across the River Dalälven floodplains in central Sweden. Mosquito genus was determined morphologically, while a molecular method was used for reliable species determination. The presence of Wolbachia was determined through PCR using general primers targeting the wsp gene and sequencing of selected samples. Results In total, 676 Cx. pipiens and 293 Cx. torrentium were tested for Wolbachia. The prevalence of Wolbachia in Cx. pipiens was 97% (95% CI 94.8–97.6%), while only 0.7% (95% CI 0.19–2.45%) in Cx. torrentium. The two Cx. torrentium mosquitoes that were infected with Wolbachia carried different types of the bacteria. Conclusions The main vector of SINV in the investigated endemic region, Cx. torrentium, was seldom infected with Wolbachia, while it was highly prevalent in the secondary vector, Cx. pipiens. The presence of Wolbachia could potentially have an impact on the vector competence of these two species. Furthermore, the detection of Wolbachia in Cx. torrentium could indicate horizontal transmission of the endosymbiont between arthropods of different species. Graphical abstract

scholarly journals Understanding the effect of temperature on Bluetongue disease risk in livestock

2019 ◽  
Author(s):  
Fadoua El Moustaid ◽  
Zorian Thronton ◽  
Hani Slamani ◽  
Sadie J. Ryan ◽  
Leah R. Johnson
Keyword(s):  
Disease Risk ◽  
Vector Competence ◽  
Basic Reproductive Number ◽  
Effect Of Temperature ◽  
Reproductive Number ◽  
Temperature Sensitive ◽  
Modeling Tools ◽  
Vector Borne Diseases ◽  
Thermal Range ◽  
Vector Borne

AbstractThe transmission of vector-borne diseases is governed by complex factors including pathogen characteristics, vector-host interactions, and environmental conditions. Temperature is a major driver for many vector-borne diseases including Bluetongue viral (BTV) disease, a midge-borne febrile disease of ruminants, notably livestock, whose etiology ranges from mild or asymptomatic to rapidly fatal, thus threatening animal agriculture and the economy of affected countries. Using modeling tools, we seek to predict where transmission can occur based on suitable temperatures for BTV. We fit thermal performance curves to temperature sensitive midge life history traits, using a Bayesian approach. Then, we incorporated these into a new formula for the disease basic reproductive number, R0, to include trait responses, for two species of key midge vectors, Culicoides sonorensis and Culicoides variipennis. Our results show that outbreaks of BTV are more likely between 15°C and 33°C with predicted peak transmission at 26°C. The greatest uncertainty in R0 is associated with the uncertainty in: mortality and fecundity of midges near optimal temperature for transmission; midges’ probability of becoming infectious post infection at the lower edge of the thermal range; and the biting rate together with vector competence at the higher edge of the thermal range. We compare our R0 to two other R0 formulations and show that incorporating thermal curves into all three leads to similar BTV risk predictions. To demonstrate the utility of this model approach, we created global suitability maps indicating the areas at high and long-term risk of BTV transmission, to assess risk, and anticipate potential locations of establishment.

scholarly journals Vector competence is strongly affected by a small deletion or point mutations in bluetongue virus

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
René G. P. van Gennip ◽  
Barbara S. Drolet ◽  
Paula Rozo Lopez ◽  
Ashley J. C. Roost ◽  
Jan Boonstra ◽  
...  
Keyword(s):  
Virus Replication ◽  
Bluetongue Virus ◽  
Vector Competence ◽  
Outer Shell ◽  
Virus Propagation ◽  
Virus Growth ◽  
Shell Protein ◽  
Vector Borne

Abstract Background Transmission of vector-borne virus by insects is a complex mechanism consisting of many different processes; viremia in the host, uptake, infection and dissemination in the vector, and delivery of virus during blood-feeding leading to infection of the susceptible host. Bluetongue virus (BTV) is the prototype vector-borne orbivirus (family Reoviridae). BTV serotypes 1–24 (typical BTVs) are transmitted by competent biting Culicoides midges and replicate in mammalian (BSR) and midge (KC) cells. Previously, we showed that genome segment 10 (S10) encoding NS3/NS3a protein is required for virus propagation in midges. BTV serotypes 25–27 (atypical BTVs) do not replicate in KC cells. Several distinct BTV26 genome segments cause this so-called ‘differential virus replication’ in vitro. Methods Virus strains were generated using reverse genetics and their growth was examined in vitro. The midge feeding model has been developed to study infection, replication and disseminations of virus in vivo. A laboratory colony of C. sonorensis, a known competent BTV vector, was fed or injected with BTV variants and propagation in the midge was examined using PCR testing. Crossing of the midgut infection barrier was examined by separate testing of midge heads and bodies. Results A 100 nl blood meal containing ±105.3 TCID50/ml of BTV11 which corresponds to ±20 TCID50 infected 50% of fully engorged midges, and is named one Midge Alimentary Infective Dose (MAID50). BTV11 with a small in-frame deletion in S10 infected blood-fed midge midguts but virus release from the midgut into the haemolymph was blocked. BTV11 with S1[VP1] of BTV26 could be adapted to virus growth in KC cells, and contained mutations subdivided into ‘corrections’ of the chimeric genome constellation and mutations associated with adaptation to KC cells. In particular one amino acid mutation in outer shell protein VP2 overcomes differential virus replication in vitro and in vivo. Conclusion Small changes in NS3/NS3a or in the outer shell protein VP2 strongly affect virus propagation in midges and thus vector competence. Therefore, spread of disease by competent Culicoides midges can strongly differ for very closely related viruses.

scholarly journals Vector Competence of Italian Populations of Culicoides for Some Bluetongue Virus Strains Responsible for Recent Northern African and European Outbreaks

Viruses ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 941 ◽  
Author(s):  
Valentina Federici ◽  
Maria Goffredo ◽  
Giuseppe Mancini ◽  
Michela Quaglia ◽  
Adriana Santilli ◽  
...  
Keyword(s):  
Bluetongue Virus ◽  
Vector Competence ◽  
Oral Infection ◽  
Balearic Islands ◽  
Rt Pcr ◽  
Vector Species ◽  
Vaccination Programs ◽  
Culicoides Obsoletus ◽  
Culicoides Imicola ◽  
Virus Strains

The distribution of Bluetongue virus (BTV) in Europe can be represented by two distinct and interconnected epidemiological systems (episystems), each characterized by different ecological characteristics and vector species. This study investigated the vector competence of Italian populations of Culicoides imicola and Culicoides obsoletus/scoticus to some representative BTV strains after artificial oral infection. The BTV strains were selected according to their ability to spread to one or both episystems and included BTV-4 ITA, responsible of the recent Italian and French BTV-4 outbreaks; the BTV-2 strain which caused the first BTV incursion in Italy, Corsica, and Balearic Islands; BTV-4 MOR, responsible for the epidemic in Morocco; and BTV-8, the strain which spread through Europe between 2006 and 2008. Blood-soaked cotton pledgets and Hemotek membrane feeder using Parafilm® membrane were used to artificially feed midges. For each population/strain, recovery rates (positive/tested heads) were evaluated using serogroup- and serotype-specific RT-PCR. The trial demonstrated that, except for the Abruzzo population of C. obsoletus/C. scoticus, which was refractory to BTV-4 MOR infection, all the investigated Culicoides populations are susceptible to the selected BTV strains and that, if prompt vaccination programs and restriction measures had not been implemented, BTV-2 and BTV-4 MOR could have spread all over Europe.

scholarly journals Evaluating the potential of ecological niche modelling as a component in marine non-indigenous species risk assessments

2015 ◽  
Vol 97 (1-2) ◽  
pp. 470-487 ◽  
Author(s):  
Sonja Leidenberger ◽  
Matthias Obst ◽  
Robert Kulawik ◽  
Kerstin Stelzer ◽  
Karin Heyer ◽  
...  
Keyword(s):  
Ecological Niche ◽  
Ecological Niche Modelling ◽  
Risk Assessments ◽  
Indigenous Species ◽  
Niche Modelling ◽  
Non Indigenous Species

scholarly journals Environmental Niche Modelling of Phlebotomine Sand Flies and Cutaneous Leishmaniasis Identifies Lutzomyia intermedia as the Main Vector Species in Southeastern Brazil

PLoS ONE ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. e0164580 ◽  
Author(s):  
Viviane Coutinho Meneguzzi ◽  
Claudiney Biral dos Santos ◽  
Gustavo Rocha Leite ◽  
Blima Fux ◽  
Aloísio Falqueto
Keyword(s):  
Cutaneous Leishmaniasis ◽  
Southeastern Brazil ◽  
Sand Flies ◽  
Environmental Niche ◽  
Vector Species ◽  
Niche Modelling ◽  
Phlebotomine Sand Flies

scholarly journals The seal louse (Echinophthirius horridus) in the Dutch Wadden Sea: investigation of vector-borne pathogens

2021 ◽  
Author(s):  
Jörg Hirzmann ◽  
David Ebmer ◽  
Guillermo J. Sánchez Contreras ◽  
Ana Rubio-García ◽  
Gerd Magdowski ◽  
...  
Keyword(s):  
Wadden Sea ◽  
Vector Competence ◽  
Pathogen Transmission ◽  
Grey Seal ◽  
Harbour Seals ◽  
Wide Range ◽  
Rehabilitation Period ◽  
Phocid Seals ◽  
Vector Borne

Abstract Background: Belonging to the anopluran family Echinophthiriidae, Echinophthirius horridus, the seal louse, has been reported to parasitize a broad range of representatives of phocid seals. So far, only few studies focused on vector function of echinophthiriid lice and knowledge on their role in pathogen transmission is still scarce. The current study aims to investigate the possible vector role of E. horridus parasitizing seals in the Dutch Wadden Sea.Methods: E. horridus seal lice were collected from 54 harbour seals (Phoca vitulina) and one grey seal (Halichoerus grypus) during their rehabilitation period at the Sealcentre Pieterburen, the Netherlands. DNA was extracted from pooled seal lice of individual seals for molecular detection of the seal heartworm Acanthocheilonema spirocauda, the rickettsial intracellular bacterium Anaplasma phagocytophilum, and the cell wall-less bacteria Mycoplasma spp. using PCR assays.Results: Seal lice from 35% of the harbour seals (19/54) and from the grey seal proved positive for A. spirocauda. The seal heartworm was molecularly characterised and phylogenetically analysed (rDNA, cox1). A nested PCR was developed for the cox1 gene to detect A. spirocauda stages in seal lice. A. phagocytophilum and a Mycoplasma species previously identified from a patient with disseminated ‘seal finger’ mycoplasmosis were detected the first time in seal lice. Conclusions: Our findings support the potential vector role of seal lice in transmission of A. spirocauda, and reveal new insights into the spectrum of pathogens occurring in seal lice. Studies on vector competence of E. horridus, especially for bacterial pathogens, are essentially needed in the future as these pathogens might have detrimental effects on the health of seal populations. Further, studies on the vector role of different echinophthiriid species infecting a wide range of pinniped hosts should be conducted to extend the knowledge of vector borne pathogens in seal lice.

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