Putative roles of mosquitoes (Culicidae) and biting midges (Culicoides spp.) as mechanical or biological vectors of lumpy skin disease virus.

The stable fly Stomoxys calcitrans (Diptera: Muscidae) is considered as the main mechanical vector of the lumpy skin disease virus (LSDV). In addition, the mosquito species Aedes aegypti (Diptera: Culicidae) was shown to transmit the virus from donor to receptor animals. Retention of the virus for several days was shown for two additional tropical mosquito species and the biting midge Culicoides nubeculosus (Diptera: Ceratopogonidae). In the present study, viral retention for 10- or 7-days post feeding on virus-spiked blood through a membrane was shown for field-collected Aedes japonicus and laboratory-reared Culex pipiens, two widely distributed mosquito species in temperate regions. Viral DNA could be detected from honey-coated Flinders Technology Associates (FTA) cards and shedded faeces for 1 or 4 days after an infectious blood meal was given to Ae. aegypti. Virus increase over time and virus dissemination was observed in laboratory-reared C. nubeculosus, but the virus could be isolated from field-collected biting midges only from the day of exposure to the blood meal. Thus, mosquitoes might serve as mechanical vectors of LSDV in case of interrupted feeding. A putative biological virus transmission by Culicoides biting midges, as suspected from field observations, deserves further investigations

Potential mechanical transmission of Lumpy skin disease virus (LSDV) by the stable fly (Stomoxys calcitrans) through regurgitation and defecation.

Lumpy skin disease (LSD) is a viral disorder of cattle caused by the lumpy skin disease virus (LSDV) which can induce severe infections leading to high economic losses. Being of African origin, the first LSD outbreaks in Europe occurred in Greece and later in the Balkan region. Little is known about the mode of transmission, especially in relation to the potential role of arthropods vectors. The purpose of our study was to investigate the role of Stomoxys calcitrans in the transmission of LSDV and their presence at different farms in Switzerland. Laboratory-reared flies were exposed to LSDV spiked-blood and incubated under a realistic fluctuating temperature regime. Body parts, regurgitated blood, and faecal samples were analysed by qPCR for the presence of viral DNA and infectious virus at different time points post-feeding (p.f.). LSDV DNA was detected in heads, bodies, and regurgitated blood up to three days p.f. and up to two days p.f. in the faeces. Infectious virus was isolated from bodies and faeces up to two days and in the regurgitated blood up to 12 h p.f. There was no increase in viral load, consolidating the role of S. calcitrans as mechanical vectors for LSDV. Stomoxys flies were present at all eight farms investigated, including a farm located at 2128 m asl. The persistence of LSDV in S. calcitrans in combination with the long flight ranges of this abundant and widespread fly might have implications on LSD epidemiology and on implementing control measures during disease outbreaks

Vector competence of Culicoides biting midges from Switzerland for African horse sickness virus and epizootic haemorrhagic disease virus

Culicoides biting midges unexpectedly arose in Europe as highly efficient vectors of bluetongue virus in the epidemics that started in the Netherlands in 2006. They are known vectors of other orbiviruses, such as African horse sickness (AHSV) and epizootic haemorrhagic disease viruses (EHDV), which are not endemic to Europe. We investigated whether Culicoides occurring in Switzerland at two altitudes (Swiss Plateau, 650 meters above sea level [masl]; and pre-alpine, 2,130 masl) can act as vectors for AHSV and EHDV (two strains each). Biting midges were collected from farms, allowed to feed on virus-spiked blood meals through an artificial membrane in the laboratory and incubated for eight days under two temperature regimes (22 ± 6 °C or 26 ± 6 °C) reflecting a summer day or a hot spell on the Swiss Plateau. Vector competence was assessed from head homogenates by RT-qPCR and virus isolation. Overall, over 15,000 biting midges were exposed to any one of the four viruses. Fully disseminated infections were identified for all four virus strains in 14 individuals (6 C. obsoletus, 8 C. scoticus, as identified by MALDI-TOF mass spectrometry), all originating from the Swiss Plateau, by RT-qPCR. Viable virus could be isolated from 8 of these specimens. Dissemination rates ranged from 1-5%. No viral dissemination was observed in biting midges from the high altitude, predominantly belonging to the species C. grisescens, which were only investigated at the high temperature regime. However, a multivariable logistic regression model revealed no statistical difference in the dissemination rates based on the origin of midges (altitude), virus strain or temperature regime. Thus, AHDV and EHDV transmission is feasible on the Swiss Plateau but unlikely in the pre-alpine area by considering vector abundance. Ways of potential virus introduction include illegal animal movement but also long-distance wind-dispersal of infectious Culicoides

Potential mechanical transmission of Lumpy skin disease virus (LSDV) by the stable fly (Stomoxys calcitrans) through regurgitation and defecation

Lumpy skin disease (LSD) is a viral disorder of cattle caused by the lumpy skin disease virus (LSDV) which can induce severe infections leading to high economic losses. Being of African origin, the first LSD outbreaks in Europe occurred in Greece and later in the Balkan region. Little is known about the mode of transmission, especially in relation to the potential role of arthropods vectors. The purpose of our study was to investigate the role of Stomoxys calcitrans in the transmission of LSDV and their presence at different farms in Switzerland. Laboratory-reared flies were exposed to LSDV spiked-blood and incubated under a realistic fluctuating temperature regime. Body parts, regurgitated blood, and faecal samples were analysed by qPCR for the presence of viral DNA and infectious virus at different time points post-feeding (p.f.). LSDV DNA was detected in heads, bodies, and regurgitated blood up to three days p.f. and up to two days p.f. in the faeces. Infectious virus was isolated from bodies and faeces up to two days and in the regurgitated blood up to 12 h p.f. There was no increase in viral load, consolidating the role of S. calcitrans as mechanical vectors for LSDV. Stomoxys flies were present at all eight farms investigated, including a farm located at 2128 m asl. The persistence of LSDV in S. calcitrans in combination with the long flight ranges of this abundant and widespread fly might have implications on LSD epidemiology and on implementing control measures during disease outbreaks

Associations of myosteatosis with disc degeneration: A 3T magnetic resonance imaging study in individuals with impaired glycaemia

Abstract Background Intervertebral disc degeneration (IVDD) may be linked to dysregulations of skeletal muscle glucose metabolism and fatty alterations of muscle composition (Myosteatosis). Our aim was to evaluate the different associations of magnetic resonance imaging (MRI)‐based paravertebral myosteatosis with lumbar disc degeneration in individuals with impaired glucose metabolism and normoglycaemic controls. Methods In total, 304 individuals (mean age: 56.3 ± 9.1 years, 53.6% male sex, mean body mass index [BMI]: 27.6 ± 4.7 kg/m2) from a population‐based cohort study who underwent 3‐Tesla whole‐body chemical‐shift‐encoded (six echo times) and T2‐weighted single‐shot‐fast‐spin‐echo MRI were included. Lumbar disc degeneration was assessed at motion segments L1 to L5, categorized according to the Pfirrmann score and defined as Pfirrmann grade > 2 and/or disc bulging/herniation on at least one segment. Fat content of the autochthonous back muscles and the quadratus lumborum muscle was quantified as proton density fat fraction (PDFFmuscle). Logistic regression models adjusted for age, sex, BMI and regular physical activity were calculated to evaluate the association between PDFFmuscle and outcome IVDD. Results The overall prevalence of IVDD was 79.6%. There was no significant difference in the prevalence or severity distribution of IVDD between participants with or without impaired glucose metabolism (77.7% vs. 80.7%, P = 0.63 and P = 0.71, respectively). PDFFmuscle was significantly and positively associated with an increased risk for the presence of IVDD in participants with impaired glycaemia when adjusted for age, sex and BMI (PDFFautochthonous back muscles: odds ratio [OR] 2.16, 95% confidence interval [CI] [1.09, 4.3], P = 0.03; PDFFquadratus lumborum: OR 2.01, 95% CI [1.04, 3.85], P = 0.04). After further adjustment for regular physical activity, the results attenuated, albeit approaching statistical significance (PDFFautochthonous back muscles: OR 1.97, 95% CI [0.97, 3.99], P = 0.06; PDFFquadratus lumborum: OR 1.86, 95% CI [0.92, 3.76], P = 0.09). No significant associations were shown in healthy controls (PDFFautochthonous back muscles: OR 0.62, 95% CI [0.34, 1.14], P = 0.13; PDFFquadratus lumborum: OR 1.06, 95% CI [0.6, 1.89], P = 0.83). Conclusions Paravertebral myosteatosis is positively associated with intervertebral disc disease in individuals with impaired glucose metabolism, independent of age, sex and BMI. Regular physical activity may confound these associations. Longitudinal studies will help to better understand the pathophysiological role of skeletal muscle in those with concomitant disturbed glucose haemostasis and intervertebral disc disease, as well as possible underlying causal relationships