Infection, dissemination, and transmission of lumpy skin disease virus in Aedes aegypti (Linnaeus), Culex tritaeniorhynchus (Giles), and Culex quinquefasciatus (Say) mosquitoes.

Lumpy skin disease virus (LSDV) is a transboundary viral disease in cattle and water buffaloes. Although this Poxvirus is supposedly transmitted by mechanical vectors, only a few studies have investigated the role of local vectors in the transmission of LSDV. This study examined the infection, dissemination, and transmission rates of LSDV in Aedes aegypti, Culex tritaeniorhynchus, and Culex quinquefasciatus following artificial membrane feeding of 102.7, 103.7, 104.7 TCID50/mL LSDV in sheep blood. The results demonstrated that these mosquito species were susceptible to LSDV, with Cx tritaeniorhynchus exhibiting significantly different characteristics from Ae. aegypti and Cx. quinquefasciatus. These three mosquito species were susceptible to LSDV. Ae. aegypti showed it as early as 2 days post-infection (dpi), indicating swift dissemination in this particular species. The extrinsic incubation period (EIP) of LSDV in Cx. tritaeniorhynchus and Cx. quinquefasciatus was 8 and 14 dpi, respectively. Ingestion of different viral titers in blood did not affect the infection, dissemination, or transmission rates of Cx. tritaeniorhynchus and Cx. quinquefasciatus. All rates remained consistently high at 8-14 dpi for Cx. tritaeniorhynchus. In all three species, LSDV remained detectable until 14 dpi. The present findings indicate that, Ae. aegypti, Cx. tritaeniorhynchus, and Cx. quinquefasciatus may act as vectors during the LSDV outbreak; their involvement may extend beyond being solely mechanical vectors.

Identification of the murine osteoblastic cell MC3T3-E1 as a permissive cell line in response to lumpy skin disease virus.

Lumpy skin disease virus (LSDV) is a rapidly emerging pathogen in China. Screening suitable cells for LSDV replication is vital for future research on pathogenic mechanisms and vaccine development. Previous comparative studies have identified that the rodent-derived BHK21 is a highly susceptible cell model to LSDV infection. Using western blot, indirect immune-fluorescence assay, flow cytometry, and transmission electron microscopy methods, this study is the first to identify the murine osteoblastic cell line MC3T3-E1 as a novel permissive cell model for LSDV infection. The establishment of MC3T3-E1 as a suitable infectious cell model enhances our understanding of the species range and cell types of the permissive cells and nonpermissive that support LSDV replication. It is helpful to accelerate future research on the pathogenesis, clinical application, and vaccine development of LSDV.

The immune response to lumpy skin disease virus in cattle is influenced by inoculation route.

Lumpy skin disease virus (LSDV) causes severe disease in cattle and water buffalo and is transmitted by hematophagous arthropod vectors. Detailed information of the adaptive and innate immune response to LSDV is limited, hampering the development of tools to control the disease. This study provides an in-depth analysis of the immune responses of calves experimentally inoculated with LSDV via either needle-inoculation or arthropod-inoculation using virus-positive Stomoxys calcitrans and Aedes aegypti vectors. Seven out of seventeen needle-inoculated calves (41%) developed clinical disease characterised by multifocal necrotic cutaneous nodules. In comparison 8/10 (80%) of the arthropod-inoculated calves developed clinical disease. A variable LSDV-specific IFN-γ immune response was detected in the needle-inoculated calves from 5 days post inoculation (dpi) onwards, with no difference between clinical calves (developed cutaneous lesions) and nonclinical calves (did not develop cutaneous lesions). In contrast a robust and uniform cell-mediated immune response was detected in all eight clinical arthropod-inoculated calves, with little response detected in the two nonclinical arthropod-inoculated calves. Neutralising antibodies against LSDV were detected in all inoculated cattle from 5-7 dpi. Comparison of the production of anti-LSDV IgM and IgG antibodies revealed no difference between clinical and nonclinical needle-inoculated calves, however a strong IgM response was evident in the nonclinical arthropod-inoculated calves but absent in the clinical arthropod-inoculated calves. This suggests that early IgM production is a correlate of protection in LSD. This study presents the first evidence of differences in the immune response between clinical and nonclinical cattle and highlights the importance of using a relevant transmission model when studying LSD.

The Acquisition and Retention of Lumpy Skin Disease Virus by Blood-Feeding Insects Is Influenced by the Source of Virus, the Insect Body Part, and the Time since Feeding.

Lumpy skin disease virus (LSDV) is a poxvirus that causes severe systemic disease in cattle and is spread by mechanical arthropod-borne transmission. This study quantified the acquisition and retention of LSDV by four species of Diptera (Stomoxys calcitrans, Aedes aegypti, Culex quinquefasciatus, and Culicoides nubeculosus) from cutaneous lesions, normal skin, and blood from a clinically affected animal. The acquisition and retention of LSDV by Ae. aegypti from an artificial membrane feeding system was also examined. Mathematical models of the data were generated to identify the parameters which influence insect acquisition and retention of LSDV. For all four insect species, the probability of acquiring LSDV was substantially greater when feeding on a lesion compared with feeding on normal skin or blood from a clinically affected animal. After feeding on a skin lesion LSDV was retained on the proboscis for a similar length of time (around 9 days) for all four species and for a shorter time in the rest of the body, ranging from 2.2 to 6.4 days. Acquisition and retention of LSDV by Ae. aegypti after feeding on an artificial membrane feeding system that contained a high titer of LSDV was comparable to feeding on a skin lesion on a clinically affected animal, supporting the use of this laboratory model as a replacement for some animal studies. This work reveals that the cutaneous lesions of LSD provide the high-titer source required for acquisition of the virus by insects, thereby enabling the mechanical vector-borne transmission. IMPORTANCE Lumpy skin disease virus (LSDV) is a high consequence pathogen of cattle that is rapidly expanding its geographical boundaries into new regions such as Europe and Asia. This expansion is promoted by the mechanical transmission of the virus via hematogenous arthropods. This study quantifies the acquisition and retention of LSDV by four species of blood-feeding insects and reveals that the cutaneous lesions of LSD provide the high titer virus source necessary for virus acquisition by the insects. An artificial membrane feeding system containing a high titer of LSDV was shown to be comparable to a skin lesion on a clinically affected animal when used as a virus source. This promotes the use of these laboratory-based systems as replacements for some animal studies. Overall, this work advances our understanding of the mechanical vector-borne transmission of LSDV and provides evidence to support the design of more effective disease control programmes.

Quantifying and Modeling the Acquisition and Retention of Lumpy Skin Disease Virus by Hematophagus Insects Reveals Clinically but Not Subclinically Affected Cattle Are Promoters of Viral Transmission and Key Targets for Control of Disease Outbreaks.

Lumpy skin disease virus (LSDV) is a vector-transmitted poxvirus that causes disease in cattle. Vector species involved in LSDV transmission and their ability to acquire and transmit the virus are poorly characterized. Using a highly representative bovine experimental model of lumpy skin disease, we fed four model vector species (Aedes aegypti, Culex quinquefasciatus, Stomoxys calcitrans, and Culicoides nubeculosus) on LSDV-inoculated cattle in order to examine their acquisition and retention of LSDV. Subclinical disease was a more common outcome than clinical disease in the inoculated cattle. Importantly, the probability of vectors acquiring LSDV from a subclinical animal (0.006) was very low compared with that from a clinical animal (0.23), meaning an insect feeding on a subclinical animal was 97% less likely to acquire LSDV than one feeding on a clinical animal. All four potential vector species studied acquired LSDV from the host at a similar rate, but Aedes aegypti and Stomoxys calcitrans retained the virus for a longer time, up to 8 days. There was no evidence of virus replication in the vector, consistent with mechanical rather than biological transmission. The parameters obtained in this study were combined with data from studies of LSDV transmission and vector life history parameters to determine the basic reproduction number of LSDV in cattle mediated by each of the model species. This reproduction number was highest for Stomoxys calcitrans (19.1), followed by C. nubeculosus (7.1) and Ae. aegypti (2.4), indicating that these three species are potentially efficient transmitters of LSDV; this information can be used to inform LSD control programs.IMPORTANCE Lumpy skin disease virus (LSDV) causes a severe systemic disease characterized by cutaneous nodules in cattle. LSDV is a rapidly emerging pathogen, having spread since 2012 into Europe and Russia and across Asia. The vector-borne nature of LSDV transmission is believed to have promoted this rapid geographic spread of the virus; however, a lack of quantitative evidence about LSDV transmission has hampered effective control of the disease during the current epidemic. Our research shows subclinical cattle play little part in virus transmission relative to clinical cattle and reveals a low probability of virus acquisition by insects at the preclinical stage. We have also calculated the reproductive number of different insect species, therefore identifying efficient transmitters of LSDV. This information is of utmost importance, as it will help to define epidemiological control measures during LSDV epidemics and of particular consequence in resource-poor regions where LSD vaccination may be less than adequate.

A lumpy skin disease virus which underwent a recombination event demonstrates more aggressive growth in primary cells and cattle than the classical field isolate.

Genomic changes by recombination have been recently observed in lumpy skin disease viruses circulating in Russia. The first characterized naturally occurring recombinant lumpy skin disease virus Saratov/2017 occurred through recombination between a live attenuated virus vaccine and the Southern African lumpy skin disease virus. Understanding if recombination can increase or decrease virulence of viruses through changes in different gene regions is required to improve the understanding of capripoxvirus biology. In this study, the in vitro and in vivo growth of the recombinant Saratov/2017 and the classical field isolate Dagestan/2015 was compared. Primary lamb kidney and lamb testis cells as well as the goat ovarian cell line were used to assess virus replication. In the goat ovarian cell line, Saratov/2017 and Dagestan/2015 induced comparable cytopathic activity and virus titres. In contrast, in primary lamb kidney and lamb testis cells, Saratov/2017 grew more aggressively causing more massive rounding up of cells, detachment and agglomeration compared to Dagestan/20152015. Growth curves of Saratov/2017 and Dagestan/2015 were assessed in primary lamb testis cells using different multiplicities of infection (MOI), with Saratov/2017 demonstrating faster replication at the different MOI and time points evaluated post-infection. In cattle, Saratov/2017 demonstrated more pronounced skin reactions when titrated by skin inoculation of serially diluted virus. In both primary cells and cattle, the titre of Saratov/2017 was significantly higher compared to Dagestan/2015 (p ≤ .05). These results demonstrate recombinant Saratov/2017 exhibits more aggressive replication properties.

Lumpy skin disease outbreaks in China, since 3 August 2019.

Lumpy skin disease (LSD) is a viral disease of cattle caused by LSD virus (LSDV). This disease poses a significant threat to stockbreeding and is listed as one of bovine notifiable diseases by OIE. Before 2019, LSD has not been reported in China. The first LSD outbreak was determined in China on August 3, 2019. Since then, a total of 7 LSD outbreaks have been reported in other 6 provinces in China, infecting 91 and killing 7 cattle. As of now, LSDV was detected in western and eastern China and also in Taiwan Island outside Mainland China. LSD is undoubtedly an emerging threat to the cattle industry in China.

A review: Lumpy skin disease and its emergence in India.

Lumpy skin disease (LSD) is a viral disease caused by lumpy skin disease virus (LSDV), a member of Capripoxvirus genus of Poxviridae family. It is a transboundary disease of the economic importance affecting cattle and water buffaloes. The disease is transmitted by arthropod vectors and causes high morbidity and low mortality. LSD has recently been reported first time in India with 7.1% morbidity among cattle. Generally, fever, anorexia, and characteristic nodules on the skin mucous membrane of mouth, nostrils, udder, genital, rectum, drop in milk production, abortion, infertility and sometimes death are the clinical manifestations of the disease. The disease is endemic in African and Middle East countries but has started spreading to Asian and other countries. It has been recently reported from China and Bangladesh sharing borders with India. We have summarized occurrence of LSD outbreaks in last 10 years in Asian countries for the first time. In India, currently epidemiological status of the disease is unknown. Vaccination along with strict quarantine measures and vector control could be effective for preventing the spread of the disease. This review aims to summarise the latest developments in the epidemiology with the focus on transboundary spread, aetiology and transmission, clinical presentations, diagnostics and management of the disease.

Minimum Infective Dose of a Lumpy Skin Disease Virus Field Strain from North Macedonia.

Infection with Lumpy Skin Disease virus (LSDV), as well as infections with other Capripox virus species, are described as the most severe pox diseases of production animals and are therefore listed as notifiable diseases under the guidelines of the World Organization for Animal Health (OIE). To our knowledge there is only a single study examining dose dependency, clinical course, viremia, virus shedding, as well as serological response following experimental LSDV "Neethling" inoculation. Here, we inoculated cattle with four different doses of LSDV strain "Macedonia2016", a recently characterized virulent LSDV field strain, and examined clinical symptoms, viremia, viral shedding, and seroconversion. Interestingly, around 400 cell culture infectious dose50 (CCID50) of LSDV-"Macedonia2016" were sufficient to induce generalized Lumpy Skin Disease (LSD) in two out of six cattle but with a different incubation time, whereas the other animals of this group showed only a mild course of LSD. However, differences in incubation time, viral loads, serology, and in the clinical scoring could not be observed in the other three groups. In summary, we concluded that experimental LSDV infection of cattle with an infectious virus titer of 105 to 106 CCID50/mL of "Macedonia2016" provides a robust and sufficient challenge model for future studies.

Madin-Darby bovine kidney (MDBK) cells are a suitable cell line for the propagation and study of the bovine poxvirus lumpy skin disease virus.

Lumpy skin disease virus (LSDV) is a poxvirus that causes systemic disease in cattle, resulting in substantial economic loss to affected communities. LSDV is a rapidly emerging pathogen of growing global concern that recently spread from Africa and the Middle East into Europe and Asia, impacting the cattle population in these regions. An increase in research efforts into LSDV is required to address key knowledge gaps, however this is hampered by lack of suitable cell lines on which to propagate and study the virus. In this work we describe the replication and spread of LSDV on Madin-Darby bovine kidney (MDBK) cells, and the formation of foci-type poxvirus plaques by LSDV on MDBK cells. Methods utilising MDBK cells to quantify neutralising antibodies to LSDV, and to purify LSDV genomic DNA suitable for short read sequencing are described. These research methods broaden the tools available for LSDV researchers and will facilitate the gathering of evidence to underpin the development of LSD control and prevention programmes.

Lumpy skin disease (LSD) outbreaks in cattle in Odisha state, India in August 2019: Epidemiological features and molecular studies.

Lumpy skin disease (LSD) caused by lumpy skin disease virus (LSDV) inflicts significant economic losses in cattle production with impact on livelihoods of smallholders. This study reports the first occurrence of LSD in cattle in India and analyses epidemiological and genetic characterization data from LSD outbreaks in five districts of Odisha state in August 2019. In all, 182 of 2,539 cattle were affected with an apparent morbidity rate of 7.1% and no mortality. Out of 102 samples from 60 LSD suspected and 17 asymptomatic in-contact cattle tested, 29.87% cattle were positive by capripoxvirus generic PCR and 37.66% were positive by LSDV real-time PCR. All the in-contact cattle tested were negative for LSDV. Among affected cattle, LSDV genome was detected more in scabs (79.16%) than blood (31.81%) and frozen bull semen (20.45%). Differential diagnosis by PCR was negative for pseudo-LSD, buffalopox, cowpox, pseudo-cowpox and bovine papular stomatitis. Five selected PCR and real-time PCR-positive LSDV DNA were sequenced in three genomic regions, P32 (LSDV074), F (LSDV117) and RPO30 (LSDV036). Phylogenetic analysis based on partial P32 and F gene sequences and complete RPO30 gene sequences showed that all the five Indian LSDV strains were identical and clustered with other field strains of LSDV circulating globally. However, the F and RPO30 gene sequence analyses revealed that Indian LSDV strains are genetically closer to the South African NI2490/KSGP-like strains than the strains detected in Europe, which was rather surprising. The present study established the existence of LSDV in India and involvement of LSDV field strains in the outbreaks. Additionally, we provided evidence of LSDV shedding in semen of naturally infected bulls. Further studies are required to determine the source of LSD introduction, extent of spread, modes of transmission and impact on dairy cattle production in India and effective control measures must be undertaken urgently.

Modeling the lumpy skin disease risk probability in central Zagros Mountains of Iran.

BACKGROUND: New Lumpy Skin Disease (LSD) outbreaks are currently circulating in Chaharmahal and Bakhtiari province, (western Iran, in central Zagros Mountains). OBJECTIVES: The aim of this study was to model the risk probability of LSD in this area. METHOD: Data were collected from veterinary organizations between 2012 and 2016. During this period, 290 outbreaks were registered. The herds were grazing and zero grazing. The average size of herds was 2958. We analyzed the potential for an outbreak of LSD in this area basing on the grid maps with the resolution of 1 km. In this study, 22 environmental variables (19 bioclimatic and 3 topography variables) were used to explore the environmental influences on LSD outbreak by maximum entropy ecological niche modeling (MaxEnt). RESULTS: The results showed that mainly the central, northern, northeast and southern parts of Charmahal and Bakhtiari were the most very high risk areas for LSD. The MaxEnt model performed, with an area under the receiver operating characteristic curve (AUC) of 0.977 and 0.972 for training and test data, respectively. It showed high accuracy for predicting the prevalence of LSD (AUC close to 1). The precipitation of coldest season, isothermality and mean temperature of wettest season made the greatest contribution to the model (68.1%). Evaluating the importance of environmental variables, which were derived from the jackknife test, stated the precipitation of the wettest period and the coldest season and isothermality as the bioclimatic variables in explaining LSD prevalence compared to the other variables. CONCLUSION: The MaxEnt model could be applied to predict the LSD risk probability of occurrence in central Zagros Mountains of Iran based on the current prevalence data of the disease. Also, the model confirmed that coexistence of weather conditions including defined humidity and temperature is necessary for the disease occurrence.

Field observations and experiences gained from the implementation of control measures against lumpy skin disease in South-East Europe between 2015 and 2017.

The first epidemics of lumpy skin disease (LSD) reported in Europe in 2015 severely affected the cattle farming sector in several Balkan countries. After the first incursion into Greece in 2015, the disease quickly spread across the Balkan region with over 7000 outbreaks reported by the end of 2016. Thanks to a coordinated regional control and eradication policy, the spread of the disease was halted by the end of 2017. Regional large-scale vaccination campaign with effective homologous vaccines and high vaccination coverage revealed to be essential for the successful control the disease, supported by other measures such as early detection of outbreaks, total or partial stamping out and restrictions on cattle movements. The aim of this paper is to discuss the field observations, challenges and lessons learnt while dealing with the first LSD epidemics in Europe. The cross-border collaboration by the veterinary authorities of all affected countries, coordinated by the European Commission and the technical support provided by many other international organizations played a fundamental role in stopping the spread of a disease that otherwise could have expanded further to the European territory causing a large damage to the whole European cattle farming industry. The experience obtained during the control of LSD epidemics indicates that in the future LSD spread can be effectively halted, provided that appropriate surveillance plans and vigilance remains in place in the areas at risk of re-incursion, especially those bordering endemic countries.

Inferences about the transmission of lumpy skin disease virus between herds from outbreaks in Albania in 2016.

Lumpy skin disease has recently emerged as a major threat to cattle populations outside of Africa, where it is endemic. In 2015 the first ever European outbreaks occurred in Greece, which were followed by spread across much of the Balkans in 2016. Here we use a simple mathematical model for the transmission of lumpy skin disease virus (LSDV) between herds to explore factors influencing its spread by fitting it to data on outbreaks in Albania in 2016. We show that most transmission occurs over short distances (<5 km), but with an appreciable probability of transmission at longer distances. We also show that there is evidence for seasonal variation in the force of infection associated with temperature, possibly through its influence on the relative abundance of the stable fly, Stomoxys calcitrans. These two results together are consistent with LSDV being transmitted by the bites of blood-feeding insects, though further work is required to incriminate specific species as vectors. Finally, we show that vaccination has a significant impact on spread and estimate the vaccine effectiveness to be 76%.

Transmission of lumpy skin disease virus: A short review.

Lumpy skin disease (LSD) is a viral transboundary disease endemic throughout Africa and of high economic importance that affects cattle and domestic water buffaloes. Since 2012, the disease has spread rapidly and widely throughout the Middle Eastern and Balkan regions, southern Caucasus and parts of the Russian Federation. Before vaccination campaigns took their full effect, the disease continued spreading from region to region, mainly showing seasonal patterns despite implementing control and eradication measures. The disease is capable of appearing several hundred kilometers away from initial (focal) outbreak sites within a short time period. These incursions have triggered a long-awaited renewed scientific interest in LSD resulting in the initiation of novel research into broad aspects of the disease, including epidemiology, modes of transmission and associated risk factors. Long-distance dispersal of LSDV seems to occur via the movement of infected animals, but distinct seasonal patterns indicate that arthropod-borne transmission is most likely responsible for the swift and aggressive short-distance spread of the disease. Elucidating the mechanisms of transmission of LSDV will enable the development of more targeted and effective actions for containment and eradication of the virus. The mode of vector-borne transmission of the disease is most likely mechanical, but there is no clear-cut evidence to confirm or disprove this assumption. To date, the most likely vectors for LSDV transmission are blood-sucking arthropods such as stable flies (Stomoxys calcitrans), mosquitoes (Aedes aegypti), and hard ticks (Rhipicephalus and Amblyomma species). New evidence suggests that the ubiquitous, synanthropic house fly, Musca domestica, may also play a role in LSDV transmission, but this has not yet been tested in a clinical setting. The aim of this review is to compile and discuss the earlier as well as the most recent research data on the transmission of LSDV.

Using the basic reproduction number to assess the risk of transmission of lumpy skin disease virus by biting insects.

In recent years, lumpy skin disease virus (LSDV) has emerged as a major threat to cattle outside Africa, where it is endemic. Although evidence suggests that LSDV is transmitted by the bites of blood sucking arthropods, few studies have assessed the risk of transmission posed by particular vector species. Here this risk is assessed by calculating the basic reproduction number (R0 ) for transmission of LSDV by five species of biting insect: the stable fly, Stomoxys calcitrans, the biting midge, Culicoides nubeculosus, and three mosquito species, Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Parameters relating to mechanical transmission of LSDV were estimated using new analyses of previously published data from transmission experiments, while vector life history parameters were derived from the published literature. Uncertainty and sensitivity analyses were used to compute R0 for each species and to identify those parameters which influence its magnitude. Results suggest that S. calcitrans is likely to be the most efficient at transmitting LSDV, with Ae. aegypti also an efficient vector. By contrast, C. nubeculosus, An. stephensi, and Cx. quinquefasciatus are likely to be inefficient vectors of LSDV. However, there is considerable uncertainty associated with the estimates of R0 , reflecting uncertainty in most of the constituent parameters. Sensitivity analysis suggests that future experimental work should focus on estimating the probability of transmission from insect to bovine and on the virus inactivation rate in insects.

Risk of introduction of Lumpy Skin Disease into France through imports of cattle.

The lumpy skin disease (LSD) virus belongs to the genus Capripoxvirus and causes a disease in cattle with economic impacts. In November 2014, the disease was first reported in Europe (in Cyprus); it was then reported in Greece (in August 2015) and has spread through different Balkan countries since 2016. Although vector transmission is predominant in at-risk areas, long-distance transmission usually occurs through movements of infected cattle. In order to estimate the threat for France, a quantitative import risk analysis (QIRA) model was developed to assess the risk of LSD being introduced into France by imports of cattle. Based on available information and using a stochastic model, the probability of a first outbreak of LSD in France following the import of batches of infected live cattle for breeding or fattening was estimated to be 5.4 × 10-4 (95% probability interval [PI]: 0.4 × 10-4 ; 28.7 × 10-4 ) in summer months (during high vector activity) and 1.8 × 10-4 (95% PI: 0.14 × 10-4 ; 15 × 10-4 ) in winter months. The development of a stochastic QIRA made it possible to quantify the risk of LSD being introduced into France through imports of live cattle. This tool is of prime importance because the LSD situation in the Balkans is continuously changing. Indeed, this model can be updated to process new information on the changing health situation in addition to new data from the TRAde Control and Expert System (TRACES, EU database). This model is easy to adapt to different countries and to other diseases.

Transmission dynamics of lumpy skin disease in Ethiopia.

Lumpy skin disease (LSD) is a severe disease of cattle caused by a Capripoxvirus and often caused epidemics in Ethiopia and many other countries. This study was undertaken to quantify the transmission between animals and to estimate the infection reproduction ratio in a predominantly mixed crop-livestock system and in intensive commercial herd types. The transmission parameters were based on a susceptible-infectious-recovered (SIR) epidemic model with environmental transmission and estimated using generalized linear models. The transmission parameters were estimated using a survival rate of infectious virus in the environment equal to 0·325 per day, a value based on the best-fitting statistical model. The transmission rate parameter between animals was 0·072 (95% CI 0·068-0·076) per day in the crop-livestock production system, whereas this transmission rate in intensive production system was 0·076 (95% CI 0·068-0·085) per day. The reproduction ratio (R) of LSD between animals in the crop-livestock production system was 1·07, whereas it was 1·09 between animals in the intensive production system. The calculated R provides a baseline against which various control options can be assessed for efficacy.

Epidemiological and Molecular Studies on Lumpy Skin Disease Outbreaks in Turkey during 2014-2015.

This study was carried out to explore epidemiological and molecular features of lumpy skin disease virus (LSDV) in the Aegean, Central Anatolian and Mediterranean regions of Turkey, to evaluate the risk factors associated with LSDV infection and to investigate the financial impact of LSD and potential role of the Culicoides spp. in the transmission of LSDV. Samples were obtained from 611 cattle, each from different farms, and each clinically suspected to be infected with LSDV during the months of July 2014 and June 2015. Culicoides spp. were trapped from April to June 2015. Genetic characterization of the local LSDV field isolates was conducted by sequencing G-protein-coupled chemokine receptor gene segment. Real-time PCR high-resolution melting analysis was used for distinguishing each type of capripoxviruses. Viral DNA was detected in 448 of the 611 animals and Culicoides midges. Three hundred and ninety-three of the 448 affected farms were surveyed. The morbidity and mortality rates detected were 12.3% and 6.4%, respectively. Phylogenetic analysis showed that the field isolates in this study were clustered together with other Africa and Middle East isolates. Genotyping of isolates from infected cattle has revealed the presence of LSDV. A generalized mixed linear model showed that there were positive associations between LSDV infection, European breeds, small-sized family-type farms and nearness of farm to a lake. The financial cost of disease presence in surveyed cattle farms was estimated to be 72.75 GBP per head. The sequence analysis of the mitochondrial cytochrome oxidase subunit I gene showed that the species of Culicoides in LSDV-positive pools was Culicoides punctatus. Detection of LSDV in Culicoides punctatus suggests that it may have played a role in transmitting LSDV. Furthermore, movement of infected animals into disease-free areas increases the risk of the transmission of LSD. Control strategies for LSDV infection should include consideration of the risk factors identified in this study.

High relative abundance of the stable fly Stomoxys calcitrans is associated with lumpy skin disease outbreaks in Israeli dairy farms.

The vector of lumpy skin disease (LSD), a viral disease affecting Bovidae, is currently unknown. To evaluate the possible vector of LSD virus (LSDV) under field conditions, a yearlong trapping of dipterans was conducted in dairy farms that had been affected by LSD, 1-2 years previously. This was done in order to calculate monthly relative abundances of each dipteran in each farm throughout the year. The relative abundances of Stomoxys calcitrans (Diptera: Muscidae) in the months parallel to the outbreaks (December and April) were significantly higher than those of other dipterans. A stable fly population model based on weather parameters for the affected area was used to validate these findings. Its results were significantly correlated with S. calcitrans abundance. This model, based on weather parameters during the epidemic years showed that S. calcitrans populations peaked in the months of LSD onset in the studied farms. These observations and model predictions revealed a lower abundance of stable flies during October and November, when LSD affected adjacent grazing beef herds. These findings therefore suggest that S. calcitrans is a potential vector of LSD in dairy farms and that another vector is probably involved in LSDV transmission in grazing herds. These findings should be followed up with vector competence studies.