Scientific Opinion on lumpy skin disease

Prevalence of lumpy skin disease and associated risk factors in beef cattle in Rembang Regency, Central Java, Indonesia

Background and Aim

Lumpy skin disease (LSD) is an economically devastating infectious disease in cattle. Rembang Regency, located in Central Java, Indonesia, has suffered over 3800 cases of LSD and 75 deaths since early 2023. This region holds the 4th number of most populous beef cattle producers in Central Java. However, until now, there have been no reports on the prevalence and risk factors related to LSD in beef cattle in Rembang Regency, Central Java, Indonesia. Therefore, this study aimed to estimate the prevalence of LSD and identify associated risk factors in Rembang Regency, Central Java, Indonesia.

Materials and Methods

The sample size was 458 cattle, which were determined using the formula (n = 4PQ/L2) and two-stage random sampling technique, were examined physically through LSD typical clinical signs, namely distinguishing firm, circumscribed, few (mild forms) to multiple (severe forms) skin nodules. Structured questionnaires and interviews with farm owners were used to identify risk factors. The data related to the LSD were analyzed using descriptive statistics, bivariate analysis with Chi-square and odd ratios, and multivariate logistic regression to retrieve the logit model. All data were compiled in Microsoft® Excel, while analyses were performed using SPSS version 26.0.

Results

The prevalence of LSD in Rembang Regency was 28.2%. There were 11 significant risk factors associated with LSD. The multivariate analysis indicated that risk factors significantly contributing to LSD were knowledge of LSD transmission (p = 0.035, Odds ratios [OR] = 2.933), waste management (p = 0.014, OR = 4.015), rainy season (p = 0.019, OR = 2.944), and proximity between farms (p = 0.003, OR = 4.506). The logistic regression model analysis was as follows: LSD (Y) = -6.719 + 1.041 (knowledge of LSD transmission) + 1.390 (waste management) + 1.080 (rainy season) + 1.505 (proximity between farms).

Conclusio

n: This study revealed a significant prevalence of LSD in Rembang Regency, Central Java, Indonesia, with 28.2% of cattle affected. Key risk factors contributing to LSD outbreaks were insufficient knowledge of transmission, inadequate waste management, seasonal rainfall, and close proximity between farms. These findings emphasize the need for targeted interventions, including educational programs for farm owners, improved waste management practices, and strategies to mitigate seasonal and spatial risks to control LSD in the region effectively.

A systematic review of epidemiological modelling in response to lumpy skin disease outbreaks

Lumpy skin disease (LSD) is an infectious disease currently spreading worldwide and poses a serious global threat. However, there is limited evidence and understanding to support the use of models to inform decision-making in LSD outbreak responses. This review aimed to identify modelling approaches that can be used before and during an outbreak of LSD, examining their characteristics and priorities, and proposing a structured workflow. We conducted a systematic review and identified 60 relevant publications on LSD outbreak modelling. The review identified six categories of question to be addressed following outbreak detection (origin, entry pathway, outbreak severity, risk factors, spread, and effectiveness of control measures), and five analytical techniques used to address them (descriptive epidemiology, risk factor analysis, spatiotemporal analysis, dynamic transmission modelling, and simulation modelling). We evaluated the questions each analytical technique can address, along with their data requirements and limitations, and accordingly assigned priorities to the modelling. Based on this, we propose a structured workflow for modelling during an LSD outbreak. Additionally, we emphasise the importance of pre-outbreak preparation and continuous updating of modelling post-outbreak for effective decision-making. This study also discusses the inherent limitations and uncertainties in the identified modelling approaches. To support this workflow, high-quality data must be collected in standardised formats, and efforts should be made to reduce inherent uncertainties of the models. The suggested modelling workflow can be used as a process to support rapid response for countries facing their first LSD occurrence and can be adapted to other transboundary diseases.

Evaluation of longitudinal passive immunity transfer against lumpy skin disease virus in calves by different serological methods

To implement effective lumpy skin disease (LSD) control measures, such as timely vaccination, particularly in calves and serological monitoring, it is necessary to evaluate immune response after vaccination, both in adult cattle and in their calves. The aim of this study was to evaluate passive immunity transfer and duration of maternal antibodies against lumpy skin disease virus (LSDV) in calves born to vaccinated cows by two different serological methods. The longitudinal study was carried out on two farms in Serbia where no cases were reported during LSD outbreak in 2016. Fifteen cows on each farm were vaccinated and revaccinated with attenuated vaccine - Neethling strain. A total of 30 cows and 30 calves on both farms were included in the study. Serum samples from cows were collected on calving day and serum samples from their respective calves on days 10, 20, 30, 45, 60, 75, 90, 105 and 120 after birth. Colostrum samples were collected only from 15 cows on one farm. In order to determine the presence of antibodies against LSDV a total of 30 cow sera samples, 15 colostrum samples and 270 calf sera samples were examined by commercial enzyme-linked immunosorbent assay (ELISA) and modified virus neutralization test (VNT). Overall, the performance of both serological tests was very satisfactory. The results of this longitudinal study showed that persistence of passive immunity in calves is less than 4 months, and that most calves are not protected against LSDV at that age. Since the vaccination is the most important control measure against LSDV, the recommended age of six months for vaccination of calves born to vaccinated cows should be reassessed to achieve the most optimal protection against LSD.

Geospatial Analysis of Lumpy Skin Disease Outbreaks among Cattle in Uttar Pradesh, India, 2021-2022

The emergence of lumpy skin disease (LSD) among cattle in India is concerning. District-level data on LSD cases in Uttar Pradesh between 2021 and 2022 were analyzed. A stepwise spatial analytical approach was followed by first constructing yearly and monthly disease maps for LSD incidence rates (IRs), then spatially interpolating the LSD IRs, followed by evaluating the global and local clustering of LSD IRs and finally conducting spatial regression modeling. Overall, 5784 LSD cases from 6 districts and 112,226 cases from 33 districts were detected in 2021 and 2022, respectively. In the incremental spatial autocorrelation analysis, the highest global clustering of LSD IRs for the 2022 outbreak was detected at 196.49 km. For the 2021 LSD outbreak, one district with high-low and nine districts with low-high LSD IRs were identified in the eastern region of the state. For the 2022 LSD outbreak, 13 districts with high-high and 7 districts with low-high LSD IRs were identified in the western part of the state. A geographically weighted regression model identified the impact of climate (temperature and humidity) and land cover (pasture, fallow, and non-agricultural land) on LSD IRs. The study results can aid animal health authorities in developing LSD prevention and control programs.

Development of a Synthesized Gene Unique to Lumpy Skin Disease Virus and Its Application in Serological Differentiation of Naturally Infected from Vaccinated Cattle with Attenuated Goat Pox Vaccine

Lumpy skin disease (LSD) is an important infectious disease caused by lumpy skin disease virus (LSDV) in bovine. LSDV, sheep pox virus (SPPV), and goat pox virus (GTPV) from the same genus Capripoxvirus (CaPV) of the Poxviridae family exhibit a nucleotide sequence similarity of up to 97%. Therefore, attenuated vaccines of GTPV and SPPV are often used to vaccinate cattle against LSD. However, available serological testing methods cannot accurately differentiate cattle vaccinated with GTPV from those infected with LSDV, posing a significant risk for disease spread. In this study, we developed a synthesized gene unique to LSDV as a differential antigen to detect serum antibodies specific to LSDV and differentiate naturally infected from vaccinated animals (DIVA). We used it for an in-house indirect enzyme-linked immunosorbent assay (iELISA), and no cross-reaction with positive sera for bovine viral diarrhea virus (BVDV), infectious bovine rhinotracheitis virus (IBRV), Mycobacterium bovis (M. Tb), Pasteurella multocida (P. multocida), and Mycoplasma bovis (M. bovis). The cut-off value (S/P%) was 30% for in-house iELISA. The corresponding diagnostic specificity was 100% (95% CI: 88.43-100), and the diagnostic sensitivity was 93.3% (95% CI: 77.93-99.18). The intra-assay coefficient of variation (CV) ranged from 1.08% to 4.11%, and the interassay CV was 0.00%-8.90%. Furthermore, 200 clinical serum samples were examined, in the vaccinated herd, there were no positive samples (0/141) indicating the strong differentiation ability of this method. On the other hand, in the infected herds, the overall positivity was 33.90% (20/59) (95% CI: 22.08-47.39). In summary, a valuable synthesized protein unique to LSDV was developed and showed a promising application in an iELISA with high specificity and sensitivity in differentiating cattle infected with LSDV from those vaccinated with GTPV.

Persistence of passive immunity in calves receiving colostrum from cows vaccinated with a live attenuated lumpy skin disease vaccine and the performance of serological tests

This study aimed to determine the persistent duration of maternal immunity against lumpy skin disease virus (LSDV) in dairy calves born from vaccinated cows using a virus neutralization test (VNT). The performance of the VNT and an in-house-ELISA test was also determined. Thirty-seven pregnant cows from 12 LSD-free dairy farms in Lamphun province, Thailand were immunized with a homologous Neethling strain-based attenuated vaccine and calved from December 2021 to April 2022. Blood samples from dam-calve pairs were collected within the first week after calving. Subsequently, blood samples were taken from the calves at monthly intervals over a period of 4 months and tested for the humoral immune response using a VNT. The calf sera were also tested with an in-house ELISA test to estimate the accuracy of both tests using a Bayesian approach. For the results, antibodies against LSDV can persist in cows for 4-9 months post-vaccination. Moreover, neutralizing antibodies and LSDV-specific antibodies against LSDV were detected in the majority of calves (75.68%) during the first week after colostrum intake. However, the percentage of seropositive calves declined to zero by day 120, with seropositivity dropping below 50% after day 60. Only a small number of seropositive calves (approximately 13.51%) were observed on day 90. These findings indicated that passive immunity against LSDV can last up to 3 months. The median of posterior estimates for sensitivity (Se) and specificity (Sp) of the VNT were 87.3% [95% posterior probability interval (PPI) = 81.1-92.2%] and 94.5% (95% PPI = 87.7-98.3%), respectively. The estimated Se and Sp for the ELISA test were 83.1% (95% PPI = 73.6-92.6%) and 94.7% (95% PPI = 88.4-98.5%), respectively. In conclusion, this study illustrates the transfer and persistence of maternal passive immunity against LSDV to calves under field conditions. This highlights a potential three-month vaccination gap in calves born from vaccinated cows, while an in-house ELISA test can be used as an ancillary test for LSDV immune response detection. However, further research is required to assess the vaccination protocols for calves as young as 2 months old to precisely determine the duration of maternal immunity.

Space-Time Clustering and Climatic Risk Factors for Lumpy Skin Disease of Cattle in Uttar Pradesh, India, 2022

Lumpy skin disease (LSD), a transboundary infectious disease, negatively impacts cattle health and production. The first LSD outbreaks were reported in India in 2019, and since then, LSD spread to over 15 states, including Uttar Pradesh. This study evaluated LSD cases reported by veterinarians in Uttar Pradesh, India, during 2022. Using scan statistics, Poisson models that accounted for the background cattle population were constructed to identify spatial, temporal, and space-time clusters. A negative binomial regression model was built to assess the impact of temperature and humidity on the incidence rate (IR) of LSD. A total of 112,226 cases across 33 districts were reported in 2022. A purely temporal cluster with higher-than-expected LSD rates was identified between August and October 2022. Several purely spatial clusters were identified in the western part of the state. A primary space-time cluster was detected in west Utter Pradesh between August and October 2022 that overlapped with the spatial clusters. The secondary cluster occurred between September and October 2022 in the eastern part of the state. A rise in humidity (incidence rate ratio (IRR) = 1.39; 95% CI: 1.30-1.49) and temperature (IRR = 1.16; 95% CI: 1.06-1.27) increased the IR of LSD, suggesting a seasonality of the outbreaks. The results of this study can aid animal health authorities in developing effective LSD prevention, surveillance, and control strategies among cattle in India.

Susceptibility of Mediterranean Buffalo (Bubalus bubalis) following Experimental Infection with Lumpy Skin Disease Virus

Lumpy skin disease (LSD) is a viral disease of cattle and water buffalo characterized by cutaneous nodules, biphasic fever, and lymphadenitis. LSD is endemic in Africa and the Middle East but has spread to different Asian countries in recent years. The disease is well characterized in cattle while little is known about the disease in buffaloes in which no experimental studies have been conducted. Six buffaloes and two cattle were inoculated with an Albanian LSD virus (LSDV) field strain and clinically monitored for 42 days. Only two buffaloes showed fever, skin nodules, and lymphadenitis. All samples collected (blood, swabs, biopsies, and organs) were tested in real-time PCR and were negative. Between day 39 and day 42 after inoculation, anti-LSDV antibodies were detected in three buffaloes by ELISA, but all sera were negative by virus neutralization test (VNT). Cattle showed severe clinical signs, viremia, virus shedding proven by positive real-time PCR results, and seroconversion confirmed by both ELISA and VNT. Clinical findings suggest that susceptibility in buffaloes is limited compared to in cattle once experimentally infected with LSDV. Virological results support the hypothesis of buffalo resistance to LSD and its role as an accidental non-adapted host. This study highlights that the sensitivity of ELISA and VNT may differ between animal species and further studies are needed to investigate the epidemiological role of water buffalo.

Cracking the Code of Lumpy Skin Disease: Identifying Causes, Symptoms and Treatment Options for Livestock Farmers

The novel bovine viral infection known as lumpy skin disease is common in most African and Middle Eastern countries, with a significant likelihood of disease transfer to Asia and Europe. Recent rapid disease spread in formerly disease-free zones highlights the need of understanding disease limits and distribution mechanisms. Capripox virus, the causal agent, may also cause sheeppox and Goatpox. Even though the virus is expelled through several bodily fluids and excretions, the most common causes of infection include sperm and skin sores. Thus, vulnerable hosts are mostly infected mechanically by hematophagous arthropods such as biting flies, mosquitoes, and ticks. As a result, milk production lowers, abortions, permanent or temporary sterility, hide damage, and mortality occur, contributing to a massive financial loss for countries that raise cattle. These illnesses are economically significant because they affect international trade. The spread of Capripox viruses appears to be spreading because to a lack of effectual vaccinations and poverty in rural areas. Lumpy skin disease has reached historic levels; as a consequence, vaccination remains the only viable option to keep the illness from spreading in endemic as well as newly impacted areas. This study is intended to offer a full update on existing knowledge of the disease's pathological characteristics, mechanisms of spread, transmission, control measures, and available vaccinations.

Estimating the Transmission Kernel for Lumpy Skin Disease Virus from Data on Outbreaks in Thailand in 2021

Nationwide outbreaks of lumpy skin disease (LSD) were observed in Thailand in 2021. A better understanding of its disease transmission is crucial. This study utilized a kernel-based approach to characterize the transmission of LSD between cattle herds. Outbreak data from the Khon Kaen and Lamphun provinces in Thailand were used to estimate transmission kernels for each province. The results showed that the majority of herd-to-herd transmission occurs over short distances. For Khon Kaen, the median transmission distance from the donor herd was estimated to be between 0.3 and 0.8 km, while for Lamphun, it ranged from 0.2 to 0.6 km. The results imply the critical role that insects may play as vectors in the transmission of LSD within the two study areas. This is the first study to estimate transmission kernels from data on LSD outbreaks in Thailand. The findings from this study offer valuable insights into the spatial transmission of this disease, which will be useful in developing prevention and control strategies.

Development of a Real-Time qPCR Method for the Clinical Sample Detection of Capripox Virus

Capripox viruses (CaPVs), including sheep pox virus (SPV), goat pox virus (GPV), and lumpy skin disease virus (LSDV), are the cause of sheep pox (SPP), goat pox (GTP), and lumpy skin disease (LSD) in cattle. These diseases are of great economic significance to farmers, as they are endemic on farms and are a major constraint to international trade in livestock and their products. Capripoxvirus (CaPV) infections produce similar symptoms in sheep and goats, and the three viruses cannot be distinguished serologically. In this study, we developed a real-time quantitative polymerase chain reaction (qPCR) method for identifying CaPV in goats, sheep, and cattle. Clinical samples were tested and verified. The developed assay was highly specific for target viruses, including GPVSPV and LSDV, which had no cross-reaction with other viruses causing similar clinical symptoms. An artificially synthesized positive control plasmid using the CaPV 32 gene inserted into the vector pMD19-T was used as a template, and the correlation coefficient of the linear regression curve (R2) was 0.9916, the estimated amplification efficiency (E) was 96.06%, and the sensitivity (limit of detection, LOD) was 3.80 copies per reaction. Using the clinical samples as a template, the limit of detection (LOD) was 4.91 × 10-5 ng per reaction (1.60 × 10-5-2.13 × 10-3 ng, 95% confidence interval (CI)), which means that this method was one of the most sensitive detection assays for CaPVs. A total of 85 clinical samples from CaPV-infected animals (goats, sheep, and cattle) and 50 clinical samples from healthy animals were used to test and compare the diagnostic results using the Synergy Brands (SYBR) Green-based PCR method recommended by the World Organization of Animal Health (WOAH). Both diagnostic sensitivity (DSe) (95.8-100%, 95% CI) and diagnostic specificity (DSp) (92.9-100%, 95% CI) results of the real-time quantitative PCR (qPCR) and SYBR Green PCR were 100%, and the kappa value (κ) was 1.0 (1-1, 95% CI). In summary, the assay established based on TaqMan probes was advantageous in high specificity, sensitivity, and general applicability and could be a competitive candidate tool for the diagnosis of CaPV in clinically suspected animals.

Global Burden of Lumpy Skin Disease, Outbreaks, and Future Challenges

Lumpy skin disease (LSD), a current global concern, causes economic devastation in livestock industries, with cattle and water buffalo reported to have higher morbidity and lower mortality rates. LSD is caused by lumpy skin disease virus (LSDV), a member of the Poxviridae family. It is an enzootic, rapidly explorative and sometimes fatal infection, characterized by multiple raised nodules on the skin of infected animals. It was first reported in Zambia in 1929 and is considered endemic in Africa south of the Sahara desert. It has gradually spread beyond Africa into the Middle East, with periodic occurrences in Asian and East European countries. Recently, it has been spreading in most Asian countries including far East Asia and threatens incursion to LSD-free countries. Rapid and accurate diagnostic capabilities, virus identification, vaccine development, vector control, regional and international collaborations and effective biosecurity policies are important for the control, prevention, and eradication of LSD infections. This review critically evaluates the global burden of LSD, the chronological historical outbreaks of LSD, and future directions for collaborative global actions.

A Study of the Susceptibility of Laboratory Animals to the Lumpy Skin Disease Virus

This article presents the results of a study on the susceptibility of laboratory animals to the lumpy skin disease virus (LSDV). Mice weighing 15-20 g, hamsters weighing 40-60 g, guinea pigs weighing 600-1200 g, and rabbits weighing 2.5-3 kg were used in this study. Nodules were observed on the skin of rabbits and hamsters at the sites of inoculation. The virus was isolated from the affected skin areas in cell culture and examined using real-time PCR, indicating its tropism for animal skin. The production of anticapripoxvirus antibodies was detected using the neutralization reaction, starting from 10 days after infection in mice, 27 days in rabbits, and 14 days in hamsters. Some laboratory animals exhibited multiple skin nodules. This indicates that these animal species may play a role in maintaining the epizootic process.

Risk Factors and Spatiotemporal Distribution of Lumpy Skin Disease Occurrence in the Asian Continent during 2012-2022: An Ecological Niche Model

Lumpy skin disease (LSD) is an emerging transboundary infectious disease of animals with high morbidity and low mortality rates. The infection occurs in cattle, buffalo, and some closely related wild animals, with cattle and buffalo showing higher susceptibility than other species. The primary mode of disease transmission is the mechanical dispersion of bloodsucking insects. The disease symptoms, including animal fur damage, weight loss, decline in milk production, infertility, and miscarriage, lead to huge economic losses in regions and countries with LSD outbreaks. The present study aimed to analyze the incidence data of LSD in the Asian continent from January 2012 to September 2022, identify spatiotemporal clusters and risk factors of the disease, and establish a maximum entropy ecological niche model to predict high-risk areas for disease outbreaks. The studied variables included bioclimatic factors, land type, and population density. Following the screening process, 12 variables were included in the maximum entropy model. Among them, the variable contribution rates of cattle density, land cover, isothermality, buffalo density, and maximum temperature of the warmest month were 53.8%, 10.9%, 9.2%, 8.9%, and 8%, respectively. Accounting for more than 90% of the total variable contribution rate, these five variables were considered to be the important influencing factors of LSD outbreaks. According to the results, nine spatiotemporal clusters approximately matched the high-risk areas predicted by the model. The Caucasus region of Russia; the Russian border areas of Kazakhstan, Turkey, Syria, Lebanon, Palestine, and Israel; and the western regions of Iran, India, and Southeast Asia were predicted to be high-risk areas. Thus, this study provides the spatiotemporal clusters, risk factors, and high-risk areas of LSD outbreaks in the Asian continent, which can help formulate more effective disease prevention and control policies.

Update of Lumpy Skin Disease: Emergence in Asian Part of Eurasia

Lumpy skin disease (LSD) is an infectious disease mostly of cattle. The typical clinical picture is usually characterized by the appearance of multiple nodules on the skin and internal organs. They can cover the entire body of the animal in the course of severe illness. This disease causes serious economic damage despite the fact that mortality of cattle with LSD is often low. Now LSD is a serious danger for cattle in the Asian part of Russia (part of the territory of the Russian Federation geographically belonging to Asia) and the Southeast Asia. Initially LSD was an endemic disease in many Sub-Saharan African countries, then it spread to Asia and Europe. In order to prevent the spread of the lumpy skin disease virus (LSDV), strict quarantine is introduced, vector control is carried out and various other LSD control measures are implemented. An effective vaccination campaign is required to significantly reduce the morbidity. However, the risk of spreading this transboundary disease to neighboring LSDV virus-free countries and regions of Asia, remains high enough. This article contains a summary of the available information about the spread of LSD in Asian part of Eurasia for the period of 1984 - February 2022. We are also discussing the latest available findings on the epidemiology of LSD and the methods currently used for the prevention and control of the LSDV.

Isolation and molecular characterization of lumpy skin disease virus from hard ticks, Rhipicephalus (Boophilus) annulatus in Egypt

BACKGROUND

Lumpy skin disease (LSD), a disease of cattle and buffaloes, has recently become widely prevalent in Egypt. The aim of this study was to ascertain the potential role of Rhipicephalus (Boophilus) annulatus ticks in the transmission of this disease. Samples collected from suspected lumpy skin disease virus (LSDV) infected cows that had previously been vaccinated with the Romanian sheep pox virus (SPPV) in various Egyptian governorates were obtained between May to November over two consecutive years, namely 2018 and 2019. Ticks were morphologically identified and the partial cytochrome oxidase subunit I gene (COI) were sequenced, revealing that they were closely related to R. (Boophilus) annulatus. The G-protein-coupled chemokine receptor (GPCR) gene of the LSDV was used to test hard ticks.

RESULTS

Two positive samples from Kafr El-Sheikh province and one positive sample from Al-Behera province were reported. BLAST analysis revealed that the positive samples were closely related to the Kazakhstani Kubash/KAZ/16 strain (accession number MN642592). Phylogenetic analysis revealed that the GPCR gene of the LSDV recently circulating in Egypt belongs to a global cluster of field LSDV with a nucleotide identity of 98-100%. LSDV isolation was successfully performed four days after inoculation using 9 to 11-day-old embryonated chicken eggs showing characteristic focal white pock lesions dispersed on the choriallantoic membrane after three blind passages. Intracytoplasmic inclusion bodies, cell rupture, vacuoles in cells, and virus particles ovoid in shape were demonstrated by electron microscopy.

CONCLUSION

In this study the role of hard ticks in the transmission of the LSDV to susceptible animals in Egypt was revealed and confirmed by various methods.

Analysis of vaccine-like lumpy skin disease virus from flies near the western border of China

Lumpy skin disease (LSD) is a devastating viral disease that occurs in cattle. In China, it was first detected in the Xin-Jiang autonomous region, near the border with Kazakhstan, in August 2019. As there were no new occurrences of LSD in either country following the first detection, the initial introduction of the virus remains unknown. Arthropod vectors were considered as potential vectors. Consequently, to identify the arthropod vectors involved in transmitting LSD virus (LSDV), an insect surveillance campaign was launched at four different sites scattered along the border, and samples from 22 flying insect species were collected and subjected to PCR assays. Following the Agianniotaki LSDV vaccine and Sprygin's general LSDV assays, two kinds of non-biting flies, namely, Musca domestica L and Muscina stabulans, were positive for LSDV. However, all the other insects tested negative. Viral DNA was only detected in wash fluid, implying body surface contamination of the virus. The negative test results suggest that non-biting flies are the dominant insects involved in the observed local epidemic. Three genomic regions encoding RPO30, GPCR, and LW126 were successfully sequenced and subjected to phylogenetic analysis. The sequences shared high homology with LSDV/Russia/Saratov/2017, a recombinant vaccine-like strain formerly identified in Russia, and clustered with LSDV vaccine strains in phylogenetic trees of RPO30 and LW126. However, the GPCR gene was seen to be solely clustered with LSDV field strains, implying differences in host affinity between these closely related vaccine-like strains. Despite this, there is no direct evidence to support cross-border transmission of the vaccine-like LSDV. To our knowledge, this is the first report of vaccine-like LSDV DNA detection in non-biting flies in China.

Assessment of the control measures for category A diseases of Animal Health Law: Lumpy Skin Disease

EFSA received a mandate from the EC to assess the effectiveness of some of the control measures against diseases included in the Category A list according to Regulation (EU) 2016/429 on transmissible animal diseases ('Animal Health Law'). This opinion belongs to a series of opinions where these control measures are assessed, with this opinion covering the assessment of control measures for Lumpy Skin Disease (LSD). In this opinion, EFSA and the AHAW Panel of experts review the effectiveness of: i) clinical and laboratory sampling procedures, ii) monitoring period and iii) the minimum radius of the protection and surveillance zones, and the minimum length of time that measures should be applied in these zones. The general methodology used for this series of opinions has been published elsewhere; nonetheless, the transmission kernels used for the assessment of the minimum radius of the protection and surveillance zones are shown. Several scenarios for which these control measures had to be assessed were designed and agreed prior to the start of the assessment. The monitoring period was assessed as effective, and based on the transmission kernels available, it was concluded that the protection zone of 20 km radius and the surveillance zone of 50 km radius would comprise > 99% of the transmission from an affected establishment if transmission occurred. Recommendations provided for each of the assessed scenarios aim to support the European Commission in the drafting of further pieces of legislation, as well as for plausible ad hoc requests in relation to LSD.

Review: Vaccines and Vaccination against Lumpy Skin Disease

The geographical distribution of lumpy skin disease (LSD), an economically important cattle disease caused by a capripoxvirus, has reached an unprecedented extent. Vaccination is the only way to prevent the spread of the infection in endemic and newly affected regions. Yet, in the event of an outbreak, selection of the best vaccine is a major challenge for veterinary authorities and farmers. Decision makers need sound scientific information to support their decisions and subsequent actions. The available vaccine products vary in terms of quality, efficacy, safety, side effects, and price. The pros and cons of different types of live attenuated and inactivated vaccines, vaccination strategies, and associated risks are discussed. Seroconversion, which typically follows vaccination, places specific demands on the tools and methods used to evaluate the effectiveness of the LSD vaccination campaigns in the field. We aimed to give a comprehensive update on available vaccines and vaccination against LSD, to better prepare affected and at-risk countries to control LSD and ensure the safe trade of cattle.

Diagnosis of naturally occurring lumpy skin disease virus infection in cattle using virological, molecular, and immunohistopathological assays

Background and Aim:

Lumpy skin disease (LSD) is a contagious viral disease that has great economic losses among Egyptian breeding flocks. The present study was designed to compare the results of different diagnostic approaches used for the diagnosis of LSD virus (LSDV).

Materials and Methods:

A total of 73 skin nodule samples were collected from suspected infected cattle with LSDV from some Egyptian governorates during 2019 and 2020. Trials for virus isolation (VI) and identification on embryonated chicken eggs (ECEs) were conducted. Molecular detection, histopathological, and immunohistochemical examination were also conducted.

Results:

The virus was isolated into ECEs, and 58 samples of 73 were positive and gave a characteristic pock lesion on the chorioallantoic membrane. Twenty-two representative nodular skin specimens of the 58 positive samples were selected to be used for molecular, histopathological, and immunohistochemistry (IHC) diagnosis. Conventional polymerase chain reaction succeeded in detecting LSDV DNA in all tested 22 skin nodule samples. Histological examination of skins of different cases revealed various alterations depending on the stage of infection. IHC was used as a confirmatory test for detecting LSDV antigen in the tissues of the skin nodules of infected cattle using specific anti-LSDV antibodies. Lumpy skin viral antigen was detected within the cytoplasm of the epidermal basal cells layer and prickle cell and within the cytoplasm of the hair follicles’ epithelial outer and inner roots.

Conclusion:

This study confirmed the prevalence of LSDV infection in different Egyptian governorates during 2019 and 2020. In addition, histopathology and IHC could be potential methods to confirm Lumpy skin disease infection besidesVI and molecular detection.

Determination of production losses related to lumpy skin disease among cattle in Turkey and analysis using SEIR epidemic model

Background

Lumpy Skin Disease (LSD) is an infectious disease induced by the Capripoxvirus, causing epidemics in Turkey and several countries worldwide and inducing significant economic losses. Although this disease occurs in Turkish cattle every year, it is a notifiable disease. In this study, LSD in Turkey was modelled using the Susceptible, Exposed, Infectious, and Recovered (SEIR) epidemiological model, and production losses were estimated with predictions of the course of the disease. The animal population was categorized into four groups: Susceptible, Exposed, Infectious, and Recovered, and model parameters were obtained. The SEIR model was formulated with an outbreak calculator simulator applied for demonstration purposes.

Results

Production losses caused by the LSD epidemic and the SEIR model’s predictions on the disease’s course were evaluated. Although 1282 cases were identified in Turkey during the study period, the prevalence of LSD was calculated as 4.51%, and the mortality rate was 1.09%. The relationship between the disease duration and incubation period was emphasized in the simulated SEIR model to understand the dynamics of LSD. Early detection of the disease during the incubation period significantly affected the peak time of the disease. According to the model, if the disease was detected during the incubation period, the sick animal's time could transmit the disease (Tinf) was calculated as 2.66 days. Production loss from LSD infection was estimated at US $ 886.34 for dairy cattle and the US $ 1,066.61 for beef cattle per animal.

Conclusion

Detection of LSD infection during the incubation period changes the course of the disease and may reduce the resulting economic loss.

Prevalence, intensity, and impacts of non-cutaneous lesions of lumpy skin disease among some infected cattle flocks in Nile Delta governorates, Egypt

Lumpy skin disease (LSD) is one of the major viral diseases still causing great economic losses among breeding flocks of Egypt. This study was designed to focus light on non-cutaneous lesions (prevalence, intensity, and impacts) among necropsied LSD infected cattle. We selected some dairy and beef flocks (Frisian breed) located in 3 governorates (Sharkia, Dakahlia, and Kaloubia) in Nile delta, Egypt, in the period from January 2019 to January 2020 for our survey study. The case history of farms declared no previous vaccination of examined farms. The clinical signs, morbidity, and mortality rates were recorded. Average morbidity and mortality percentage were 22.28% and 6.59%, respectively. PCR for specimens from liver, kidneys, heart, lungs, testis, udder, trachea, and lymph node indicates presence of amplicon capripoxvirus gene product at molecular weight size 192 bp. Postmortem lesions of necropsied and emergency slaughtered were recorded. The main detectable histopathology lesions among the infected animals were orchitis (75%), mastitis in immature and lactating udder (66.66%), and necrotic hepatitis (77.77%), disseminated vasculitis (61.11), glomerulonephritis (55.55), myocardial degeneration (50%), and serous atrophy of coronary fats (38.88%), lymphadenitis (88.88%), necrosis and depleted lymphoid tissue of spleen (38.88%), necrotic myositis (77.77%), tracheitis (16.66%), and pneumonia (interstitial bronchopneumonia) (44.44%) besides intra-cytoplasmic inclusions bodies in skin (33.33%). It could be concluded that higher mortalities of LSD may be due to systemic infection of infected animals which had great impact on economic losses among breeding flocks.

The role of wildlife in the epidemiology and control of Foot-and-mouth-disease And Similar Transboundary (FAST) animal diseases: A review

Transboundary Animal Diseases (TADs) are notifiable diseases which are highly transmissible and have the potential for rapid spread regardless of national borders. Many TADs are shared between domestic animals and wildlife, with the potential to affect both livestock sector and wildlife conservation and eventually, public health in the case of zoonosis. The European Commission for the Control of Foot-and-Mouth Disease (EuFMD), a commission of the Food and Agriculture Organization of the United Nations (FAO), has grouped six TADs as 'Foot-and-mouth disease (FMD) And Similar Transboundary animal diseases' (FAST diseases). FAST diseases are ruminant infections caused by viruses, for which vaccination is a control option. The EuFMD hold-FAST strategy aims primarily at addressing the threat represented by FAST diseases for Europe. Prevention and control of FAST diseases might benefit from assessing the role of wildlife. We reviewed the role of wildlife as indicators, victims, bridge hosts or maintenance hosts for the six TADs included in the EuFMD hold-FAST strategy: FMD, peste des petits ruminants, lumpy skin disease, sheep and goatpox, Rift Valley fever and bovine ephemeral fever. We observed that wildlife can act as indicator species. In addition, they are occasionally victims of disease outbreaks, and they are often relevant for disease management as either bridge or maintenance hosts. Wildlife deserves to become a key component of future integrated surveillance and disease control strategies in an ever-changing world. It is advisable to increase our knowledge on wildlife roles in relevant TADs to improve our preparedness in case of an outbreak in previously disease-free regions, where wildlife may be significant for disease surveillance and control.

Capripoxvirus Infections in Ruminants: A Review

Lumpy skin disease, sheeppox, and goatpox are notifiable diseases of cattle, sheep, and goats, respectively, caused by viruses of the Capripoxvirus genus. They are responsible for both direct and indirect financial losses. These losses arise through animal mortality, morbidity cost of vaccinations, and constraints to animals and animal products' trade. Control and eradication of capripoxviruses depend on early detection of outbreaks, vector control, strict animal movement, and vaccination which remains the most effective means of control. To date, live attenuated vaccines are widely used; however, conferred protection remains controversial. Many vaccines have been associated with adverse reactions and incomplete protection in sheep, goats, and cattle. Many combination- and recombinant-based vaccines have also been developed. Here, we review capripoxvirus infections and the immunity conferred against capripoxviruses by their respective vaccines for each ruminant species. We also review their related cross protection to heterologous infections.

Lumpy skin disease in Kazakhstan

This study describes the registration of the first cases of lumpy skin disease in July 2016 in the Republic of Kazakhstan. In the rural district of Makash, Kurmangazinsky district of Atyrau region, 459 cattle fell ill and 34 died (morbidity 12.9% and mortality 0.96%). To determine the cause of the disease, samples were taken from sick and dead animals, as well as from insects and ticks. LSDV DNA was detected by PCR in all samples from dead animals and ticks (Dermacentor marginatus and Hyalomma asiaticum), in 14.29% of samples from horseflies (Tabanus bromius), and in one of the samples from two Stomoxys calcitrans flies. The reproductive LSD virus was isolated from organs of dead cattle and insects in the culture of LT and MDBK cells. The virus accumulated in cell cultures of LT and MDBK at the level of the third passage with titers in the range of 5.5–5.75 log 10 TCID50/cm³. Sequencing of the GPCR gene allowed us to identify this virus as a lumpy skin disease virus.

Entomological and Virological Methods for the Identification of Potential Vectors of Lumpy Skin Disease Virus in the South-Eastern Part of Northern Caucasus, Russia

The article provides assessment of field and laboratory methods for the collection and evaluation of potential vectors of lumpy skin disease virus (LSDV) in one of the districts of Krasnodarskiy Kray in southern Russia. In this study, we tested several methods of vector collection and a PCR protocol for the detection of the LSDV genome in insects. Descriptive data on samples were collected using a free web-based application Epicollect5.

Potential LSDV vectors are quite widely spread insects in this region. We identified 15 insect species, including Musca domestica, Musca autumnalis and Stomoxys calcitrans. Analysis of the insect population showed an increase in species diversity and a decrease in abundance of the insect population by the end of the flight season.

PCR tests did not detect LSDV genome in the collected samples. All the methods tested were found suitable for large-scale monitoring of lumpy skin disease (LSD). Further studies on potential risk factors of LSD spread are necessary to improve measures on preventing and eliminating the disease.

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.

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%.

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.

Mapping changes in the spatiotemporal distribution of lumpy skin disease virus

Lumpy skin disease virus (LSDV) is an infectious disease of cattle transmitted by arthropod vectors which results in substantial economic losses due to impact on production efficiency and profitability, and represents an emerging threat to international trade of livestock products and live animals. Since 2015, the disease has spread into the Northern Hemisphere including Azerbaijan, Kazakhstan, the Russian Federation and the Balkans. The rapid expansion of LSDV in those regions represented the emergence of the virus in more temperate regions than those in which LSDV traditionally occurred. The goal of this study was to assess the risk for further LSDV spread through the (a) analysis of environmental factors conducive for LSDV, and (b) estimate of the underlying LSDV risk, using a combination of ecological niche modelling and fine spatiotemporally explicit Bayesian hierarchical model on LSDV outbreak occurrence data. We used ecological niche modelling to estimate the potential distribution of LSDV outbreaks for 2014-2016. That analysis resulted in a spatial representation of environmental limits where, if introduced, LSDV is expected to efficiently spread. The Bayesian space-time model incorporated both environmental factors and the changing spatiotemporal distribution of the disease to capture the dynamics of disease spread and predict areas in which there is an increased risk for LSDV occurrence. Variables related to the average temperature, precipitation, wind speed, as well as land cover and host densities were important drivers explaining the observed distribution of LSDV in both modelling approaches. Areas of elevated LSDV risks were identified mainly in Russia, Turkey, Serbia and Bulgaria. The results suggest that, if current ecological and epidemiological conditions persist, further spread of LSDV in Eurasia may be expected. The results presented here advance our understanding of the ecological requirements of LSDV in temperate regions and may help in the design and implementation of prevention and surveillance strategies in the region.

Detection of antibodies against Lumpy skin disease virus by Virus neutralization test and ELISA methods

Infection of cattle with lumpy skin disease virus (LSDV) is very important from the aspect of livestock production. Although it can cause significant economic losses, available serological assays are still not sufficiently efficient and reliable. A 3-day VNT was performed using Madin-Darby bovine kidney (MDBK) cell line and LSDV isolated from clinically infected cow to improve serological diagnostics of lumpy skin disease (LSD).

In total, 325 cattle sera samples were tested in order to compare the performances of VNT and ELISA. Tested samples originated from 125 cows before the occurrence of LSD in the Republic of Serbia and 200 tested samples originated from vaccinated cows. Sera samples from vaccinated cows were collected starting from the vaccination day to 4 months after vaccination. In 7 different time intervals after vaccination sampling was carried out in 20 cows originating from one herd and in 3 different time intervals in 20 cows originating from a different herd each time of sampling.

Out of 200 samples from vaccinated cows, antibodies against LSDV were detected in 68 (34%) samples by VNT, and in 60 (30%) samples by ELISA. No positive finding was detected by VNT in samples collected before the occurrence of LSD in Serbia, while one positive finding was detected in the same samples by ELISA. The first presence of antibodies in vaccinated cattle was detected by both tests 20 days after vaccination, and the largest number of animals with antibodies against LSDV was detected 30 days after vaccination.

Comparing the results obtained by VNT and ELISA, it was calculated that kappa index was 0.913. The specificity of VNT and ELISA was 100% and 99.2%, respectively. VNT is simpler to perform compared to the recommended virus neutralization test by the OIE and can improve LSD serological diagnostics with additional sensitivity testing.

Lumpy skin disease: III. Data collection and analysis

In 2018, no lumpy skin disease (LSD) outbreaks were reported in the Balkan region, after the decline reported in 2017 (385) compared to 2016 (7,483). This confirms the effectiveness of the vaccination campaign based on the LSD homologous vaccine strain which continued throughout 2018 with over 2.5 million animals vaccinated, keeping the mean vaccination coverage above 70%. In 2018, LSD outbreaks were reported in Russia, Turkey and Georgia. In Russia, the LSD epidemics expanded northward and eastward, while in Turkey, the most affected region was in the east. LSD is spreading in Turkey since 2013, despite large vaccination campaigns with heterologous vaccine performed since 2014. This might support the hypothesis that the use of heterologous vaccines results in insufficient protection, and therefore, the use of homologous LSD vaccine in Turkey should be considered to prevent further spread. As the LSD epidemic in Turkey is a risk for reintroduction into the EU, it is recommended to continue the vaccination campaigns in 2019 in the high‐risk areas of Balkan region. Spread rates of LSD within a village were estimated from outbreak data for Albania, which can be used to inform the level of vaccination required to control an outbreak in a village. In terms of vaccine safety, the reports from the field suggest that, compared to the large number of animals vaccinated in the Balkan region since 2015, a very limited number of side effects have been recorded so far, although from published literature, local or even systemic side effects in some animals may occur after vaccination. However, due to inadequate study design in the reviewed studies, there is no consensus on the magnitude of such effects and on their real consequences on production.

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.

Spatial analysis of lumpy skin disease in Eurasia-Predicting areas at risk for further spread within the region

Data from affected lumpy skin disease (LSD) locations between July 2012 and September 2018 in the Balkans, Caucasus, and Middle East were retrieved from FAO's Global Animal Disease Information System (EMPRES-i) from the European Commission's Animal Disease Notification System (ADNS) and completed with data from the official veterinary services of some countries. During this period, a total of 7,593 locations from 22 countries were affected. Within this period, over 46,000 cattle were clinically affected by LSD, 3,700 animals died and 17,500 were slaughtered due to culling policies to stop the spread of the disease. Most outbreaks occurred in 2016, between the months of May and November. The affected region was divided into a grid of 10 × 10 km cells and we fit a spatial regression model to analyse the association between the reported LSD outbreaks and climatic variables, land cover, and cattle density. The results showed big differences in the odds of being LSD positive due to the type of land cover: the odds of a cell being LSD positive was increased in areas mostly covered with croplands, grassland, or shrubland. The odds was also increased for higher cattle density, as well as areas with higher annual mean temperature and higher temperature diurnal range. The resulting model was utilized to predict the LSD risk in neighbouring unaffected areas in Europe, the Caucasus, and Central Asia, identifying several areas with high risk of spread. Results from this study provide useful information for the design of surveillance and awareness systems, and preventive measures, e.g., vaccination programmes.

Lumpy skin disease: scientific and technical assistance on control and surveillance activities

The duration of the vaccination campaign sufficient to eliminate lumpy skin disease (LSD) mainly depends on the vaccination effectiveness and coverage achieved. By using a spread epidemiological model, assuming a vaccination effectiveness of 65%, with 50% and 90% coverage, 4 and 3 years campaigns, respectively, are needed to eliminate LSD. When vaccination effectiveness is 80% to 95%, 2 years of vaccination at coverage of 90% is sufficient to eliminate LSD virus (LSDV). For shorter campaigns, LSD is predicted to persist. When the infection is eliminated by vaccination, two pathways for disease recurrence are possible, (i) by new introduction from a neighbouring affected area, especially by introduction of infected animals, or, less likely (ii) the infection persisting either in the environment, in vectors or in wild animals. For planning surveillance, several elements should be considered: the objectives and related design prevalence, the epidemiological situation, the immunological status of the host population, the geographical area and the season, the type of surveillance (active or passive), the diagnostic methods including clinical detection (considered the most effective method for early detection of LSD), the target population, the sample size and frequency. According to the model, for early detecting new introductions of LSD, it may be needed to clinically check a large number of herds (e.g. 2–3,000 herds) monthly. Lower sample sizes can be considered, when a greater delay in detecting the virus is acceptable. Where vaccination is maintained, active surveillance for verifying the effectiveness of vaccination would be needed. Demonstrating disease absence can rely on serological surveillance, which should consider the test sensitivity, the design prevalence (estimated value: 3.5%), the onset and duration of serum antibodies. Important knowledge gaps on LSD are about within‐herd transmission, duration of protective immunity, role of vectors, diagnostic tests, farm location and type in the at‐risk countries and the epidemiological status of neighbouring countries.

Colostrum transfer of neutralizing antibodies against lumpy skin disease virus from vaccinated cows to their calves

The objective of the present study was to access the titres and duration of maternally derived neutralizing antibodies against lumpy skin disease virus (LSDV) in calves born to immunized dairy cows. The study was conducted in a Greek farm of 200 Holstein cows which were immunized with a homologous Neethling strain-based attenuated vaccine. Composite colostrum samples were obtained from 18 selected cows at the day of calving. Blood samples were obtained from each dam-calf pair prior to the first colostrum feeding and from the calves successively on the third day after calving and on monthly intervals thereafter, until day 150. Passive transfer of antibodies in calves was evaluated by determining the levels of total protein in serum samples collected on day 3. Neutralizing antibody (NAb) titres against LSDV in colostrum and serum samples were determined by virus neutralization test. Colostrum NAb titres >1:160 were associated with the presence of NAbs in serum from calves 3 days after birth. Out of the 18 calves, which received colostrum with NAbs, 16 (88.9%) had detectable NAbs in their serum. Thereafter, a declining percentage of calves with detectable serum NAbs was recorded (38.5% on day 90 and 0% on days 120 and 150). Only calves with high NAb titres on day 3 had detectable serum NAbs until day 90 after calving. Thus, a significant number of calves were not protected by maternal antibodies against the disease after the age of 3 months and likely even after the age of 2 months. The findings of the present study substantiate that current recommendation for vaccination can be amended, so as to minimize the susceptible bovine population and enable optimized LSD prevention and eradication.

Risk of introduction of lumpy skin disease in France by the import of vectors in animal trucks

BACKGROUND

The lumpy skin disease virus (LSDV) is a dsDNA virus belonging to the Poxviridae family and the Capripoxvirus genus. Lumpy skin diseases (LSD) is a highly contagious transboundary disease in cattle producing major economic losses. In 2014, the disease was first reported in the European Union (in Cyprus); it was then reported in 2015 (in Greece) and has spread through different Balkan countries in 2016. Indirect vector transmission is predominant at small distances, but transmission between distant herds and between countries usually occurs through movements of infected cattle or through vectors found mainly in animal trucks.

METHODS AND PRINCIPAL FINDINGS

In order to estimate the threat for France due to the introduction of vectors found in animal trucks (cattle or horses) from at-risk countries (Balkans and neighbours), a quantitative import risk analysis (QIRA) model was developed according to the international standard. Using stochastic QIRA modelling and combining experimental/field data and expert opinion, the yearly risk of LSDV being introduced by stable flies (Stomoxys calcitrans), that travel in trucks transporting animals was between 6 x 10-5 and 5.93 x 10-3 with a median value of 89.9 x 10-5; it was mainly due to the risk related to insects entering farms in France from vehicles transporting cattle from the at-risk area. The risk related to the transport of cattle going to slaughterhouses or the transport of horses was much lower (between 2 x 10-7 and 3.73 x 10-5 and between 5 x 10-10 and 3.95 x 10-8 for cattle and horses, respectively). The disinsectisation of trucks transporting live animals was important to reduce this risk.

CONCLUSION AND SIGNIFICANCE

The development of a stochastic QIRA made it possible to quantify the risk of LSD being introduced in France through the import of vectors that travel in trucks transporting animals. 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 vectors and 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 vectors and diseases.

Lumpy skin disease II. Data collection and analysis

The spatial and temporal patterns of lumpy skin disease (LSD) epidemics were analysed based on the data collected from affected and at-risk countries in southeastern Europe in 2016 and 2017. The reported outbreaks decreased from 7,483 in 2016 to 385 in 2017. Those were reported mainly in Albania in areas where vaccination was not completed. Only two and four outbreaks were reported in Greece and in the former Yugoslav Republic of Macedonia in 2017, respectively, where the herd immunity achieved by vaccination significantly reduced the further spread of the disease. However, this showed that the virus was still circulating and may re-emerge in not fully immunised animals. No further outbreaks were reported in the other countries that were affected in 2016, thus providing field evidence about the effectiveness of the regional vaccination campaign. The mathematical model fit to the Albanian data showed that the LSD spread is mostly up to 4 km with some longer distance transmission. The inclusion of relative vector abundance improves the model fit and supports that the abundance of potential LSD vectors is one of the major risk factors for LSD spread. This should be confirmed by field surveys on potential LSD vectors. The vaccination effectiveness in Albania, Bulgaria and Greece was estimated by survival analysis and Cox regression model to be 62%, 96% and 84%, respectively, and these results were validated by the mathematical model. This highlighted that the high coverage vaccination with the live homologous vaccine is the most effective measure for reducing lumpy skin disease virus (LSDV) spread. The housing type of animals was explored as risk factor in Greece, and the risk in farms with outdoor access was six times higher than in farms where animals are kept indoors, independently of vaccination status.

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.

Lumpy skin disease: I. Data collection and analysis

An epidemiological analysis of the temporal and spatial patterns of LSD epidemics and of the risk factors for LSD spread in south‐eastern Europe was performed, based on the data collected from affected and at risk countries. Since 2015, the extent of the LSD epidemics in south‐eastern Europe was over 7,600 LSD outbreaks with 12,800 affected animals, with most outbreaks occurring between May and August. Most LSD spread occurs over a relatively small distance, approximately between 10 and 20 km, and the speed of propagation was estimated to be mostly up 2 km/day, in agreement with the vector‐borne pattern of LSD. Proximity to affected farms, warm temperatures and related vector abundance were among the main risk factors for LSD spread. Within a few months’ at least 90% of the animal population had been vaccinated with live homologous vaccine against LSD in south‐eastern Europe. Where almost total vaccination coverage was achieved, no further outbreaks were reported. The vaccination effectiveness in Albania was estimated to be around 70% at farm level and 77% at animal level. Possible adverse effects to live homologous vaccine, including fever, decreased milk production and oedema at injection site were reported in Croatia (a LSD‐free country) mostly within 2 weeks after vaccination, in 0.09% of the vaccinated animals. Unique farm identifiers should be always used across all databases, so to allow further analysis especially on improving the mathematical models for more robust estimates of transmission parameters applicable to the region, and for better estimation of vaccination effectiveness. All suspected clinical cases in vaccinated animals should be confirmed by differentiating field virus from vaccine strain. Trapping surveys for estimation of vector abundance can be carried out by targeting some sentinel farms, to be followed up during the whole LSD season, while long‐term studies can give more accurate information about species composition and seasonality of potential LSD vectors.

Long-term changes in the spatial distribution of lumpy skin disease hotspots in Zimbabwe

Outbreaks of lumpy skin disease (LSD) are reported almost every year in Zimbabwe but not much is known regarding whether the pattern of the disease is changing in response to major socio-economic programmes such as the land reform launched in 2000. In this paper, geo-referenced data of LSD cases was used to detect and map significant LSD hotspots over a 20-year period (1995-2014). The hotspots were then overlaid on top of a land tenure map to explore whether hotspots have spread or persist in some land tenure types. The main results are that LSD outbreaks are on the rise and the disease is spreading throughout the country with areas formerly large-scale commercial farms now experiencing more outbreaks. These results suggest that regular vaccination should be now recommended in most districts in the country.

Epizootology and Molecular Diagnosis of Lumpy Skin Disease among Livestock in Azerbaijan

Lumpy skin disease (LSD) is a viral disease of livestock that can cause cutaneous and internal lesions, affecting milk production, hide quality and in some cases death of the infected animal. After an outbreak in neighboring Iran, a working group from the Azerbaijan State Veterinary Control Service was sent to the border rayons (administrative districts) to determine if any cattle in southern Azerbaijan were infected. The Rayonal Veterinary Offices were contacted to look for and report any cases of LSD in their rayons. Animals exhibiting clinical signs consistent with LSD infection were first observed in the rayon of Bilasuvar and more cases were subsequently identified in Jalilabad, Ujar, and Aghdash rayons. Samples were collected from blood, and/or lesions of suspected infected animals and internal organs of cattle that died and were tested at the Republican Veterinary Laboratory in Baku using real-time polymerase chain reaction (PCR). From June to November 2014, 2,762 cattle in Azerbaijan were reported to have clinical signs or gross necropsy lesions consistent with LSD. Of 269 samples tested for LSD virus by real-time PCR, 199 (74%) were positive. A total of 33 cattle died, which was 1.2% of those exhibiting clinical signs of disease. Samples from nodular cutaneous lesions were more frequently positive by PCR and had higher concentrations of virus than blood and pooled internal organ samples. Preventative measures including movement restrictions, vector control and vaccination were put into place to slow the spread of disease. Ongoing surveillance should continue as environmental persistence of the virus may lead to further outbreaks of disease.

Emergence of Lumpy Skin Disease in Greece, 2015

Lumpy skin disease was first reported in the EU, Greece, in August 2015. Until the end of December 2015, six regional units have been affected in northern Greece and the island of Limnos. This article presents the epidemiological situation, the diagnosis, the control measures including emergency vaccination and the preliminary conclusions from the experience gained.

Comparison of the efficacy of Neethling lumpy skin disease virus and x10RM65 sheep-pox live attenuated vaccines for the prevention of lumpy skin disease - The results of a randomized controlled field study

Lumpy skin disease (LSD) is a viral disease of cattle and buffalo, caused by a Capripox virus. A field study was performed during an LSD epidemic which occurred in 2012-2013 in Israel, in order to assess the efficacy of two commercial vaccines for protection against LSD. Fifteen dairy herds, vaccinated 2-5 months prior to study onset with a single dose of 10(2.5) TCID50 of RM65 attenuated sheep-pox vaccine, and not affected previously, were enrolled in the study. 4694 cows were randomized to be either vaccinated with a 10(3.5) TCID50/dose of RM65 vaccine (x10RM65) or with a same dose of an attenuated Neethling LSD virus vaccine. A case of LSD was defined as the appearance of at least 5 lesions typical to LSD and a severe case was defined if this sign was accompanied by either fever (>39.5°C) or/and a 20% reduction in milk production. Deep lesion biopsies and blood samples were collected from 64.5% of the cases in an attempt to detect DNA of LSD virus by PCR and to differentiate between the wild strain and the vaccine Neethling strain. Seventy-six cows were affected by LSD in 8 herds with an incidence of 0.3-5.7%. Mantel-Haenszel relative risk (RRMH) for LSD morbidity at least 15 days after vaccination in x10RM65 vs. Neethling was 2.635 (CI95%=1.44-4.82) and 11.2 (2.3-54.7) for severe morbidity. RRMH for laboratory confirmed cases was 4.28 (1.59-11.53). An incidence of 0.38% (9/2356) of Neethling associated disease was observed among Neethling vaccinated cows while no such disease occurred in x10RM65 vaccinated cows. We conclude that the Neethling vaccine is significantly more effective than x10RM65 in preventing LSD morbidity, though it might cause a low incidence of Neethling associated disease. No transmission of the Neethling strain to non-Neethling vaccinated cows was observed in this study.