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Addressing the dual emerging threats of African Swine Fever and Lumpy Skin Disease in Europe (DEFEND)

Periodic Reporting for period 2 - DEFEND (Addressing the dual emerging threats of African Swine Fever and Lumpy Skin Disease in Europe (DEFEND))

Reporting period: 2019-12-01 to 2021-05-31

DEFEND is an international partnership of academic, industrial and governmental organisations working together to tackle the emergence of African swine fever (ASF) and lumpy skin disease (LSD) in European livestock. Our overall objective is to control the growing ASF and LSD epidemics in Europe and neighbouring countries by understanding the drivers of ASFV and LSDV emergence, and generating research outputs which underpin novel diagnostic tools and vaccines, and authenticate appropriate and rapid responses by decision-makers.

African swine fever is an emerging disease that is currently spreading through pig populations in eastern Europe and Asia. The disease is caused by African swine fever virus (ASFV), is highly contagious, and causes a haemorrhagic syndrome which kills up to 100% of pigs in a herd. ASFV has caused the death of millions of pigs in Europe and Asia in recent years either directly or as a consequence of culling of infected herds. No vaccine exists to prevent disease, and control is heavily dependent on strict biosecurity measures.

Lumpy skin disease is an emerging disease of cattle. It is caused by the vector-borne poxvirus lumpy skin disease virus (LSDV). Since 2012 the virus has spread from the Middle East into new regions including Europe, Russia and Asia. An extensive regional vaccination campaign in south east Europe from 2016 - 2018 halted the spread of the disease further into central Europe, however it remains a threat to cattle populations worldwide.

DEFEND is designed around three scientific objectives:
• Objective 1. Identify the drivers for emergence of ASF and LSD in Europe
• Objective 2. Understand the fundamental biology of LSDV
• Objective 3. Develop tools for the management of ASF and LSD

The societal impact of DEFEND will be realised through reductions in economic losses in the farming sector, improved food security, heightened stability of the rural sector, and enhanced resource efficiency.
Objective 1. Identify the drivers for emergence of ASF and LSD in Europe
• A systematic literature search identified potential risk factors for entry, spread or development of ASF and LSD. Over 1000 publications for ASF and over 500 publications for LSD were sourced, reviewed by experts, and used to identify potential risk factors. These factors were then used for the development of a risk framework using a “Participatory risk mapping network for animal diseases” [PRMNAD] approach. This combines regional disease status with potential disease risk information. It can be used as a participatory tool and as a framework for the study of potential disease risk factors.
• Whole genome sequencing workflows for LSDV and ASFV have been optimised and sample panels collated from DEFEND Partner laboratories. LSDV samples have been collected, and genomes have been fully sequenced. Analysis is under way. The pipeline for sequencing the full genome of ASFV, including the complex repeat regions, has been developed and validated. Virus has been isolated from 15 samples from Lithuania from wild boar and domestic pigs, and the full viral genome sequenced from 7 to date.
• An extensive literature review has been undertaken into how civil wars, insecurity, conflicts and migrations could act as drivers for animal disease emergence and spreading, with particular attention paid to LSDV and ASFV. Data has also been sourced from media and press coverage, and “grey literature” (informal documents) in local languages. Fieldwork has started to investigate the potential drivers identified.

Objective 2. Understand the fundamental biology of LSDV
• Vector-borne LSDV transmission via Stomoxys calcitrans flies was evaluated using both in vivo and in vitro models. Indirect transmission of LSDV via fomites was also studied by analysing the survival of LSDV in different liquid matrices. Studies to estimate the risk associated with LSDV transmission via semen are underway.
• Clinical and subclinical forms of LSD have been compared using a bovine experimental model of LSD.


Objective 3. Develop tools for the management of ASF and LSD
• A decision tool for the evaluation of the risk of introducing ASFV into pig farms has been developing and is currently being trialled in the field.
• Mathematical models which simulate ASF in a wild boar population have been developed and used to identify the role of different factors on the progression of the disease.
• The immune response of cattle infected with LSDV has been characterised in detail. This information has been used to develop better tools for the serodiagnosis of LSD and to design novel LSD vaccines appropriate for use in non-endemic regions.

Cross-cutting themes
• Communication and dissemination. The DEFEND communication tools have been used to promote the work of DEFEND, including website, newsletters and social media. Key Performance Indices have been used to monitor our performance.
• Guaranteeing impact. The DEFEND Knowledge Transfer plan continues to provide a framework for our activities in this area. Training workshops have been undertaken, GAP analyses carried out, and an external review of DEFEND knowledge transfer has been carried out, with recommendations for future areas to focus on.
• Project Management. This theme ensures efficient progress of the planned work by providing administrative and coordination support, and by acting as the interface between DEFEND and the EC. Activities include organising consortium conferences, supporting collaborations, and promoting gender equality.
The impact of DEFEND is being realised through implementation of innovative solutions for the control and prevention of ASF and LSD. For example:
• The technical platform for the risk framework is able to explore explicit disease occurrences and risk factors regionally and timely at the interface of social science and epidemiology. We are developing it for LSD and ASFV, but it could be exploited to analyse risk factors for other transboundary diseases.
• A decision tool for the evaluation of the risk of introducing ASFV into pig farms has been developing and is currently being trialled. The tool will identify the level of risk of individual holdings, highlight the risk factors and target the proper disease control measures. This will minimize the risk of ASFV introduction.
• Mathematical models which simulate ASF in a wild boar population have been developed and used to evaluate the impact of different surveillance strategies, and to identify the role of different factors (such as hunting pressure, disease survivors, carcass removal) on the progression of the disease. The results from this modelling will be exploited by policy makers to design more effective strategies to reduce the spread of ASFV in wild boar, and to reduce the spill-over of ASFV from wild boar to pigs.
Tools and knowledge such as these will support the European animal health policy motto “prevention is better than cure”. Potential impacts include a reduction in the economic losses suffered by the farming sector, and improved food quality and security. These impacts will support EU animal health policies.
African swine fever and lumpy skin disease are rapidly emerging diseases of livestock