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Managing transboundary disease risks to Australia

Peter Windsor, Production Animal Welfare & Health Services, Scarborough, NSW 2515

Posted Flock and Herd November 2024

Introduction

This article provides reflections on the risks of transboundary diseases (TADs) to Australia. This follows extensive 'hands-on' experiences commencing in 1998 in several countries in the region of South East Asia (SEA), considered the most likely source of TAD risk to Australia. The objective is to share knowledge of the enormous and dynamic challenges in the regional control of Foot-and-Mouth Disease (FMD) and other emerging infectious diseases (EIDs) of farmed animal populations, plus describe interventions that may assist. It is important to recognise that addressing the regional TAD risks requires an understanding that as livestock production systems in SEA remain so very different to those we experience in Australia, TAD control will most likely remain extremely challenging.

SEA farming systems are dominated by the inefficient smallholder 'animal keeper' system, compromising low-level literacy, very limited resource availability and an historical preference for unhygienic 'wet market' processing and trading that avoids refrigeration and often, food safety and quality assurance. Further, the ineffective development of local and regional biosecurity and other disease prevention services by under-funded national and international livestock services persists, with any improvements only slowly adopted, particularly in the Greater Mekong Sub-region (GMS).

That these and other risk factors have persisted for decades, despite evidence of a sustained period of rapidly expanding regional demand for animal-sourced foods, is frustrating. That the risks of regional transboundary disease incursions have also been increasing is also clearly evident and increasingly problematic. Regular arrival of new strains of Foot-and-Mouth Disease virus in SEA has accompanied persistent circulation of endemic strains, with loss of general population immunity following the inevitable replacement by vulnerable animals. Similarly, repeated occurrences of Highly Pathogenic Avian Influenza (HPAI), has been accompanied by recent arrival of epidemics of African Swine Fever (ASF), Porcine Reproductive and Respiratory Syndrome (PRRS), Lumpy Skin Disease (LSD) and Peste Petits Ruminants (PPR) in SEA and beyond.

That the COVID pandemic emerged in the vicinity of SEA reflects that these factors are of relevance to managing One Health (OH) concerns, including EIDs, zoonoses and increasing antimicrobial resistance (AMR). Further, the slow adaption to increasingly deleterious climate impacts is apparent in countries where increasingly severe floods, droughts, hyperthermia and hypothermia episodes from weather event volatility, has been emerging. Yet these are occurring in countries with some of the highest Emission Intensities (EI) of global ruminant animal production, indicating there are severe regional Ecosystem health (EH) challenges. So what is to be done?

MATERIALS & METHODS

So-called 'wicked' problem solutions require detailed analysis for better problem definition. That has led to many studies within programs and projects, funded by a range of both national and international agencies, all providing aspects of enlightenment, but largely without a cohesive intervention or 'quick fix' that can be applied across all countries. One challenge is that these are countries in varying stages of historical development, each with their own sovereign rights to prioritise policy and resource allocation. An attempt to harness and document aspects of this work led by our collaborative efforts, has led to the creation of the 'Mekong Livestock Research and Beyond' (MLR&B) website, where blogs, project descriptions, training materials, scientific and other publications are all freely provided and have informed preparation of this document.

Two recent projects described on MLR&B, have been (i) an evaluation of the ongoing 'South East Asia Foot-and-Mouth Disease' (SEAFMD) campaign that commenced in 1997 and (ii) an innovation to improve productivity and animal health whilst addressing greenhouse gas emissions (GHGe) from large ruminants, leading to formation of an international 'climate smart' animal feed company, AgCoTech Global.

The SEAFMD initiative developed into SEACFMD program with addition of China and other nations. The campaign promotes international collaborative activities, involving 6 phased roadmaps, with Phase 6 (2021-2025) proposing an overall campaign evaluation. To progress this, a survey tool was developed using the Organization for Economic Cooperation and Development (OECD) monitoring and evaluation criteria of: relevance; coherence; effectiveness; efficiency; impact; and sustainability. Data from stakeholder online interviews (n=35), questionnaire survey (n= 58), and face-to-face focus group discussions (n=34) from the 26th SEACFMD Coordinators Meeting in Bali in October 2022, were analysed. As recent programs have included the Progressive Control Pathway (PCP) for FMD and the Performance of Veterinary Services (PVS) tools, opinions were sought on whether these had assisted regional FMD control, as were comments on whether the program had influenced progress in a range of equity issues (e.g. welfare, gender issues).

The search for initiatives that deliver convenient interventions in addressing livestock health deficits in developing countries, led to a series of projects incorporating anthelmintics in molasses nutrient blocks for improved endoparasite control. This was relevant in the GMS as few farms have animal restraint facilities for administration of medications. Initial studies in Laos with anthelmintic-medicated or urea-inclusive molasses blocks, demonstrated significantly improved bovine productivity. It was calculated that these improvements could have contributed indirect abatement of 470kg CO2eq/20kg block consumed. Studies of additional supplements in the block were initiated to investigate the impacts of supplements providing direct abatement of GHGe, with their inclusion to develop Emissions Control Blocks (ECBs). Housed dairy buffalo (n=7) and pasture-fed grazing beef cows (n=11) were randomly selected, body condition scores estimated (BCS:1-5) and baseline nasa-oral methane eructation measured daily for 2 weeks, using a hand-held methane monitor. The animals were offered 300-400g/day for a month of a supplement mix containing condensed tannins (CT) in a citral extract from a locally available aromatic herb.

Results

The review of the Southeast Asia China FMD program from 1997-2022, confirmed issues of: insufficient biosecurity with unregulated animal movements; difficulties of vaccine resourcing and delivery; inadequate funding of technical services for disease surveillance; low-level engagement of smallholders in disease control; deficient national emergency disease response capacities; and difficulties in co-ordination of international programs. Increased funding of TAD/OH/EH control programs in endemically-infected countries was advised to address these issues, particularly promoting biosecurity and surveillance for TADs, AMR and zoonoses in delivering climate resilient livestock systems.

A major project has been proposed and designed through the Asian Development Bank (ADB) entitled 'GMS Cross-border Livestock Health and Value Chains Improvement Projects'. This is potentially transformational, upscaling livestock husbandry and health knowledge, practices and infrastructure, enabling more sustainable food security in Lao PDR and Cambodia. However, governance and advocacy including cross-sectoral collaborations, with support for adoption of new dietary and health initiatives to reduce high levels of methane emission intensity and diminish AMR risks in the smallholder production system in the GMS, are required if TAD/OH/EH management is to be rapidly improved.

Studies on a convenient method of improving productivity and addressing international greenhouse gas emissions abatement, identified that both productivity enhancements (indirect abatement) and dietary supplements (dietary abatement) contribute to reductions in methane emissions (mainly at eructation) from large ruminants. It was recognised that high emissions intensity from regional cattle production occurs in Laos, estimated at 102.90 CO2eq/kg meat produced, compared with the average global EI of 30.28 and 22.01 CO2eq/kg in Australia. Average methane concentration per animal declined during the supplementation period by 36% in buffalo and 18% in cattle. This extract was then incorporated into ECBs manufactured in a new factory built in northern Laos with operations commencing in April 2023. Recent field trials in smallholder beef cattle in Cambodia with these Lao-manufactured ECBs, achieved combined (direct and indirect) methane abatement of 32%.

As of February 2024, over 30,000 ECBs have been distributed 'free' to smallholder farmers in 40 villages in Laos in exchange for verified carbon credits for purchase by global businesses seeking GHGe abatement. Delivery of ECBs is accompanied by preventive health interventions to reduce GHGe from diseases. GHGe abatement from consumption of ECBs by large ruminant, particularly in countries where EI from meat production is high, may contribute to mitigation of climate crisis and food insecurity concerns whilst improving rural livelihoods, livestock health and welfare in developing nations.

Discussion

Reflections on the multitude of studies conducted by our MLR&B team members, collaborators and the findings of others working in the SEA livestock sector, have led to a conclusion that future efforts in SEA food security requires delivery of three major strategies, including:

1. Transitioning smallholder keepers to production efficiencies with food safety

Facilitating adaption to modern livestock production systems in the GMS requires that smallholders alter consideration of their large ruminants from a 'cash reserve' to a food producing asset that can be value-added, and increasingly directed at a premium market aligned to the rapidly rising demands for increased quantity and quality of animal-sourced foods. Whilst the most recent strain of FMD in SEA is the O/ME-SA/Ind-2001e Sublineage, other strains are still circulating. Further, there is an emerging risk of FMD serotype SAT2 that usually circulates only in Africa and is now identified in the Near East, with risks to the GMS where most animals are fully susceptible to this virus. Risk assessments confirm that spread of FMD SAT2 to unaffected countries via key risk pathways is plausible, particularly with the persistence of informal movements of live animals and shared common grazing. These biosecurity deficits enable direct live animal contact for effective FMD virus transmission.

As outbreaks of FMD negatively impact food security, economies, labour markets and livelihoods, all countries require effective emergency response plans. This still does not appear to be a priority for several GMS countries, where inadequate detection and response capabilities for TAD and OH threats, including zoonoses and AMR, persist. AMR inflicts significant mortality, morbidity and economic loss in the 11 countries in the WHO SEA Region. Whilst all countries having developed National Action Plans on AMR that align with the Global Action Plan, most have observed trends of increasing drug resistance, despite heightened awareness and actions, with progress on AMR considered to be fragmented. The low technical capacity and resources, a weak regulatory framework, and slow behavioural changes at all levels of the value chain in developing shared antimicrobial stewardship, currently prevent effective application of interventions in animal production systems that can minimise the impacts of AMR.

Of concern to both managing AMR and improving disease surveillance and response capacity in smallholder livestock systems has been the dependence on community animal health workers (CAHW) having only rudimentary training and a focus on delivery of therapeutics. In the GMS, studies of Village Animal Health Worker (VAWH) practices in Cambodia identified that many are no longer active, incomes are poor, few are women, and most operate at minimal levels of effectiveness for surveillance, with few incentives for continuing their work. Their dependence on persistent use of routine antibiotic cover for viral diseases is of concern, particularly with repeated incursions of TADs and increasing emergence of AMR. Suggestions for an improved CAHW services model include: disease prevention and biosecurity with whole of village FMD and HS vaccination, regular endoparasite control, delivery of local quarantine; provision of reproductive services with artificial breeding, pregnancy diagnosis with welfare-appropriate surgical husbandry for castration and dehorning; and increasingly, nutritional services, including enabling forage plantation management and molasses blocks advisory services, potentially for carbon credit transactions for bovine methane abatement. Of these, programs that focus the CAHW role towards disease prevention rather than treatment, is critical for improved OH outcomes.

2. Apply biosecurity strategies of the SEACFMD program and COVID-19 responses

Although there are World Organisation for Animal Health (WOAH) global eradication plans for rabies, tuberculosis, PPR, ASF and FMD, it has been FMD as the priority disease for building more effective global disease control capacities. FMD has remained endemic in SEA for ~150 years, with piecemeal control measures until SEACFMD was initiated that led to the launch of the Global Framework for the Progressive Control of Transboundary Animal Diseases (GF-TADs) in 2004. This aimed for global prevention, detection, and control of TADs via regional and global dimensions, combining the strengths of international organisations to achieve agreed common objectives. The SEACFMD campaign facilitates a plethora of activities described in a series of phased roadmap documents, now using PCP-FMD and PVS tools. Both tools have been important in: (i) enabling a comparative step-by-step approach in the PCP to progressively increase control of FMD through their National FMD Control Plans; and (ii) regular conduct of a PVS audit to illuminate the deficits and record improvements in national veterinary services. Currently Laos is on PCP 2, Cambodia on PCP 1, with neighbouring countries all having a higher status with the exception of Indonesia since losing FMD Freedom status after a period of disease freedom of nearly 40 years; clearly a setback for SEACFMD.

Despite the loss of FMD freedom status in Indonesia, the SEACFMD evaluation of ~100 SEACFMD participants found many strengths, with general agreement that the expansion of SEAFMD through SEACFMD to involve more countries in the region beyond the GMS was appropriate, particularly with increasing interconnectedness of FMD virus pools occurring. There was also agreement that the evolving phases of the SEACFMD Campaign was robust, particularly since introduction of the PVS and PCP-FMD tools and despite repeated incursions of FMD and HPAI, plus ASF, LSD, PPR and other TADs into the region. Although the SEACFMD campaign has been successful in progressing relationships, coordination and communication, successes in obtaining political and financial commitments for sustainable control was considered insufficient.

More effective FMD control requires improved regional biosecurity, with reduced informal movement of livestock and their products throughout SEA. The persistence of 'informal' livestock movement indicates widespread failure to understand the importance of regional biosecurity in protection from FMD. Without biosecure livestock and animal product movement, there is dependence on increasing FMD vaccination, so far with limited success. Research has focused on vaccine serotypes and matching, strategies and efficacy, and delivery logistics and capacities to ensure vaccination programs are sustainable. The SEACFMD evaluation confirmed ongoing issues that can assist setting of future priorities, including: insufficient biosecurity with unregulated animal movements; difficulties of vaccine resourcing and delivery; inadequate funding of technical services with poor disease surveillance; low-level engagement of smallholders in disease control; deficient national emergency disease response capacities; difficulties in co-ordination of international programs. Funding of TAD/OH/EH control in endemically-infected countries is urgently required.

3. Prioritise livestock development projects that upgrade capacities and infrastructure for biosecure production and processing, whilst facilitating commercial investments to assist delivery of 1 and 2

Our numerous R&D livestock projects in Laos and Cambodia indicate that there is a clear and present if not urgent requirement, to greatly upscale livestock husbandry and health knowledge, attitudes, practices and infrastructure, enabling a more sustainable food security system in the GMS. This requires international advocacy to encourage and support national governance to increase investments in and facilitation of cross-sectoral collaborations addressing TAD/OH/EH concerns. This includes the inevitable requirement to divert funding priorities to those supporting the adoption of dietary and health initiatives that both diminish AMR risks and potentially, reduce EI by methane abatement in inefficient livestock production systems.

Two examples of new initiatives that can facilitate this process are presented below. The first comprises a major livestock development project to address the majority of deficits in the animal foods supply chain. The second describes a new private sector commercial initiative to address GHGe from livestock that offers numerous leveraging opportunities to also address the deficits in the value chain.

(i) Cross-border Livestock Health & Value Chains Improvement Project (CLHVCIP)

This Asian Development Bank (ADB) project was designed through the difficult years of COVID-19 and is finally commencing the procurement phase. Whilst ambitious, the project is potentially transformational as it addresses the urgent need for investments in underfunded government livestock services and support for smallholder TAD/OH/EH management, especially in Cambodia and Laos. The project aims to strengthen livestock value chains through investments in infrastructure, capacity building and policy support. Expected outcomes include improved health, value chains, and formal trade in livestock and their products, aligned with a vision for the GMS to be a leading supplier of safe and environmentally friendly agriculture products.

(ii) Enable private sector investment for improved nutrition and GHGe responsiveness

A multi-intervention livestock development strategy involving a combination of nutritional and health interventions has been proposed as a 'scale-out' strategy to assist smallholder large ruminant livestock farming efficiency. ECBs reduce the carbon footprint of the livestock agrifood system through improved rumen digestion efficiency, reducing EI, with inclusion of compounds that provide direct abatement of methane, aligning directly to the aspirations of the Global Methane Pledge. High-quality ECBs may be a simple motivation for rural communities to improve livelihoods and food security whilst reducing GHGe from ruminants by as much as 30%. Morbidity and mortality in livestock production increases the EI (kg CO2eq/kg product) of products delivered through reduced meat and milk yields, although the magnitude of specific disease effects varies according to the degree of output losses, disease prevalence and the characteristics of the population. It has been estimated that reducing FMD in beef cattle from 45% to 5% prevalence reduces GHGe EI by ~10%.

The introduction of molasses blocks to Laos was initiated for delivery of anthelmintics on farms lacking both cattle handling facilities and endoparasite control. In particular, control of Toxocara vitulorum in calves with fenbendazole blocks and Fasciola gigantica control in adults with triclabendazole blocks was achieved. Success encouraged the use of urea blocks in beef cattle for dry season feeding and in dairy buffalo for increased milk yields. Whilst improved productivity through nutrition and health from these blocks encouraged examination of the impacts on EI and the calculation that each 20kg block reduces EI by 470 kg CO2eq, inclusion of GHGe reducing agents in the ECB provides direct abatement of methane in the vicinity of ~800kg/C02eq per block, or ~32% (unpublished).

Positive feedback from farmers using ECBs describes improved productivity, animal appearance and values, with declarations that the blocks greatly assisted the management of their animals. This encouraged the development of a molasses block manufacturing facility in northern Laos near Luang Prabang that opened in April 2023 and is now producing ~3,000 blocks per month, with ECBs distributed free to farmers in exchange for the verified carbon credits accrued. Over 45 villages have received over 11,500 ECBs since July 1st 2023 and the plant will contribute ~150,000 ECBs in 2024 with a likely minimum abatement contribution up to 100,000 t of CO2e. This success likely increases the motivations of farmers to adopt 'risk management' including disease preventive vaccines and therapies, plus potentially adopt biosecurity and welfare interventions. A proposed 'whole of village' strategy to accompany distribution of ECBs includes a field audit of production and a disease risk assessment, enabling issues to be addressed that could compromise performance of the ECBs.

Improved animal production, health and welfare has been slow to gain traction, despite rapidly improving economies in the SEA region that has created a sustained increase in demand for livestock and their products. The surging demand has increased both TAD risks from extended informal livestock movements, AMR risk from unregulated antimicrobial use and minimal AMR stewardship, and EID risks from sub-standard slaughtering facilities and persistence of unhygienic 'wet markets' where the sale of wildlife adjacent to livestock is often still tolerated.

The use of highly visible interventions capable of creating rapid system change by motivated farmers and other stakeholders and that overcomes resistance to change, are urgently required. Access to ECBs to increase productivity and improve management, accompanied by leveraging targeted health surveillance and preventive strategies, including vaccination and endoparasite control to reduce disease risk, are suggested as most likely to drive these practice changes. There is a desperate need to create a more receptive environment for the change management required to progress both animal health and welfare through productivity innovations, assisting GHGe mitigation from the currently inefficient livestock systems, particularly in developing countries in the GMS and beyond.

Acknowledgements

The ongoing work that informs this contribution, reflects the efforts of a vast range of collaborators working closely with MLR&B, some continuously, since 2005. Their enormous efforts and camaraderie are most sincerely appreciated, as are those assisting projects through their roles in funding agencies.

References

  1. Asian Development Bank, Cambodia: Greater Mekong Subregion Cross-Border Livestock Health and Value Chains Improvement Project (2022) www.adb.org
  2. AgCoTech Global (2023) Reducing Smallholder Farmer Poverty. Fighting Climate Change. agcotechglobal.com
  3. Blacksell SD, Siengsanan-Lamont J, Kamolsiripichaiporn S, Gleeson LJ & Windsor PA (2019) A history of FMD research and control programmes in Southeast Asia: lessons from the past informing the future Epidemiology Infection 147e171:1-13 doi.org
  4. Business Partnership Platform Project: Enhancing livelihoods of smallholder farmers in Laos project (2019) thebpp.com
  5. Capper JL (2023) The impact of controlling diseases of significant global importance on greenhouse gas emissions from livestock production One Health Outlook 517 doi.org
  6. Mekong Livestock Research and Beyond: Our children now go to university. Improving rural livelihoods through livestock developments in Cambodia (2018) mekonglivestock.wordpress.com
  7. Mekong Livestock Research and Beyond: Molasses block factory opened in Laos (2023) mekonglivestock.wordpress.com
  8. Miller CAJ, Young JR, Nampanya S, Khounsy S, Singanallur NB, Vosloo W, Abila R, Hamilton SA, Bush RD & Windsor PA (2018) Risk factors for emergence of exotic foot-and-mouth disease O/ME-SA/Ind-2001d on smallholder farms in the Greater Mekong Subregion Preventative Veterinary Medicine 159:115-122 doi.org
  9. Rast L, Toribio J-AML, Dhand NK, Khounsy S & Windsor PA (2021) Why is a simple control option for Toxocara vitulorum not being implemented by cattle and buffalo smallholder farmers in South-east Asia? Preventative Veterinary Medicine 113:211-218 doi.org
  10. Ratyotha K, Prakobwong S & Pirataee S (2022) Lumpy skin disease: A newly emerging disease in Southeast Asia. Veterinary World 15:2764-2771 doi.org
  11. Ryoo S, Lee H, Lim DR, Lee JW, Bunnary S, Tum S, Lee DS, Hwang H, Jeong S, Nah J, Ku BK, Kim JM & Cha SH (2021) Identification of the O/ME-SA/Ind-2001e Sublineage of Foot-and-Mouth Disease Virus in Cambodia Frontiers in Veterinary Science 8:749966 doi.org
  12. Sieng S, Patrick IW, Windsor PA, Walkden-Brown S, Kerr J, Sen S, Sar S, Smith RGB & Kong R (2022) Contributions of village animal health workers to foot-and-mouth disease control in Cambodia Transboundary and Emerging Diseases 69:e406-e422 doi.org
  13. Windsor PA, Freeman PG, Abila R, Benigno C, Nim V & Cameron A (2011) Control and eradication of Foot and Mouth Disease in the Bicol surveillance buffer zone in the Philippines Transboundary and Emerging Diseases 58:421-433 doi.org
  14. Windsor PA, Nampanya S, Kinnavong B, Phommasone P, Bush RD & Khounsy S (2019) Do triclabendazole medicated molasses blocks have a role in control of Fasciola gigantica in smallholder cattle production in Lao PDR? Animal Production Science 59:787-793 doi.org
  15. Windsor PA, Martin S, Khounsy S, Young J, Thomson P & Bush RD (2021) Improved milk production from supplementation of swamp buffalo with molasses nutrient blocks containing 10% urea Dairy 2:90-103 doi.org
  16. Windsor PA & Hill J (2022) Provision of High-Quality Molasses Blocks to Improve Productivity and Address Greenhouse Gas Emissions from Smallholder Cattle and Buffalo: Studies from Lao PDR Animals 12:3319 doi.org
  17. Windsor PA (2024) Perspectives on progression of transboundary disease, one health and ecosystem health management in the Greater Mekong Subregion and beyond Animal Production Science 64:AN23431 doi.org
  18. Young JR, Evans-Kocinski S, Bush RD & Windsor PA (2015) Improving smallholder farmer biosecurity in the Mekong region through change management Transboundary and Emerging Diseases 62:491-504doi.org

 

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