Introduction
Animal production systems generate economic and social goods to farmers, their communities and their countries. Animal diseases, however, hamper normal animal development and animal welfare, and can lead to fatalities. The effects of animal diseases on livestock productivity include reduced feed intake, changes in digestion and metabolism affecting the feed conversation rates, increased morbidity and mortality, impaired reproductive performance, and reductions in egg production and milk yield, amongst others. Thus, the impact of animal diseases on productivity is reflected in loss of production, increased disease control costs and loss of assets, marginalizing producers from higher-priced livestock markets and restricting their access and capacity for value-added trade. Furthermore, the impact of animal diseases should be regarded from a more holistic point of view, as besides animal health, they can also impact community livelihoods, public health, tourism and wildlife (Perry and Grace, 2009) (FAO, 2016).
Occurrence of major transboundary animal diseases greatly impact livestock production and can result in restrictions to international trade in livestock and livestock products. TADs refer to diseases with high transmissibility and morbidity, such as foot-and-mouth disease (FMD) or avian influenza, or with high mortality, such as peste de petit ruminants (PPR) or Newcastle diseases. Many of those diseases, exotic to developed countries, are endemic to developing countries. In addition, these countries have endemicity for other diseases, both infectious, such as brucellosis, tuberculosis, hemoparasites, gastrointestinal helminthiasis, etc., and non-infectious, many of which are referred to as “production diseases” since are typically associated with intensive production. This latter group includes metabolic disorders (e.g. hypocalcemia, ketosis, etc.), abomasum displacement, laminitis, prolapses, dystocia, etc. Metritis and mastitis can also be considered part of this group (Sundrum, 2015). While infectious diseases are more associated with deficient biosecurity or poor disease transmission control (e.g. vaccination and medical treatment), production diseases are more related to husbandry practices.
As an example of the introduction of a TAD, the Foot-and-mouth disease (FMD) outbreak in the United Kingdom in 2001 caused a crisis in British agriculture and tourism. Over 10 million sheep and cattle were killed with the intention of controlling the spread of the disease, and public rights of way across land were closed by order. By the time the disease was halted in October 2001, the crisis was estimated to have cost the United Kingdom US$16 billion. A more recent FMD outbreak in Colombia in 2017 caused major decreases in exports, from US$3.7 million and 844 tons in November 2017 to US$1.4 million and 316 tons in the same month of 2018, a 64 percent drop in value and 62 percent drop in volume (Agronegocios, 2019). Another important TAD is African swine fever (ASF), which has been responsible for serious production and economic losses affecting domestic and wild pigs. Since its discovery in August 2018, ASF has spread to every province in mainland China. With ASF affecting an estimated 150-200 million pigs as of February 2020, simulation with the expected 30 percent loss in pork production suggests a reduction of Chinese GDP by approximately 1 percent (Mason et al, 2020). It continues to be a serious and highly contagious disease, easily transmitted through direct or indirect contact. The disease can devastate pig populations and trade, and outbreaks remain difficult to control (OIE, 2018), affecting the livelihoods of millions of pig producers.
Peste des petits ruminants is another highly contagious viral disease that mainly affects sheep and goats. Heavy losses can be seen, especially in goats, with morbidity and mortality rates sometimes approaching 80-100 percent (OIE, 2008). A study from 2017 showed that expected annual economic loss due to PPR in India, where the disease is endemic, ranges from as little as US$2 million to US$18 million and may go up to US$1.5 billion. (Govindaraj et al. 2016). PPR causes an estimated US$1.45 billion to US$2.1 billion in worldwide economic losses each year, due to reduced production, animal deaths and the cost of caring for sick animals, including vaccination. Almost half of these losses are in Africa, with a further quarter in South Asia (OIE and FAO, 2015).
There have been several attempts to estimate the impact of endemic diseases, but these are context-specific and depend on the diseases present in the area, the intensification of the production system, availability of veterinary services, farm size and level of technification. We have examples of tropical countries in the Americas which, due to their relative isolation in the animal trade, are free from most of the major transboundary diseases and even others such as bovine tuberculosis and brucellosis. In these places, tropical hemoparasites and other production diseases are considered to be of greater importance.
On the other extreme there are many African and Asian countries in which FMD is endemic that are often affected by highly pathogenic avian influenza, and where production diseases might be neglected as a national priority.
In many of those countries, infectious diseases such as contagious bovine pleuropneumonia, East Coast fever, FMD, hemorrhagic septicemia, helminthiasis and trypanosomiasis are regarded as the most important for now, however, as more intensive farming systems are implemented, the production diseases start to gain more relevance. Although disease burden figures will vary largely among countries there are some overall estimations on the incidence: clinical mastitis could range from 1.7 to 54.6 percent (Sundrum, 2015), and the costs associated with premature culling due to this condition could amount to of 28 percent of production costs (Heikkila et al., 2012). Lameness, another metabolic disorder associated with intensive dairy production, has an incidence from 1.8 to 54.6 percent (Sundrum, 2015). Milk yield reduction associated with his pathology can start four months before the lameness is evident and last for up to five months after treatment, leading to a mean 360 kg of reduction in milk yield per lactation (Green et al., 2002).
Prevention, preparedness, control and eradication of animal diseases are critical for ensuring food security in any development project involving livestock. It is also worth mentioning that the benefit of the investment in animal disease control is going to generate synergies. Thus, the impact of the any strategy implemented that aims to reduce production diseases, for example by using GAHPs, will impact the control of infectious diseases, and the zoonoses as mentioned in the FAO/OIE Good Farming Practices Guide (FAO and OIE, 2008) and described in Principles 3 and 5.
Points of Consideration
When a project involving livestock is going to be implemented in a country or subregion, it should include animal disease strategies that consider:
• Animal diseases and the One Health approach. When dealing with projects involving livestock and animal disease control, the One Health approach should be inherent. Thus, any intervention aiming at controlling animal diseases in the farm will also impact the control of the zoonoses present, contributing, thus, to a gain in animal health and public health. Moreover, the potential impact of livestock farming and animal disease control on the environment should not be neglected. This includes the impact on land use and deforestation due to grazing, the impact of carcass and animal byproduct disposal, and the release of medicaments and antimicrobials into the environment (Principle 6).
• Disease burden and impact. It is important to have a closer look at the diseases present and their relevance, utilizing available information on farmers’ perceptions, combined with local expert knowledge, since farmers tend to underestimate the impact of subclinical/chronic diseases. The prioritization of diseases should consider:
• Frequency and distribution in the country
• Current and potential economic impact
• Zoonotic importance
• Trade restrictions
• Capacity to confirm/identify disease-causing agents
• Feasibility of implementing successful control/eradication programs
• Animal management, nutrition and genetics. Substantial productivity and economic gains will not necessarily be achieved by disease control alone. Equally important are Good Animal Husbandry Practices (GAHPs), including those relating to feeding, provision of water, biosecurity and reproductive management programs. There are strong interactions between disease prevention and good animal management and substantial variation between countries and farms about what is the major bottleneck for improved productivity. Sometimes it is infectious diseases; sometimes poor reproductive management; and sometimes inferior genetics or low-quality feed, etc.
• Input services and products. Strategies that aim at increasing the availability of input services such as vaccines, prophylaxis treatment, clinical treatment, and others, are highly recommended, particularly to reach smallholder farmers and marginalized populations (Donadeu et al., 2019).
• Consideration of the environment. Species and breeds should be chosen according to their adaption to area-specific farming conditions, particularly in areas with difficult conditions such as drought, different altitudes, flooding, dramatic temperature changes, etc. Thus, in many developing countries with harsh pasture conditions, goats are chosen due their adaptive capacities (Silanikove, 2000). The ability of an animal to cope with environmental pressures can significantly impact upon its normal development, welfare and immunity, which would lead to reductions in productivity, increased susceptibility to sickness and might facilitate the spread of a disease across populations.
• Veterinary services. Development or access to good quality veterinary services is a key component for livestock projects to ensure strategies of prevention, preparedness, control, and eradication of animal diseases. Veterinary services must have a comprehensive structure and robust operability to ensure effectiveness. Along with this, they should have a legal framework to organize and establish rules for different actors or public and private entities involved in the system. The responsibilities of the health authority and its ability to enforce laws and standards should be evaluated in detail.
• Epidemiological surveillance. Epidemiological data gathered through information systems and epidemiological analyses will provide an overview of the animal health status of a territory. This information should be available and accessible so that it can be part of health surveillance work and used in decision-making to support the development of health strategies that contribute to establishing the local and national health status.
• Key practices to incentivize notification of diseases at farm level. Encourage the recording of disease events and production traits on paper or ideally in ad hoc databases and provide training on the use of recording tools and ready-to-use recording software (ideally for cellphones). This should be a key component of a broader traceability program and supported by legislation to compensate for animal culling.
• Effective laboratories and testing. The capacity of the official diagnostic laboratories and its private and international networks must be included in any animal disease strategy. Establishing the diagnostic capacity in terms of personnel, equipment and infrastructure is essential, as well as overall management that includes comprehensive quality assurance and quality control.
• Quarantine facilities. Imported live animals should be kept in quarantine on ad hoc premises for a period defined according to the risk of disease introduction and incubation period. This also applies when moving livestock from one part of the country to another. On-farm quarantine facilities or action plans should also exist to isolate potentially infected animals early on.
Approaches and Tools:
This principle is focused on enhancing farmers´ practices and strengthening veterinary services and to improve animal health, with strategies focused at the national, local or farm level.
Production diseases are often multifactorial and independent relationships among them must be established, so that direct and indirect causal associations, and incidental relationships can be differentiated. Control of production diseases often involves various disciplines and therefore calls for a "multivariate approach". Such an approach, centered on the herd, has led to the adaptation of integrated programs for herd health that are characterized by the adaptation of multidisciplinary, multifactorial, and a population approach to clinical entities. Preventive measures and routine examinations are the focus of programs, but greater inclusion of nutrition, production and economics is called for (Markusfeld, 2003).
When establishing a livestock project in a particular area, it is recommended to include capacity building activities to identify the presence of infectious and production diseases and acquire the capacity to control them. Disease control strategies may incur at different levels including at reservoir level, transmission level and at host level as mentioned in Principle 5 (Risk of Zoonosis). These should also be included in animal disease strategies. Moreover, the capacity building strategies focused on the farm level would require inputs from social science to be able to change farmer’s behavior, as some can be reluctant to change their habits even when potential advantages have been technically demonstrated. In fact, the production systems in used would have been chosen according to their affordability, so some farmers might be unwilling to make even small additional investments (Perry and Grace, 2009).
Veterinary services are provided by the working community that protects the health and welfare of animals. This consists of public and private sector veterinarians and associated staff responsible for preparing and enforcing the laws governing disease control, food safety and safeguarding biodiversity. To perform their duties satisfactorily, those providing veterinary services need to have specific tools, capacities and infrastructures that any investment needs consider. These include access to technology for epidemiological studies, accommodating the tools to the needs of the countries, sufficient diagnostic capacity and availability of quarantine facilities. In addition, any intervention that aims to strengthen veterinary services should also include capacity building activities that are based on risk assessment or international tools such as the OIE Performance of Veterinary Services (PVS) tool (OIE, 2019).
Workshops that combine theory and practical exercises should address basic epidemiological analyses and the use of accessible tools. This can strengthen of the capacity of countries through their veterinary services and help analyze their own health data, which contributes to informed decision making and risk analysis based on their epidemiological situation. Regarding the training, simulation exercises play a key role in the development and implementation of preparedness and response capacities at all levels (national, regional, community and global) and have been identified as a key component in the validation of core capacities under the International Health Regulations (IHR) monitoring and evaluation framework (2015). Aside from examining health issues within a constrained environment such as a single event, simulation exercise scenarios are being developed that reflect a more complex, real world, operational environment. This includes health events in natural disasters and complex emergencies and the role that health plays in wider emergency response.
Key factors for deciding on the implementation of a control program include the prevalence/incidence of the disease, the feasibility of any successful implementation given the country conditions and/or the assessment of the risk of reintroduction. It is essential to first know which diseases are present and their level of occurrence before designing and implementing any control program. The recommendation is for veterinary services to develop a risk matrix for each region in the country, including the risk of release and exposure to different exotic and endemic diseases. Its preparation should mainly consider animal movement, places of concentration of animals and present animal populations, identifying their production systems, their biosafety levels, and both public and private human capacities to support a strategy. This information will be the basis for developing the strategy and actions, including active and passive surveillance, and the following:
• Timely identification of the entry of exotic diseases
• Supporting the emergency response process when emergencies occur
• Assisting disease management programs
• Auditing health programs
• Providing guarantees to export and import processes
• Contributing to the knowledge of disease epidemiology
Variables to Consider
✓ Farm-level variables:
• Herd size
• Type of farm
• Food animal species involved
• Details of data capture at farm level for diseases and production traits
• Farm biosecurity
• Animal and feed sourcing
• Control use of drugs and antimicrobials (Principle 6)
✓ Local/national level of disease reporting/notification; suspicious cases ruled out versus those confirmed
• Number of veterinarians and veterinary paraprofessionals
• Veterinary drug suppliers
• Endemic diseases diagnosed
• Transboundary diseases present
• Population present (farm/animal register)
• Local/national disease information system utilized to support surveillance
• Local/national disease programs
• Local/national passive and active surveillance strategies
• Local/national laboratory capacity
• Level of epidemiological knowledge training within the local/national official veterinary services
• Animal movement tracing
• Prevention strategies at borders
• Emergency response preparedness and contingency plans
Trade-offs
Cost effective interventions: At farm-level, considerable costs may be incurred in controlling animal diseases, and sometimes the control measures chosen are not always the most cost effective. This is particularly true for smallholder farmers, who often lack of information on the appropriate measures and have limited diagnostic data to make disease control and treatment decisions. The overall impact of control measures may be constrained by noncompliance of a significant proportion of the community, which highlights the need for regulatory veterinary services supported by legislation and incentives to comply.
Synergic results: Any prevention and control program for animal diseases is likely to work best if it not only targets a single disease but generates a broader spectrum of benefits as farmers are usually dealing with multiple animal health problems and it is rare that one is consistently at the top of their priority list (FAO, 2016).
Environmental impact of animal diseases: Animal carcasses that are improperly disposed of (dead animals being dumped in rivers or improperly buried) due to the fear of consequences when declaring an outbreak can cause major pollution issues and health consequences. This is in addition to a high cost of proper disposal or inadequate financial compensation mechanisms for farmers that must have their animals culled during eradication programs or in response to emergencies related to transboundary diseases introduction. The improper disposal of carcasses can pollute water sources and drinking water, threatening the lives of both people and livestock. Also, the uncontrolled use of therapeutic drugs and antimicrobials can have an undesirable impact on the environment, as described in Principle 6.
Role of women: Women comprise approximately 70 percent of the world’s poor, as well as most poor livestock keepers. Poultry, pigs, and small ruminants are the livestock species usually preferred by women because they can be more easily managed, and in many instances, the income generated goes directly to them. Any intervention aimed at improving animal health in poultry, pigs, and small ruminants, such as vaccination is likely to provide benefits particularly to women small holder farmers (Donadeu et al., 2019).
Internationals status recognition: While obtaining international (e.g. OIE) free status recognition for a territory is overall conceived as an advantage due the aperture of certain international markets, there are also some handicaps that need to be acknowledged. For example, when an area within a country is declared a disease-free zone, certain farming practices are restricted, with strict constraints on movement of animals and livestock products into the zone. Thus, farmers or traders cannot access the grazing lands that they formerly used or move their animals into or across the zone to sell them.
Overall impact on smallholders: The livestock sector is dynamic – it changes with or without disease control – but if disease control measures speed up the changes in the sector, the people who may suffer most are poor farmers who need time to make changes to their livelihood activities (Donadeu et al., 2019). TADs control strategies result in long-term changes in the livestock sector structure. The strategies might include policies on where livestock can be kept and how they are managed, establishing minimal standards, movement controls that are routinely enforced even in the absence of disease outbreaks, and regulations on the operation of livestock markets. Over time, these factors create conditions that make some smallholders’ livestock enterprises illegal or unviable. The sector scales up and former small-scale producers lose a livelihood they once had.