ZOONOSES

ECONOMIC IMPACTS & PUBLIC HEALTH SIGNIFICANCE OF TRANSBOUNDARY ANIMAL DISEASES (TADs) : PREVENTION & CONTROL

April 4, 2023

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ECONOMIC IMPACTS & PUBLIC HEALTH SIGNIFICANCE OF TRANSBOUNDARY ANIMAL DISEASES (TADs) : PREVENTION & CONTROL

Transboundary Animal Diseases (TADs) may be defined as those epidemic diseases which are highly contagious or transmissible and have the potential for very rapid spread, irrespective of national borders, causing serious socio-economic and possibly public health consequences. These diseases cause a high morbidity and mortality in susceptible animal populations and remain a constant threat to the livelihood of livestock owners. Furthermore, their potential consequences are of such a magnitude that their occurrence may also have a significant detrimental effect on national economy. The impact of TADs serves not only to reduce production directly but it also inhibits investment in stock of higher productive potential and enhanced production systems. For poor farmers, the risk of losses from TADs is too high to risk the venture.
The consequences of the introduction into a country of an infectious disease or animal pathogen or its new strain from which it is currently free, are potentially very furious. This is because animal health, the agricultural economy and trade may all be adversely affected to a greater extent. The animal disease status of a country or territory is part of its basic livestock infrastructure. The presence of transboundary animal diseases like FMD, PPR, HS, Swine fever, HPAI, etc. poses a strong threat to domestic and foreign investment in this sector. Therefore, the distinction between countries or regions recognized as free from a particular disease (e.g. HS or FMD) and not free from that pathogens largely defines world trade flows in milk, meat, egg and other livestock products.

Transboundary animal diseases (TADs) are epidemic diseases that are highly contagious and have the potential to rapidly spread, irrespective of borders, causing serious socio-economic damage. TADs can disrupt or hinder domestic production and sales and international trade of livestock and livestock products. The prevention and control of TADs therefore is a key factor for increasing market access and facilitating trade, particularly for Asian countries. Trans-boundary livestock diseases are those that are of significant economic, trade and/or food security importance for a considerable number of countries; which can easily spread to other countries and reach epidemic proportions; and where control/management, including exclusion, requires co-operation between several countries. Trans-boundary diseases are highly contagious and have the potential for rapid spread, irrespective of national borders, causing serious socioeconomic consequences. All trans-boundaryanimal diseases have the potential to kill affectedanimals, but the severity of the disease will varydepending on factors such as species and breed of animal, age, nutrition, disease agent etc. Many TADs have 50 to 90 percent mortality rates in susceptible animals (Otte et al., 2004). Traditionally, trade, traffic and travel have been instruments of disease spread. Now, changing climate across the globe is adding to the misery. Climate change is creating new ecological platform for the entry and establishment of pests and diseases from one geographical region to another (FAO, 2008). Several new trans boundary diseases emerge, and old diseases reemerge, exhibiting increased chances for unexpected spread to new regions, often over great distances. Livestock enterprises and animal production contribute significantly to the world economy, provide household source of income, food security, source of energy, draft power for crop cultivation, high quality animal proteins and vitamins (meat, milk), manure, raw materials (hides and skins) and bride price (Bonnet et al., 2011), and generate a livelihood for 1.0 billion poor people in the world (Naqvi and Sejian, 2011). Zoonotic diseases among TAD’s include diseases like West Nile virus (WNV), Rift Valley fever (RVF), Mad Cow Disease (MCD), bovine tuberculosis, and highly pathogenic avian influenza (HPAI). Other important TADs are foot and mouth disease (FMD),contagious bovine pleuropneumonia (CBPP), lumpy skin disease (LSD), African swine fever (ASF) and Newcastle disease (ND). They have the potential for very rapid spread, irrespective of national borders and these diseases can cause serious socio-economic and possibly public health consequences (FAO, 1999). From a considerable number of countries trans- boundary animal disease spread to other countries and reach epidemic proportions where control and management requires cooperation between several countries (Otte et al., 2004). They cause most serious impact on animal and human livelihood as these have the potential to threaten food security, proper livelihood of livestock owners & workers and rural economy which in certain instances could lead to political and social unrest in people. Due to the global distribution and persistence of TADs world animal agriculture, food security and international trade are being very badly affected (Domenech et al., 2006). Trans-boundary animal diseases have a multi casual origin; some factors associated with this process include: Trade and international travel (increased frequency and speed of local and international travel, fostered by the globalization process promotes the spread of microorganisms on a global scale), changes of agricultural practices (animal domestication was one of the main promoters of microbial evolution by facilitating the availability of new susceptible hosts at high densities, due to the intensification of livestocksystems), climate change (which causes changes ineco-geographical distribution of vectors), reduction of habitat and increased contact with wild animals andintroduction of immature wild and domestic animals tonew geographic areas where the disease is endemic and immunologically unknown for them.

Trans-boundary livestock diseases are those that are of significant economic, trade and/or food securityimportance for a considerable number of countries; which can easily spread to other countries and reachepidemic proportions; and where control/management, including exclusion, requires co-operation betweenseveral countries. Trans-boundary diseases are highlycontagious and have the potential for rapid spread, irrespective of national borders, causing serious socioeconomic consequences. All trans-boundaryanimal diseases have the potential to kill affectedanimals, but the severity of the disease will varydepending on factors such as species and breed of animal, age, nutrition, disease agent etc. Many TADs have 50 to 90 percent mortality rates in susceptible animals (Otte et al., 2004). A characteristic of trans-boundary animal diseases (TADs) is that they themselves can be the cause of national emergencies and their significance oftentranscends national boundaries. They are particular importance to food security and sustained economic development and trade for many countries. TADs are economic importance non tariffs barriers to the export of animals and their products. They are highlycontagious and feared diseases of livestock in the world and of economic importance and a major constraint in international trade (Otte et al., 2004). Several infectious zoonotic diseases have recentlyemerged, causing devastating economic losses in the countries affected. These have a wide ranging impact on the livelihoods of farmers, and on regional and international trade, food safety, public health and international travel and tourism. Disease pathogens continue to evolve and adapt themselves to animals and humans alike. Disease investigation indicates that many of these new diseases emerge in response to number of critical factors, such as changes in climate, ecosystems, animal production systems and land use, all of which alter the interactions between pathogens and various hosts thus the number of developed countries have been declared free from these diseases and they prevent introduction of the diseases to their countries by banning imports from infected developing countries due to the unrestricted importation of animals from infected countries and poor veterinary services (FAO, 2002).

Office International Des Epizooties lists trans-boundary animal disease

The World Trade Organization as the international reference body in the field of animal diseases and zoonoses recognizes the World Animal HealthOrganization (OIE). OIE lists diseases that are considered to be of such significance because of their impact on animal populations, ability to spread andthreat to human health that the Veterinary Authorities of member countries are required to notify OIE about changes to the situation regarding these diseases in the country (FAO, 2004). OIE listed diseases were formally classified into list Aand B where the list A diseases are similar bydefinition to TADs. OIE list A diseases are transmissible diseases that have the potential for veryserious and rapid spread, irrespective of national borders, that are of serious socio-economic or public health consequence and that are of major importance in the international trade of animals and animal products. Some of the most important trans-boundarydiseases are: FMD, ASF, CBPP, RVF, avian influenza (AI), ND, Classical swine fever (CSF) and Peste des petits ruminants (PPR) (Otte et al., 2004; FAO/OIE, 2004).

Distribution of major trans-boundary animal disease in the world

TADs are easily transmitted from one country to another, due to the rapid globalization including the increase of international trade in domestic and wild animals and animal products, to the expansion of human population, global climate changes, changes of agricultural production systems, and to microbiological adaptation. The common ways of introduction of animal diseases to a new geographical location are through entry of live diseased animals and contaminated animal products. Other introductions result from the importation of contaminated biological products such as vaccines or germ plasm or via entry of infected people (in case of zoonotic diseases). Even migration of animals and birds, or natural spreading by insect vectors or wind currents, could also spread diseases across geographical borders (FAO, 2008). International trade in live animals and animal products offers opportunities for pathogens and vectors to be transported across oceans and continents. However, with the exception of a few documented examples, such as, the multiplicity of routes of introduction, including active and passive dispersal of vectors, infected human , animal movements and migration, transportation of goods and biological invasions such as, introduction, initial dispersal, establishment and spread, the specific contribution of globalization to disease emergence is inherently difficult to quantify (Lanciot et al.,2004).

Prevention and control of TADs

The primary goals of any control programme against trans-boundary disease are to establish the ‘optimal’ level of disease presence to meet a country’s goals, and then choose the most cost-effective way toachieve that level of control. For instance, a policy of disease freedom is a high standard that can impose significant costs on a country. The ‘optimal’ level of control can vary from one country to another, depending on the results of analysis and will change over time as production systems and control options evolve. The primary responsibility to control the spread of animal disease belongs to both the countryof origin and the receiving country. Both face burdenof elaborate quarantine systems, as well as a risk of production losses and worse if introductions occur. The majority of control measures are aimed at preventing the entry and/or spread of a disease agent when a human action such as trade or travel or natural contagion can carry an organism into a previouslyunaffected location (McLeod and Leslie , 2000). Prevention is the best policy for avoiding the occurrence of disease whenever and wherever this is possible. However, some diseases do not have reliable means of preventing as their mode of transmission andspread is either unknown or difficult to control. Although there is apparent control and check for International Animal Health Certificate andInternational Sanitary Certificate at legal entry points for avoiding the incursion of exotic diseases, the possibility of clandestine entry of animals and animal products across the long borders of the country cannot, at least at the moment, be guaranteed as border control for TADs is also not very strong in this large countrywith rugged terrain (Domenech et al., 2006). When control of animal movement is used as one of the arms of an effective control of TADs, it should be implemented in a very careful and strict manner .The major arm of disease prevention and control inEthiopia for some time to come, therefore, is applyingquarantine measures whenever a TAD of internal or external origin is detected and ringimmunization/vaccination supported by other sanitaryand bio-security measures, implying the necessity of emergency planning and preparedness for tacklingsuch events. The National Veterinary Institute (NVI) is, therefore, responsible for producing most of vaccines for animal diseases required for anyemergency and for regular local consumption and has the capacity for producing surplus for export (EAHY, 2010). Disease control in Ethiopia is also dominated by prophylaxis, but chemoprophylaxis and chemotherapy have wider roles. While selected diseases are planned and coordinated by the Federal Government with collaboration and support of Regional Authorities, the bulk of animal disease and other animal health problem control activities are performed by local public veterinary clinics with nationally planned and executed disease control activities (Gulima, 2010).

Challenges in dealing with TAD

TADs are permanent threat for livestock keepers. They have major economic implications: both through the private and public costs of the outbreak, and through the cost of the measures taken at individual, collective and international levels in order to prevent or control infection and disease outbreaks. Several challenges confront the strategies to combat TADs (FAO, 2008; Hitchcock et al., 2007). The major ones are presented below: § Requirement of novel systems having capacity of real-time surveillance of emerging diseases For this, need driven research and service oriented scientific technology are a necessary at regional levels.Research emphasis has to be on specific detection and identification of the infectious agents; § Need for epidemiological methods to assess the dynamics of infections in the self and neighboring countries/regions. These methods should be of realtime utility; § Need for research and development of disease diagnostic reagents those do not need refrigeration (cold chain). More importantly, they should be readily available as well as affordable, for use in pen-side test format; § There are many diseases for which there is inadequate supply of vaccines or there are no vaccines available. Insufficient or lack of vaccine hampers the disease control programs. Need to build up vaccine banks for stockpiling the important vaccines to implement timely vaccination; § Required availability of cost-effective intervention or disease control strategies. Even if a technology is available, it has to be cheaper to adopt at the point of use; § Need for ensuring public awareness of epidemic animal diseases. Many farmers are unaware of the emerging diseases. As such, unless reported to concerned regional authority, an emerging disease may go unnoticed; § Shortage of government and private fundingfor research on emerging animal disease problems. Government as well as industries dealing with animal health should take initiative and appropriate sponsorship in this regard, and; § Inadequate regulatory standards for safe international trade of livestock and livestockproducts.Otherwise, there would be a compromisedsituation in disease control strategies.

Trade and economic impacts of trans-boundary animal disease

TADs impose major social and economic costs and risks to infected countries, their neighbors, and trading partners. The varying impact of TADs among stakeholders and the threat to existing and potential trade in wealthier countries complicates the question of appropriate control. For all livestock producers, the threat of TADs increases the risk of lost production and impacts on livelihood, increasing vulnerability to poverty particularly for small-scale producers. Foot and Mouth Disease (FMD) is one of the major endemic trans-boundary livestock diseases of socio- economic importance in Ethiopia and in other parts of the globe. The impact of foot and mouth disease (FMD) in Asia in 1996 in terms of loss of feed sales alone has been estimated at more than USD 500 million; persistent contagious bovine pleuropneumonia and African swine fever continue tocause high economic damage to ruminant producers inSub-Saharan Africa. The impact of TADs and of their control varies depending on the pathogenicity of disease, number of animals at risk, dependency onlivestock for livelihood, and method of control (Otte et al., 2004). The socio-economic significance of PPR is a result of heavy losses at production level and market effects along the value chain. It is estimated that 10% of the total impact of the disease is on trade and public expenditure and 90% on herd productivity (DFID, 2001-2002).

Economic impacts

Trans-boundary animal diseases (TADs) cause significant economic losses throughout the world. But producers in less developed countries (LDCs) are at particular risk because livestock provide not only income and an asset base, but also food, draught power and various social functions (Rich and Perry, 2011). Trans-boundary diseases threaten food security, affect livelihoods of rural communities and disrupt local and international trade (Otte et al., 2004). As a result of the emergence and re-emergence of various animal diseases, such as bovine spongiform encephalopathy (BSE), the annual growth of meat products decreased 2% in the late 1990s (Morgan and Prakash, 2006). Therefore, the cost of trans-boundary animal diseases relates to agricultural products, to the country’s economy and international markets are massive. Thus, it is very important to create public policies focused to assure countries’ food security (especially in developing nations) to avoid negative economic impacts caused by TADs, especially on the more susceptible social stratus. The World Bank has estimated that zoonotic disease outbreaks in the past 10 years have cost worldwide more than $US200 billion due to loss of trade, tourism and tax revenues (Okello et al., 2011). Pests and animal diseases cause the loss of more than 40% in the global food supply, being a clear threat to the residual economies of developing countries and food security of its inhabitants (FAO, 2009). Many economic impacts are difficult to quantify, and valuation also may be problematic. Such factors as animal welfare, human health, and the environment are of obvious importance, but do not have market values, and different people have different perceptions of their value. It is therefore impossible to provide objective assessments of the total cost of most animal diseases, especially the most serious ones that have wide-ranging effects. But the cost of animal disease can be enormous (Paarlberg et al., 2007).

Public health significance

Nearly 75% of infectious human diseases had their origins in animals. Many of them have adapted in humans with efficient human to human transmission, while others still remained zoonotic with frequent transmission from animals to humans. Such zoonotic transmission of diseases have increased in recent years, perhaps due to increasingly intensive livestock production in areas of proximity to human populations and loss of habitats of wildlife. Most of these are considered as emerging pandemic threat. An emergingzoonotic disease may affect humans accidentally andsporadically, but also may adapt sufficiently to humanhost to cause a deadly epidemic or pandemic in the immature human host population (Anand and Hanson, 2006). Apart from public health concern the economic consequence of a human pandemic could be huge. Public health authorities in industrialized countries have been faced with an increasing number of foodsafety problems. The situation is equally serious indeveloping countries. In addition to known food-borne diseases, public health communities are beingchallenged by the emergence of new or newlyrecognized types of food-borne illnesses, often withserious health and economic consequences (Cutler et al.,2010). The exports of smuggled wildlife products andderivatives have an alarming effect on the introductionof many trans-boundary diseases, also affecting humanbeings and the entire ecosystem. Among these, the diseases of viral and prion origins like Avian flu andmonkey pox are prominent having tremendous zoonotic potential. The disability-adjusted life years (DALYs) is a measure of overall disease burden, expressed as the number of years lost due to ill-health, disability or early death. Infectious diseases also leadto compromised health and disability, accounting for nearly 30% of all DALYs worldwide (Fauci et al., 2005).