AusVet Animal Health Services,
PO Box 3180, South Brisbane
Queensland 4101, Australia
Baldock, C. 2002. Health management issues in the rural livestock sector: useful lessons for consideration when formulating programmes on health management in rural, small-scale aquaculture for livelihood. p. 7-19. In: J.R. Arthur, M.J. Phillips, R.P. Subasinghe, M.B. Reantaso and I.H. MacRae. (eds.) Primary Aquatic Animal Health Care in Rural, Small-scale, Aquaculture Development. FAO Fish. Tech. Pap. No. 406.
There are many similarities between smallholder livestock and aquaculture systems where application of the same principles of health management will result in similar outcomes. Thus, it would seem appropriate that lessons learned from the livestock sector should be applied to aquaculture and vice versa. However, improving prevention and control of disease can only result from a clear understanding of what causes different disease syndromes and their epidemiology. Without this knowledge, little real progress can be made. For example, detailed epidemiological studies in northern Thailand identified three major reasons why some villages, and not others, had a problem with a particular livestock health problem known as foot and mouth disease. Once this was known, appropriate government control strategies and extension advice could be designed, applied and monitored. Controlling disease at the farm and village level extends to national programmes, whether they are for general disease surveillance or specific disease control initiatives. The basis of sound disease control programmes is good information about the diseases that are present. This can only be obtained through the combination of competent diagnosis, well-designed disease reporting systems and specific field surveys and other studies. In the livestock sector, information technology is being increasingly used to assist in the management and analysis of data. However, the primary constraint still lies in the quality of basic data collected from farms and villages and how representative it is.
Throughout Asia, there are various levels of capability of governments to improve
the health of animals in the smallholder sector, resulting in improved production
and increased trade. In some countries, such as the Philippines and Lao PDR,
responsibilities for livestock and aquatic animal health lie in the same governmental
department. In such instances, excellent opportunities exist to share experiences,
expertise and resources. In some Asian countries, livestock health surveillance
and control systems for smallholders are quite well developed. Where possible,
advantage should be taken of this situation for improving aquatic animal health
management.
There is now increasing pressure on governments to provide better quality information
on the health status of livestock and aquatic animals. This will become increasingly
important over the coming decade for those countries that export aquatic animal
products, particularly live animals, as well as chilled and frozen product.
The International Aquatic Animal Health Code of the Office International
des Épizooties provides a guide to how surveillance should be undertaken
and disease occurrences reported. Basic surveillance and reporting systems to
meet international obligations can be put in place at little cost, with improvements
to the system coming as resources and capabilities improve. For example, in
the Philippines, all the reporting needs for the national foot and mouth disease
eradication programme are handled by a relatively simple database that has the
capacity to quickly produce both tabular and map-based reports. The challenge
for different countries will be to efficiently implement low-cost systems that
are effective in addressing the goals of the various levels of government, as
well as meeting international reporting obligations.
Some constraints specific to aquaculture (and in some instances, fisheries also) will mean that disease surveillance and control systems will be different from those in livestock. For example, sick and dead animals are more difficult to detect, there are fewer diagnostic tests available, and sampling from aquatic animal populations is more difficult than from livestock. Such constraints pose unique challenges, and solutions will not always be easily found.
There are many similarities between smallholder livestock and aquaculture systems where application of the same principles of health management will result in similar outcomes. This is particularly true for the more intensive livestock systems, where increasing stocking densities combined with commercial pressures to continually make production efficiency gains have lead to increasing problems with infectious disease. A good example is the poultry industry.
Through to the early 1960s in Australia, small, owner-operated farms dominated
this industry, often with many aspects of the production cycle, such as breeding,
hatching and growing, carried out on the one farm, with family members providing
most of the labour. As profit margins came under pressure, outputs increased,
with consequential increases in production stresses. Some diseases, which were
previously not a concern, began to show more severe manifestations, and costs
of control using antibiotics and disinfectants rose. This was not sustainable,
and management solutions were eventually required. This led to a total restructuring
of the chicken meat industry: "multi-age" farms were replaced by "all-in
all-out" farms, where a single batch of chickens is raised, the farm totally
depopulated, cleaning and disinfection undertaken to reduce the microbial load
and then the next batch of chickens introduced. More recently, consumer concerns
for animal welfare have led to new pressures on the poultry industry to reduce
stocking densities and provide more natural housing conditions. A secondary
consequence may well be an improvement in poultry health.
Global production from aquaculture is presently estimated to be increasing
at approximately 13% per year. If this rate is sustained, production will double
every six years. Additionally, the increases are not uniform and thus, in some
countries, growth may be a lot higher than in others. In simple terms, this
phenomenon of rapid growth means more susceptible hosts will be available for
pathogens to infect, as well as more farms with less distance between them and
possibly higher stocking densities. It follows that there are likely to be more
disease problems, and the spread of epidemic diseases will be much more rapid,
with potentially more devastating impacts, both on commercial and small-scale
farmers. It would be wise to plan for this situation rather than respond once
it happens.
In this paper, current issues from the livestock sector are outlined and consideration
is given to how these might apply to the rural small-scale aquaculture sector.
In developing countries throughout the Asian Region, the percentage of the population that is involved in agriculture ranges from 50-90% (FAO 1999). In these countries, 10-20% of gross domestic product (GDP) is derived from livestock, and small-scale producers raise 60-90% of the livestock. The annual increase in production ranges from 1 to 2.5% (Delgado et al. 1999). Thus, the small-scale livestock sector plays a vital role in the economy of the Asian Region and provides an important component of the livelihood of many people, particularly the rural poor.
In farming systems, the obvious primary unit of interest to support services such as government agencies, is the individual farmer. This is particularly so for the small-scale farmer, who is responsible for virtually everything associated with his or her animals, including their health. If the individual farmer does not have the relevant knowledge, skills, resources and willingness, then the health of the animals will be at risk. In some cases, where factors beyond the control of the individual farmer, such as floods and drought, impact on the health of the animals, even this is insufficient. However, government and other sources of assistance often operate with groups of farmers, rather than individuals, as this is seen as a more effective use of resources. A useful first level of aggregation of individual farmers is the village. Plans and decisions on livestock disease surveillance and control programs involving the small-scale livestock sector often use the village as the main unit of interest, under the assumption that the animal health status among farms within the village will be more similar than between villages. In this instance, a village comprises families of people, some of whom raise livestock. A village group of livestock is, therefore, analogous to a "farm" in the commercial sector. There are a number of further hierarchical levels of administrative aggregation at which risks for animal health occur and disease surveillance and control measures may be applied. This hierarchical order of aggregation is represented in Box 1. Of course, different countries use different names for the different levels, and sometimes, there are additional levels, such as regions.
International spread of disease impacts not only on the commercial livestock
sector, but also on small-scale farmers. Globalisation means that the world
is effectively becoming a smaller place in the face of continually expanding
volumes of world trade, including livestock commodities. Such commodities are
transported rapidly over large distances; genetic material is more accessible,
with new breeds and species being introduced to different countries according
to perceived needs; and animal health information is disseminated rapidly with
equally rapid quarantine responses. To assist in managing these issues, we have
seen the emergence of the World Trade Organization (WTO) as an important body
responsible for the administration of a number of multilateral agreements, such
as the General Agreement on Tariffs and Trade (GATT), Agreement on Agriculture
and the Agreement on Sanitary and Phytosanitary Measures (SPS Agreement). These
are meant to provide a framework to facilitate trade, while providing mechanisms
to reduce risks associated with freer trade. In the case of livestock commodities,
one of the greatest risks is an increase in the international spread of disease.
The SPS Agreement provides core principles while the International Animal Health
Code of the OIE (see OIE 2000) provides standards for management of these risks.
In recognising the international spread of disease as one of the potentially
greatest downsides in the emerging changes to world trade, the Animal Health
Service of the Food and Agriculture Organization (FAO) of the United Nations
has consolidated its activities under EMPRES (Emergency Prevention System for
Animal and Plant Pests and Diseases). The livestock component of EMPRES is known
as EMPRES-Livestock. The purpose of EMPRES-Livestock is to promote the effective
containment and control of the most serious epidemic livestock diseases-TADs
(Trans-boundary Animal Diseases). These diseases, which include rinderpest,
foot and mouth disease and Newcastle disease have their greatest impact on rural
small-scale farmers in developing countries - the group least able to prevent
and control such diseases.
Recent major livestock disease calamities, such as "mMad cCow" disease
in the United Kingdom, Nipah virus in Malaysia and regular reports of food-borne
illness, are resulting in greater consumer pressures for guarantees of "safe"
livestock products. This has strengthened the move to on-farm, HACCP-based management
of livestock, supported by accreditation of participants and audit systems to
monitor compliance. There has also been a shift of some resources from disease
control programmes to improved disease surveillance, where this is seen to be
a better use of limited resources to safeguard consumer interests. For example,
a new chapter of the OIE International Animal Health Code (OIE 2000] provides
quite detailed specifications for national surveillance programmes for "Mad
Cow" disease. The European Union requires that countries from which they
import meat must comply with these specifications or face cancellation of trade
agreements.
In some countries such as Australia and New Zealand, government inputs into
livestock disease surveillance and control are rapidly diminishing, with livestock
industries expected to take more responsibility for their own problems. This
is mainly because of reallocation of resources into more pressing areas, such
as public health, education and welfare. It is interesting to note that this
comes at a time when the need for animal health resources appears to be increasing.
With these cost burdens now carried directly by livestock industries, trade
competitiveness can be put at risk. In other countries, direct government assistance
to small-scale farmers has been reduced. For example, in Zimbabwe, it was traditional
that the government organised and met the cost of treating smallholder cattle
for external parasites, many of which transmit serious, production-limiting
diseases. This service has largely been dismantled, placing a vulnerable group
at increased risk of substantial damage to their livelihood.
In an attempt to contain costs, a more business-like approach to the prevention
and control of livestock diseases is beginning to emerge in some countries.
This involves clearly identifying high priority areas for attention, using targeted
research and development to help solve problems and implementing routine programs
within the framework of a business plan. For this to occur, high quality information
on the occurrence, epidemiology and impact of disease is required.
In addition, more outsourcing of services is being undertaken based on competitive
tendering. For example, in the State of Victoria in Australia, outsourcing to
private laboratories, rather than undertaking the work in government laboratories
has halved the cost of some routine serological tests. In New Zealand, some
extension services that were formerly provided by government at no charge to
farmers have been privatised and now operate on a fee-for-service basis.
In the Philippines, there is a national programme for the eradication of foot
and mouth disease, which mainly affects pigs in that country. Careful monitoring
of progress, and targeted research, have led to considerable cost savings and
more rapid progress than would otherwise have been achievable. This is directly
benefiting small-scale farmers, who are the ones most impacted upon by the disease.
In Thailand, the same disease mainly affects cattle and buffalo. In this case,
targeted research led to the identification of the three most important risk
factors for disease outbreaks in smallholder herds. This has permitted development
of both regulatory and extension services most likely to deliver effective outcomes.
In addition, well-designed serological surveillance has enhanced the effectiveness
of the national vaccination programme.
Animal welfare is emerging as a major issue, with growing impacts on livestock management practices. Livestock production in some countries must now comply with quite detailed animal welfare codes. For example, one consequence is the gradual disappearance, in some countries, of caged systems for laying hens. Although adding to the cost of production, such an initiative may result in substantial benefits for poultry health, but this has not yet been properly evaluated.
Because of their seriousness (see Box 2) and the current FAO focus on their
containment, it is worthwhile specifically discussing TADs as examples of the
risks and impacts of diseases on livestock systems. Most TADs impact mainly
on small-scale farmers, particularly the rural poor in developing countries.
The following discussion is taken from an FAO paper by Baldock et al. (1999).
All animal diseases have the potential to adversely affect human populations
by reducing the quantity and/or quality of food, other livestock products (hides,
skins, fibres) and animal power (traction, transport) that can be obtained from
a given quantity of resources and by reducing peoples' assets. Of these, trans-boundary
animal diseases tend to have the most serious consequences.
Trans-boundary animal diseases 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 are diseases that cause a high morbidity and mortality in susceptible animal populations and they constitute a constant threat to the livelihood of livestock farmers. Furthermore, their potential consequences are of such a magnitude that their occurrence may also have a significant detrimental effect on national economies.
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Box 2. Examples of the consequences of trans-boundary animal diseases.
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Trans-boundary animal diseases have the potential to:
Trans-boundary animal diseases constitute only a small minority of the infectious
diseases that afflict livestock. All of the infectious diseases cause some of
the above adverse socio-economic consequences to a greater or lesser extent,
and in fact, the cumulative production and economic losses that they cause are
probably much greater than that of the so-called trans-boundary animal diseases.
However, what sets the trans-boundary diseases apart is the suddenness, acuteness
and widespread nature of the losses that they can produce.
Another important characterising feature of trans-boundary animal diseases
is the rapidity with which they can spread in susceptible livestock populations.
This renders individual farmers and private veterinary services relatively powerless
to take effective action to avoid or overcome outbreaks of these diseases. The
responsibility for prevention, control and elimination of trans-boundary animal
diseases, therefore, falls squarely on the shoulders of the public sector, notably
government veterinary services, and may require high public investment. Furthermore,
these endeavours are only likely to be successful if government veterinary services
are very well organised and prepared for these tasks.
As their name implies, trans-boundary animal diseases are no respecters of national or administrative borders. The control efforts of individual countries against these diseases may be continually frustrated by the fact that neighbouring countries are not taking equivalent action. Trans-boundary animal diseases, therefore, need to be tackled on a regional basis, with co-operation between countries and harmonisation of their prevention and response programmes. An international approach also allows better advantage to be taken of natural geographical barriers and broader epidemiological patterns for the diseases.
Viruses cause many trans-boundary animal diseases. Important viral diseases
include:
Foot-and-mouth disease (FMD). FMD is perhaps the most contagious disease
of animals, affecting mainly cattle, sheep and pigs. Although not generally
a killing disease, it causes high morbidity and production losses, and is a
major impediment to international trade in livestock and livestock products.
The disease has been absent from southeastern Europe for over two years, and
from the rest of Europe for much longer. Considerable progress has been made
towards eradication in South America, with the southern countries of Chile,
Argentina, Paraguay and Uruguay not having recorded outbreaks for two years
or longer, and the southern states of Santa Catarina and Rio Grande do Sul having
been declared "FMD free with vaccination." FMD is still endemic in
many parts of Africa, the Middle East and Asia, but a regional control programme
is in place in Southeast Asia.
Rinderpest (RP). RP is a generalised viral disease affecting mainly
cattle and buffaloes. It usually causes a very high mortality, although less
virulent strains circulating in East Africa have complicated eradication there.
RP has been progressively eliminated in West Africa, but there are still three
endemic foci in East Africa. Great progress has been made towards RP eradication
in India, but the disease is endemic in Pakistan and has spread to Afghanistan.
There are endemic foci in the Middle East. Sporadic outbreaks, the origins of
which are unknown, have occurred in eastern Russia and Mongolia in recent years.
Peste des petits ruminants (PPR). PPR is a rinderpest-like disease of
sheep and goats. In recent years, there has been serious spread of this disease
from Africa to the Middle East, and in Asia as far east as India.
Rift Valley fever (RVF). RVF is a serious mosquito-borne viral disease
of sheep, cattle and goats which causes very high mortality rates in young animals
and abortion in pregnant animals. It is also transmitted to humans, causing
a potentially fatal disease. Major epidemics have occurred at irregular intervals
of 10-30 years in the eastern half of Africa, from South Africa to Egypt.
Lumpy skin disease (LSD). LSD is a disease of cattle that may cause
serious production losses, through prolonged debility and loss of hides. LSD
is mainly confined to Africa, where it has caused periodic, major epidemics
in many countries.
Classical swine fever (CSF). CSF is a generalised viral disease of pigs
that may cause high mortalities. It is endemic in much of South and Southeast
Asia, where it is a constraint to the development of the pig industry. It is
the most significant trans-boundary animal disease in Europe, where it caused
611 outbreaks in the European Community in 1997. These occurred in the Netherlands,
Germany, Spain and Italy and are estimated to have cost these countries more
than $7 billion. Recent outbreaks have also occurred in Latin America.
African swine fever (ASF). ASF is another generalised viral disease
of pigs that is endemic in much of sub-Saharan Africa. There have been very
serious outbreaks over the last few years in previously free areas of West Africa.
ASF has shown great propensity for inter-continental spread, and outbreaks have
occurred at different times in parts of Europe and Latin America.
Newcastle disease (ND). ND is a viral condition that is perhaps the
most lethal disease of poultry. Outbreaks of ND have occurred in most parts
of the world, including two major pandemics during this century. It is a major
constraint to the development of village chicken industries, particularly in
Asia and Africa.
Highly pathogenic avian influenza (HPAI). HPAI is another serious viral
disease of poultry that may produce high mortalities. There is some concern
about the potential for the appearance of avian influenza strains transmittable
to humans following recent cases in Hong Kong. Wild water birds constitute the
major reservoir for avian influenza viruses, and HPAI outbreaks in domestic
poultry may occur suddenly anywhere in the world. There have been a number of
outbreaks in recent years in North America and Australia.
There is one important mycoplasmal trans-boundary animal disease. This is contagious
bovine pleuropneumonia (CBPP). Although this is an insidious disease in areas
where it is well established, it causes serious epidemics with high mortality
rates in cattle when it moves into new areas. Major CBPP epidemics have been
experienced in eastern, southern and West Africa over the last few years. The
disease is also endemic in some parts of Asia.
Trans-boundary animal diseases exhibit a great deal of dynamism. New diseases
emerge, and old diseases re-emerge. They show a great propensity for sudden
and unexpected spread to new regions, often over great distances. These trends
are likely to continue and even accelerate in the future.
The last 30 years or so have been remarkable for the emergence of apparently
new infectious diseases. This has been spectacular in the medical field, with
the appearance of diseases such as AIDS, Lassa fever, and Ebola. The same has
occurred with animal diseases, with the appearance of bovine spongiform encephalopathy
("mMad cCow" disease), porcine reproductive and respiratory syndrome
(PRRS), post-weaning mortality and wasting syndrome (PMWS) of pigs, Nipah virus
infecting pigs and humans, and equine morbillivirus affecting horses and humans
but now known as Hendra virus. Not only do new infections emerge, but also new
biotypes or antigenic types of existing infectious diseases. A notable example
has been the hypervirulent form of infectious bursal disease that has swept
across much of Europe and Asia in recent years, causing devastating losses to
poultry industries there.
There are a number of factors contributing to the dynamic nature of trans-boundary animal diseases. These include:
An effective national animal quarantine system should always be the first line
of defence against the entry and establishment of trans-boundary animal diseases.
However, even the most sophisticated quarantine service cannot provide an absolute
barrier. Countries, therefore, need a second line of defence, which is the development
of contingency plans and capabilities to respond quickly to high-threat diseases,
should they enter.
If an introduced trans-boundary animal disease can be recognised early whilst it is localised, and a disease control programme can be quickly implemented, the prospect for eradication of the disease with minimal production losses and other costs is markedly enhanced. Conversely, if the disease is allowed to become well established in the country, eradication may be very costly and difficult, or even impractical (particularly if the disease becomes established in wildlife). Thus, the two key principles in combating trans-boundary animal diseases are:
1. Early warning. This is to rapidly detect the introduction of, or sudden increase in the incidence of any disease of livestock that has the potential of developing to epidemic proportions and/or causing serious socio-economic consequences or public health concerns. It embraces all initiatives, mainly based on disease surveillance, reporting and epidemiological analysis, that would lead to improved awareness and knowledge of the distribution and behaviour of disease outbreaks (and of infection) and which allow forecasting of the source and evolution of the disease outbreaks and the monitoring of the effectiveness of disease control campaigns.
2. Early reaction. This is to carry out without delay the disease control activities needed to contain the outbreak and then to eliminate the disease and infection in the shortest possible time frame and in the most cost-effective way or, at least, to return to the status-quo which existed previously and to provide objective, scientific evidence that one of these objectives has been achieved.
The last 20twenty years or so have seen exceedingly rapid advances in scientific knowledge. This has been due, in no small part, to the revolution that has occurred in the fields of genetic engineering and computer science. Much new technology can now be applied to combat trans-boundary animal diseases. The areas in which technical advances to combat these diseases have been most pronounced are:
All of the technology that is available will not be appropriate for all countries
or all circumstances. Indeed, many of the more sophisticated techniques may
only be suitable for specialist institutions such as International Reference
Laboratories. It is important that an appropriate level of technology be selected
for each situation, but that there should be a conscious effort on the part
of national veterinary services to progressively improve their technical capabilities.
It is difficult to ascertain exactly what cause leads directly to what result. However, there are some general trends in livestock industries that are at least partly due to the diseases and issues described above. Some of these are:
Box 3 summarises the similarities and differences between livestock production systems and aquaculture systems.
| Box 3. Similarities and differences between livestock production and aquaculture. | |
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Similarities
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Differences
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Based on what is happening in the livestock sector, some areas where new initiatives are warranted are:
There is no doubt that there will be more, rather than less, disease in small-scale
aquaculture systems as they expand. Increases will be in the level of underlying
endemic disease that must be managed at the farm level, as well as the emergence
of new, sometimes rapidly spreading, epidemic diseases. The impacts from these
will be severe and will threaten industries if planning and actions are not
initiated now. In doing this, there are valuable lessons to be learned from
the livestock sector that has been engaged in this battle for many years.
Solutions are likely to lie in improved management at all levels of the production, marketing and policy chains. Chemical treatment of diseases (including use of antibiotics) as they occur is often not sustainable in the long term. The fight to control disease as aquaculture expands and intensifies will eventually depend on finding management solutions based on good hygiene, sound biosecurity and early detection of disease with appropriate responses. This will require that all levels of the sector, from small-scale farmers through to government policy makers, have a good understanding of the critical points in the system which need to be controlled, as well as the means to control them. If this issue is addressed in a systematic manner, then the impacts of endemic disease and the risk of impacts from devastating epidemic diseases will be reduced.
Baldock, F.C., T. Forman, W. Geering and W. Taylor. 1999. New technologies
in the fight against transboundary animal diseases. FAO-Japan Cooperative Project:
Collection of Information on Animal Production and Health Phase One: Transboundary
Animal Diseases. FAO Animal Production and Health Paper No. 144, 118 p.
Delgado, C., M. Rosegrant, H. Steinfeld, S. Ehui and C. Courbois. 1999. Livestock
to 2020 - the next food revolution. Food, Agriculture and Environment Discussion
Paper No 28. International Food Policy Research Institute (IFPRI), Food and
Agriculture Organization of the United Nations (FAO), and International Livestock
Research Institute (ILRI), 72 p.
FAO. 1999. Production Yearbook 1998, Vol. 52, FAO Statistical Series No. 148.
OIE. 2000. The International Animal Health Code, 9th Edn, Office International
des Épizooties, Paris.
