Epidemic livestock diseases have been showing an alarming tendency to spread, inter alia, through increased mobility of people, goods and livestock, changes in farming systems, climatic changes and weakened livestock health services
At the end of the nineteenth century, a pandemic of rinderpest decimated the livestock and wildlife animal populations of Africa. It is estimated that some 90 percent of the cattle population were eliminated by the plague. Incursions of the disease into Europe, and most notably the epizootic that occurred in Belgium in 1920, led to the creation of the Office international des épizooties (OIE) in 1924.
The twentieth century witnessed a steady decline in the incidence and extent of epizootic diseases in industrialized countries of Europe, thanks to developments in technology, the farming industry, animal health services and the dedicated investment of adequate resources. However, towards the end of the twentieth century and now at the beginning of the twenty-first, epidemic livestock diseases have been showing an alarming tendency to spread, inter alia, through increased mobility of people, goods and livestock, changes in farming systems, climatic changes and weakened livestock health services.
It is in this context that the concept of a global early warning system for priority transboundary animal diseases of livestock was initially raised during the review of the EMPRES programme in 1996 (expert consultation, 24-26 July 1996). This became necessary in order to help member countries to be better prepared to fight animal diseases of an epizootic nature.
In 1998, the International Committee of the OIE further endorsed the concept of early warning for animal diseases through its Resolution No. XIII (Forecasting systems using the laboratory and epidemiology to prevent outbreaks of existing and emerging diseases). Chapter Six of this Resolution states:
"Member countries, the OIE and the World Health Organization (WHO) collaborate with the Food and Agriculture Organization of the United Nations (FAO) to progressively develop a hierarchical global early warning system, including pilot projects to be carried out on a regional basis, which complements, but does not duplicate or replace, the existing reporting obligations of the OIE."
Finally, at the Ministerial Meeting on FMD held at FAO headquarters, Rome, on 6 November 2001, during the thirty-first session of the biannual FAO Conference, the FAO Director-General, Dr Jacques Diouf, reaffirmed the need to establish a system similar to that already developed in FAO for food crops under the name "Global Information and Early Warning System on Food and Agriculture" (GIEWS, see box). The envisaged early warning system for transboundary animal diseases would take account of the official reporting system of the OIE along with ground truth disease investigations, and epidemiological and laboratory studies to aid prediction modelling and international early warning.
GLOBAL INFORMATION AND EARLY WARNING SYSTEM ON FOOD AND AGRICULTURE GIEWS was established in 1975 in the wake of the world food crisis of the early 1970s on the recommendation of the World Food Conference (1974). The Conference recommendations were endorsed at the twenty-ninth session of the UN General Assembly. The ultimate aim of GIEWS is to avert hunger and suffering by providing policy-makers and policy analysts with accurate, timely and appropriate information on food supply and demand. In the above context, early warning signifies the prediction of a food crisis before it occurs. GIEWS monitors global food supply and demand in order to provide timely warnings of impending food supply problems facing individual countries.
The system continually receives economic, political and agricultural information from a wide variety of official and unofficial sources. Institutional links and information-sharing agreements have been established with several UN organizations, 116 governments, 4 regional organizations and over 60 non-governmental organizations (NGOs). The system maintains regular contact with FAO's regional, subregional and country offices and most of FAO's technical units for information sharing and for the development of methodologies. In Africa, GIEWS is currently using the Advanced Real-Time Environmental Monitoring Information System (ARTEMIS) to assess crop production in Africa and underline areas at risk of facing food security problems. ARTEMIS and the Agrometeorological Group in support of GIEWS ARTEMIS has been in operation since August 1988, receiving, processing, archiving and disseminating low-resolution remote sensing imagery in support of FAO's programmes on early warning for food security, and migrant pest and disease control. ARTEMIS supports the operational monitoring of seasonal growing conditions and vegetation development over Africa. The monitoring is based on hourly Meteosat and daily NOAA-AVHRR data, for use in early warning for food security and desert locust control. This includes routine distribution of ARTEMIS images, containing information about rainfall and vegetation activity, by electronic means to users at FAO headquarters and at regional and national levels. FAO continues to support the establishment and/or improvement of local reception and/or processing systems using low-resolution environmental satellites, including the development of improved interpretation techniques and user-friendly analysis software.
ARTEMIS uses Meteosat-based products, such as Cold Cloud Duration (CCD), to generate estimated ground rainfall digital images. ARTEMIS also uses the NOAA/AVHRR and SPOT-Vegetation based assessments of vegetation cover, such as the Normalized Difference Vegetation Index (NDVI), for operational monitoring of crop conditions in the Horn of Africa. Assessments of crop growing conditions and related food production outlook are based on agrometeorological observations combined with remote sensing and other relevant socio-economic information. |
The envisaged GEWS for TADs must be linked to early reaction which would quickly initiate visits of experts, technical cooperation programmes, quarantine advice, contingency plans, disease recognition and diagnostic assistance, and vaccine sourcing
In order to be effective, a global early warning system for TADs should be:
Tightly focused. It should be tightly focused on major epizootics, such as the OIE list A diseases (see box), and utilize and build on existing national and international disease reporting structures and disease intelligence mechanisms.
OIE LIST A DISEASES
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Accurate and timely. Emphasis must be given to helping member countries to access accurate and timely information, which is necessary to understand the epidemiology of a disease at international and regional levels and the subsequent threat on national boundaries. This encompasses fully utilizing all potential sources of information on disease incidents, well-coordinated field and laboratory services, and passive and active disease searching in the field.
However, formal mechanisms of disease reporting have often failed to bring to the fore an emergency situation and the early signs of a disease. While these systems must be strengthened, it is critical to use innovative methods to overcome this problem (see previous section on disease intelligence). This will become even more important during the advanced stages of a disease eradication campaign, e.g. the Global Rinderpest Eradication Programme, when it will become critical to detect remaining pockets of infection in an otherwise susceptible livestock population. In such circumstances, it will be necessary to utilize a mix of techniques that includes comprehensive seromonitoring, abattoir monitoring, incentive-aided disease searching, etc.
Value-added. The system should develop capabilities that will enable it to undertake comprehensive epidemiological analysis and risk assessments of disease outbreaks that will form a solid platform for advising the outbreak country, neighbouring countries and trading partners on the most appropriate prevention control actions. The epidemiological analysis may include antigenic and molecular analysis (nucleotide sequencing) of virus strains at reference laboratories, disease mapping, disease tracing, risk assessment, immune status of livestock populations, insect vector identification and population dynamics.
Action-oriented. It is important to stress that the ultimate goal of the system should be to provide advice and assistance to countries on request following early warning of an imminent disease threat. The envisaged Global Early Warning System (GEWS) for TADs must therefore be linked to early reaction which would quickly initiate visits of experts, technical cooperation programmes, quarantine advice, contingency plans, disease recognition and diagnostic assistance, and vaccine sourcing. It is essential to understand that an early warning system without the follow-up response would be a purely academic exercise with little practical value. Therefore, it is vital that the early assessment and warning are linked to the response mechanism so that the end goal of helping the people affected by the crisis is achieved.
Accessible. To improve international preparedness for epidemic response, it is essential to collect information worldwide on ongoing outbreaks, or rumours of outbreaks, and then disseminate this information (verified information only) at regional and national levels to allow timely action and prevent the disease from spreading. The critical point is that the information must get to the key people who will use the information by the most direct and fastest route. Disease distribution maps, epidemiological analysis reports and emergency disease advice notices should be made available rapidly through newsletters, emergency bulletins, Web sites and mailing lists. In particular situations, more direct communication with affected and threatened countries is necessary.
The eighth joint OIE/WHO/FAO coordinating meeting was held at FAO headquarters in Rome on 5 and 6 February 2002 and deliberated extensively on the feasibility of an international consortium on "Global Early Warning Systems for Animal Diseases". The tripartite meeting was attended by representatives of the three international organizations, and was chaired by the OIE Director-General, Dr Bernard Vallat.
Decision-making tools for early warning developed by FAO were presented during the meeting, including the livestock geography expert system, the Global Livestock Production and Health Atlas (GliPHA), TADinfo software and the RVF regional surveillance network in West Africa. The new OIE policy for animal health information focusing on early warning and the WHO Global Outbreak Verification System were also presented during this session.
At the end of the meeting, it was agreed that a joint OIE/WHO/FAO global early warning system would be an extremely valuable tool for the international community. It was also decided that a series of meetings involving a focal point nominated by each organization will be organized to draft a project document outlining the features of this global system.
