Early warning is the rapid detection of the introduction of, or sudden increase in, any disease of livestock which has the potential of developing to epidemic proportions and/or causing serious socio-economic consequences or public health concerns. It embraces all initiatives and is mainly based on disease surveillance, reporting and epidemiological analysis. These lead to improved awareness and knowledge of the distribution and behaviour of disease outbreaks and infection, allow forecasting of the source and evolution of the disease outbreaks and the monitoring of the effectiveness of disease control campaigns.
Disease surveillance should be an integral and key component of all government veterinary services. This is important for early warning of diseases, planning and monitoring of disease control programmes, provision of sound animal health advice to farmers, certification of export livestock and livestock products and international reporting and proof of freedom from diseases. It is particularly important for animal disease emergency preparedness.
It is beyond the scope of this manual to deal comprehensively with the requirements of disease surveillance. Reference should be made to the FAO animal disease surveillance handbook, which is in preparation. However, the approaches to be adopted for a comprehensive system of disease surveillance are summarized below.
Passive disease surveillance
Passive disease surveillance is the routine gathering of information on disease incidents from sources such as requests for assistance from farmers, reports from field veterinary officers and livestock officers, submission of diagnostic specimens to laboratories and the results of laboratory investigations. Routine disease reports may also come from other sources such as abattoirs and livestock markets.
It is important that passive surveillance systems be strengthened and that the disease information they yield be effectively captured and analysed. However, it should be recognized that complete reliance on passive surveillance usually leads to significant underreporting of diseases. It is essential that passive surveillance be supplemented by a strong system of active disease surveillance, particularly for emergency animal diseases.
Active disease surveillance
Active disease surveillance requires purposeful and comprehensive searching for evidence of disease in animal populations or for verification that such populations are free of specific diseases. Active disease surveillance programmes may be of a catch-all nature to detect any significant disease occurrences, targeted against specific high-threat diseases or designed to monitor the progress of individual disease control or eradication campaigns.
The components of successful active disease surveillance programmes are:
Epidemic livestock diseases are frequently spread by the movement of infected animals. In active disease surveillance of such diseases, emphasis must be given to situations where animals and people are on the move. This includes livestock markets, livestock trading routes, border areas and situations such as nomadism, transhumance and refugee movements from wars and civil strife.
Livestock markets and other congregations of animals are a very important potential source for the rapid spread of epidemic diseases. They should be a major focus for disease surveillance and should be carefully controlled during disease outbreaks
Wildlife disease surveillance must not be overlooked. Wildlife may provide a reservoir of infection for some diseases, but may also act as a sensitive indicator of diseases that are not clinically apparent in adjacent livestock populations. The latter has occurred recently with African Lineage 2 rinderpest virus in East Africa. Close cooperation is required between veterinary and wildlife authorities. As direct examination of wildlife by capture techniques or slaughter is expensive and often difficult to organize, where possible sera and other diagnostic specimens should be collected when such wildlife surveys are carried out.
Emergency disease reporting
Most if not all countries have evolved disease reporting mechanisms that are primarily designed for routine endemic disease occurrences. These mechanisms often suffer from one or more serious deficiencies, including overlong reporting chains from local to district to provincial and finally to national offices, with the consequent risk of inordinate delays and distortion of information at each level; and collection and transmission of information that is based on poor epidemiological surveillance or diagnostic methods or is inadequate for good disease control decision-making.
For these reasons, special emergency disease reporting mechanisms for potentially serious disease outbreaks or incidents must be put in place as an essential component of preparedness plans. These should allow critical epidemiological information to be transmitted to national veterinary headquarters rapidly and efficiently, preferably on the same day. This may be done by telephone, facsimile, e-mail, radio, or courier-whichever is the most appropriate for the circumstances and the location. Local and regional veterinary offices should in any case be provided with the necessary communications equipment and field and laboratory staff should have a list of contacts and alternatives so that emergency disease reports may be received and acted upon quickly at their destinations.
In the case of an emergency report on a disease outbreak or incident, the basic information that needs to be conveyed is:
All transboundary and other emergency animal diseases should be made compulsorily notifiable within the country.
Emergency disease information system
All countries should have a fully operational disease information system so that there can be a two-way flow of information between national veterinary headquarters, government veterinary diagnostic laboratories and regional veterinary offices (or local disease control headquarters) that will allow the efficient monitoring of the progress of disease eradication or control programmes. This is even more important for responses to emergency diseases. The development of a disease information system is an essential part of national animal disease emergency preparedness planning. It is desirable but by no means essential that this be computerized.
The information that is captured in this system should be limited to the essentials for the planning, implementation and monitoring of disease control campaigns and for international reporting. The information system should not be cluttered with data that are not required for decision-making. It should be emphasized that the emergency disease information system needs to be a two-way process, with adequate feedback from national veterinary headquarters to the field and laboratory veterinary staff who originally collected and processed the information.
The following provides an indication of the type of information that may be included in the emergency disease information system:
Geographic locations feature prominently in the above disease information requirements. The emergency disease information system should therefore incorporate a facility for mapping. At a later stage in its development, consideration could be given to the incorporation of a geographic information system (GIS).
Assistance can be provided to countries in their development of emergency diseases information systems by the FAO/EMPRES programme. A transboundary animal diseases information system (TADINFO) is being developed by EMPRES which can be made available to countries that do not already have a suitable system in place.
In many countries, particularly the developing ones, it is unlikely that many veterinarians or other animal health workers in either the public or private sector will have had first-hand experience with transboundary or other emergency animal diseases, as these diseases may never have occurred in the country or may have been exotic for a considerable period. This deficiency needs to be rectified by a systematic training programme for all those who, in their professional capacity, may be the first to come into contact with an incursion or outbreak of such a disease. Because a disease may strike in any part of the country and because of staff turnovers, training programmes should be both comprehensive and regular. This training must extend to staff in the remotest parts of the country.
Obviously, it will be neither practicable nor necessary to train personnel to a high level of expertise in these diseases. In most cases it is sufficient for trainees to be familiar with the basic clinical, pathological and epidemiological features of risk diseases and to know what to do if they suspect one of these diseases. Perhaps most important is to inculcate in people an awareness that if they are confronted by an unusual disease outbreak, either in the field or in the diagnostic laboratory, they should include exotic diseases in the range of their differential diagnostic possibilities and act accordingly. They should be trained in the steps they need to take to secure a confirmatory diagnosis, including collection and transport of diagnostic specimens, and in the immediate disease control actions that need to be instituted at a disease outbreak site. More specialized training will be needed for personnel who are nominated as members of specialist diagnostic teams (see p.28). Training should also be intensified for diseases judged to be of very high and immediate threat.
A number of training possibilities may be selected as appropriate, including sending key field or laboratory staff to another country to gain first-hand experience when there is a major disease outbreak. While this is the best type of training, it is unpredictable and expensive. Nevertheless, this possibility should be explored when there is a disease emergency in a neighbouring country. Staff would be able to observe the disease and disease control procedures in a similar environment and they would also provide additional human resources for the recipient country responding to the emergency.
Other international training opportunities may occur from time to time. Several countries with access to microbiologically high-security laboratory and animal facilities, such as Australia, the United States, the United Kingdom and South Africa, run training courses in which exotic diseases can be demonstrated by experimental infection of susceptible livestock species. There may be the opportunity for external students to attend. There is also the possibility of training for laboratory staff at world or regional reference laboratories or through programmes organized by the Joint FAO/IAEA Division. Training programmes may also be arranged occasionally by other international organizations.
To ensure early recognition of emergency diseases, all veterinarians and animal health workers should be trained to recognize basic clinical features, and to report immediately on any suspicions that arise during their everyday work
National emergency disease training workshops should be organized as the mainstay of training and should be targeted at government field and laboratory veterinary officers, veterinary practitioners, industry veterinarians and public health and quarantine veterinarians including those stationed at abattoirs, markets, border posts and air-and seaports. Formal presentations and discussion sessions on the major emergency diseases should be supplemented as much as possible by audio-visual teaching aids, including colour slides and videos on the diseases. A list of available training aids is shown in Appendix 2. The presentations should also include discussion of the basic principles and strategies for preventing and eradicating the diseases. Practical demonstrations may also be carried out on the correct methods for collection and dispatch of diagnostic specimens.
At the same time, instruction should be provided on disease reporting responsibilities and procedures, disease surveillance and other field epidemiology methods and immediate disease control actions at the outbreak site(s).
Similar but simpler training workshops should be organized for auxiliary veterinary staff.
Field diagnostic manuals are most useful if they are prepared in a simple, practical and graphic format whereby they can always be carried in a vehicle and can be available for quick reference at the site of a disease outbreak. The manual should cover essential information on the aetiological agent, host species, epidemiology, clinical signs, gross pathology, differential diagnosis and collection of diagnostic specimens for each of the emergency diseases.
Training in emergency disease recognition and management should also be an integral part of the curriculum of undergraduate veterinary students in universities.
This is one of the most critical, but sometimes neglected, aspects of preparedness planning for emergency diseases. It is also important for fostering a sense of participation in and support for emergency disease control/eradication campaigns among livestock farmers and other key stakeholders. It also engenders a “bottom-up” approach to planning and implementation of disease control programmes to complement the more traditional “top-down” approach adopted by governments.
The communication strategies should aim to make stakeholders aware of the nature and potential consequences of important livestock diseases and of the benefits to be derived from their prevention and eradication. Furthermore, they should always have an element of rallying the community to the common cause of fighting a disease epidemic.
When possible, professional communicators and extension experts should be enlisted to help design and carry out awareness and publicity campaigns. Ideally, personal visits and discussions with farming communities and livestock traders, etc. are preferable, but newspapers, radio and television can reach a large target audience quickly. Radio programmes have proved to be a very effective method for spreading the message. These should be broadcast at times of the day when most farmers could be expected to be listening to the radio, which may be early in the morning or at night.
Early warning of outbreaks of potentially serious livestock diseases is only likely to occur if farmers are prompt to seek help from their local government veterinary officer, private veterinary practitioner, livestock officer or animal health assistant when they experience an unusual disease in their animals. This is the vital first link in bringing an occurrence of such a disease to official attention. It is therefore worth while devoting considerable attention to farmer and other public awareness programmes in emergency disease preparedness planning.
An essential prerequisite for encouraging farmers to make rapid contact with their district veterinary office or equivalent for help when faced with a disease outbreak is that a high level of trust and confidence has been established between the farming community and local animal health officials. This is not something that happens overnight. Farmers are more likely to report unusual disease occurrences at an early stage if they perceive that there will be tangible benefits in doing so. The required level of trust and confidence needs to be built up over time by regular visits to farming communities, well-planned extension programmes and an established pattern of assistance and advice on more routine animal health matters. Local animal officials should be both accessible and easy to contact. Reports of unusual disease incidents should always be taken seriously and investigated promptly and thoroughly, even if on the surface they may appear to be false alarms.
Awareness campaigns on the more important emergency livestock diseases should become a routine element of extension programmes for farmers. They may be targeted particularly at diseases that have been identified as being of highest threat in risk analyses (see Chapter 3) and at high-risk areas for entry and/or occurrence of these disease. Farmer awareness campaigns should encompass:
A series of audio-visual aids may be prepared or obtained from external sources to support extension programmes. These should be designed for specific audiences bearing in mind the level of sophistication appropriate for each group. They may include posters, leaflets and videos. A selection of training aids which may be suitable for this purpose are listed in Appendix 2.
Livestock traders are another important target group for public awareness campaigns, but they are often overlooked. The movement of animals through livestock traders is often the key epidemiological factor in the spread of epidemic livestock diseases. The need to build up a climate of trust and confidence between animal health officials and livestock traders is just as important as that discussed for farmers. The general themes for emergency disease awareness should also be similar, although emphasis should be placed on the importance of sourcing animals from disease-free areas where possible, not buying any sick stock and following any rules about quarantine and vaccination, testing or identification of animals. The potential consequences of the occurrence of a disease for internal and international trade should be emphasized.
Public awareness campaigns
Campaigns targeted at specific groups should be supplemented by more general public awareness programmes. These can be channelled through media outlets including newspapers, radio and television. Radio broadcasts can be an extremely powerful (and perhaps the only) means of reaching farming communities and nomadic groups in remote areas or areas that have been rendered relatively inaccessible for reasons such as civil strife.
It is recommended that specialist diagnostic teams be ready to be mobilized when there is a report from the field of a suspected emergency animal disease. These arrangements should be made well in advance of any emergency and the members should be available and equipped to travel to a disease outbreak site at short notice. In this case they must have at their disposal all the equipment needed for the preliminary investigation of a disease and for collection and transport of diagnostic specimens.
The composition of the diagnostic team will vary according to circumstances but may include:
Radio broadcasts can be an extremely powerful tool in public awareness campaigns
The specialist diagnostic team should be given a high level of training in at least the identified high-priority emergency diseases and in participatory techniques.
The team would travel to a disease outbreak site with local veterinary staff, as directed by the CVO. They would be expected to make clinical examinations, collect histories and make preliminary epidemiological investigations, particularly in respect to tracebacks (have any new animals joined the infected herds or flocks in recent weeks and where did they come from?) and traceforwards (have any animals left the infected herds or flocks in recent weeks and where did they go to?). They would also autopsy sick or very recently dead animals and collect a range of diagnostic specimens appropriate to the endemic and exotic diseases included in the differential diagnosis and transport these back to the laboratory.
The team should also be able to take any immediate disease control actions at the outbreak site and should have the necessary authority to do this.
The specialist diagnostic team would be expected to report their assessment of the disease outbreak immediately to the state/provincial/ regional veterinary officer and the CVO, specifying steps taken to secure a confirmatory diagnosis and advice given on further disease control strategies, including declaration of infected and surveillance zones.
The rapid and accurate diagnosis of diseases can only be assured in fully equipped laboratories that have a range of standardized diagnostic reagents, experienced staff and a sufficient throughput of diagnostic specimens to maintain expertise. It should be noted that development of diagnostic expertise for exotic disease using tests that require handling the live agent should only be attempted in microbiologically high-security laboratories.
It would be impractical and excessively costly for most countries to maintain a national veterinary diagnostic laboratory that has full capabilities for confirmatory diagnosis of all transboundary and other emergency diseases, many of which will be exotic. However, countries that have significant livestock populations should have a veterinary diagnostic laboratory that is equipped and competent to undertake a broad range of standard techniques in pathology, virology, bacteriology and serology to the standard where the isolation and preliminary characterization of aetiological agents for emergency livestock diseases could be attempted. For very high-threat transboundary animal diseases, consideration should be given to developing capabilities for some key diagnostic tests, such as ELISA antigen and antibody detection tests and fluorescent antibody tests.
The OIE Manual of standards for diagnostic tests and vaccines provides authoritative information on diagnostic procedures for OIE List A and List B diseases.
Specimen transport containers should be kept at both central and state or provincial veterinary laboratories and should be made readily available for field veterinary officers and specialist diagnostic teams. They should ideally consist of leakproof primary containers such as glass universal bottles with a metal screw-cap and rubber washer. These should then be packed into a leakproof secondary container, such as a steel paint tin, with absorbent material and an icepack if chilling is required. This container should be placed in a robust outer container which must be clearly labelled. Specimen advice notes should also be provided.
There is a network of FAO and OIE reference laboratories and collaborating centres around the world which are available to provide advice and assistance to countries. They are designated for specific diseases or for broader subjects such as emergency preparedness for transboundary animal diseases, vaccine quality assurance and biological standardization and veterinary epidemiology and economics. Full use should be made of these reference laboratories and collaborating centres; their names, full contact details, subjects and geographical areas of responsibility are shown in Appendix 1.
FAO reference laboratories provide consultations, assist in making diagnoses, develop diagnostic capability, maintain a reference collection of disease agents and produce and standardize reagents. They also assist in characterization of causative agents and in training activities.
FAO collaborating centres provide technical advice, expertise and consultations on designated subjects pertinent to FAO headquarters, field projects and member countries. FAO also assists in the organization and implementation of training activities.
As part of their emergency disease preparedness planning, countries should establish and maintain contact with appropriate reference laboratories and collaborating centres. In the case of reference laboratories, they should determine the nature and range of diagnostic specimens or isolated agents that should be sent for confirmatory diagnosis or further characterization, specify any means of transport to be added, the method of packaging and refrigeration and the labelling of packages, including correct address and any necessary customs or IATA declarations. This information should be carefully documented.
It is important that potential or confirmed aetiological agents from emergency disease outbreaks be sent to the appropriate international reference laboratory for further characterization. It is recommended that several isolates taken from different geographical locations and at different phases of the outbreak be forwarded to the laboratory.
preparation of the ELISA test
Characterization studies at the reference laboratory will help to select the most appropriate disease control and eradication programmes, including the right vaccine for the situation. Furthermore, molecular epidemiology studies (based on nucleotide sequencing and preparation of phylogenetic maps or dendrograms) will allow detailed comparisons to be made with viruses or other agents from other geographical areas, thus throwing light on their origins and spread on a regional or global scale.
Full use should also be made of reference laboratories and collaborating centres for the help that they can provide for training opportunities, provision of specialized advice in planning and standardized diagnostic reagents.
International Office of Epizootics (OIE)
OIE has obligatory disease reporting requirements for member countries which should be factored into emergency disease preparedness plans. A staff member in the national veterinary headquarters should be responsible for preparing draft international disease reports, for OIE and elsewhere, to be approved by the CVO. The head of the epidemiological unit would generally be the most appropriate person to carry out this function.
In brief, countries should notify OIE within 24 hours of any of the following events:
Thereafter, weekly reports should be sent to OIE to provide further information on the evolution of the disease incidence until it has been eradicated or the situation stabilized.
Monthly reports should be sent regarding the absence or presence and evolution of diseases in List A, and findings of epidemiological importance for other countries with respect to those diseases not on List A. Annual reports should be sent on all diseases in Lists A and B and on any other diseases considered to be of socio-economic importance or of major veterinary interest.
There are several regional organizations that have been established, inter alia, to coordinate livestock disease control programmes at a regional level, foster international cooperation on animal health issues and facilitate safe international trade in livestock and livestock products.
These organizations may require their member countries to report and share information on diseases. Examples of such organizations are:
FAO EMPRES livestock programme
A global early warning system is being established for transboundary animal diseases within FAO's EMPRES programme. This will be part of TADINFO and is designed to complement the OIE system. Its purpose is to support national and international animal disease control efforts rather than trade (as in the OIE system).
Epidemiological data for global TADINFO will be sourced from regional reporting systems, OIE, reference laboratories, SID (the IAEA serosurveillance database) and from various unstructured sources such as consultant reports and PROMED postings. This is planned for use not only as a historical disease database but also as a disease mapping and geographic information system (GIS) that will allow epidemiological analyses to be carried out on the mechanisms of the international spread of TADs.
National animal disease emergency planning committees should establish a regular working relationship with the EMPRES group at FAO headquarters in order to obtain the full benefits of the TADINFO system in obtaining early warning of disease threats and for assistance in developing prevention and contingency plans against these diseases.
TADINFO (Transboundary Animal Disease Information system), a specialized software package for the systematic recording and analysis of livestock disease information, developed by the EMPRES-Livestock group of FAO
Special arrangements with neighbouring countries and trading partners
Transboundary animal diseases by definition do not respect borders and can spread rapidly from country to country. Neighbouring countries should therefore cooperate closely in the control of these diseases. Unless this is done, the disease control efforts of individual countries will be continually frustrated. Part of this cooperation should be the rapid sharing of information on the occurrence of new diseases and on the spread of existing epidemic diseases to new areas, particularly near shared borders. Arrangements should be made for this information to flow not only between the respective CVOs, but also at a local level between contiguous district or regional veterinary offices along the borders.
Similarly, arrangements should be made for the rapid flow of disease information between the CVOs of major trading partner countries for livestock and livestock products.