Early warning enables rapid detection of the introduction of, or sudden increase in the incidence of, a serious disease such as CBPP before it develops to epidemic proportions and causes serious socio-economic consequences. 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). This should allow forecasting of the source and evolution of the disease outbreaks, and monitoring of the effectiveness of disease control campaigns.
The success of a country's capability for rapid detection of introduction or increased incidence of CBPP depends on the following:
- good farmer and public awareness programmes for CBPP and other high-threat epidemic livestock diseases, which implies improving the veterinary-farmer interface;
- training of field veterinary officers, veterinary auxiliary staff, agricultural extension officers, local authorities and cattle owners in the clinical and gross pathological recognition of CBPP and other serious epidemic livestock diseases; training all involved in collection and transportation of diagnostic specimens; and stressing the need for prompt action;
- sustained active disease surveillance, to supplement passive monitoring, based on close coordination between cattle owners, field, laboratory and epidemiology veterinary services, and use of techniques such as participatory questionnaires, serological surveys and abattoir monitoring to supplement field searching for clinical disease;
- dependable emergency disease reporting mechanisms to regional, national and federal veterinary headquarters as appropriate;
- implementation of an emergency disease information system (e.g. TADinfo);
- enhancement of laboratory diagnostic capabilities for CBPP within provincial and national veterinary laboratories;
- development of strong linkages between national laboratories and regional and world reference laboratories;
- strengthening of national epidemiological capabilities to support emergency preparedness and disease management strategies; and
- prompt and comprehensive international disease reporting to the OIE by all countries, and particularly neighbouring countries.
It is beyond the scope of this Manual to discuss these issues in any detail. For more information, reference should be made to the FAO Manual on the Preparation of National Animal Disease Emergency Preparedness Plans (FAO Animal Health Manual, No. 6); the FAO Manual on Livestock Disease Surveillance and Information Systems (FAO Animal Health Manual, No. 8); and the FAO Manual on Participatory Epidemiology (FAO Animal Health Manual, No. 10).
However, a few of the important issues for CBPP early warning preparedness are considered below.
In many countries, it is likely that very few veterinarians or other animal health workers in either the public or private sector will have had any direct, first-hand experience with CBPP or other TADs, as these diseases may never have occurred in the country or may have been exotic for a considerable period. If CBPP is rated as a high-threat disease, this deficiency needs to be rectified by a systematic training programme for all those persons who, in their professional capacity, might possibly be the first to come into contact with an incursion or outbreak of this disease. Because a disease may strike in any part of the country and because of staff turnover, training programmes should be both comprehensive and regular. This training must extend to staff in the remotest parts of the country, as well as to selected officials (agricultural extension officers, local authorities) and cattle owners.
Obviously, it will neither be practicable nor necessary to train personnel to a high level of expertise in these diseases. In most cases it is sufficient that trainees be at least familiar with the basic clinical, pathological and epidemiological features of CBPP, and with what they need to do if they suspect a case of the disease. Perhaps the most important thing to inculcate in people is the mind set that if they are confronted by an unusual disease outbreak in cattle, either in the field or in the diagnostic laboratory, they should include CBPP in the range of their differential diagnostic possibilities and act accordingly. They should be trained in the steps that 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 those personnel who are nominated as members of specialist diagnostic teams (see below).
There are a number of training possibilities that might may be selected as appropriate. These include:
- sending key field or laboratory staff to another country to gain first-hand experience when there is a CBPP outbreak there, or making use of any other opportunities offered for field and laboratory staff to profit from the experience of countries that are in the process of controlling an outbreak (e.g. attending workshops);
- other international training opportunities that may occur from time to time. Several countries that have access to microbiologically high-security laboratory and animal facilities run training courses in which exotic diseases can be demonstrated by experimental infection of susceptible livestock species. Such courses are run in Australia, Republic of South Africa, United Kingdom and USA, and there are opportunities for external students to attend. There is also the possibility for laboratory staff to be trained at World or Regional Reference Laboratories. Training programmes may also be arranged occasionally by other international organizations;
- national emergency disease training workshops, which should be organized as the mainstay of training and should be targeted at government field and laboratory veterinary officers, public health and quarantine veterinarians (including those stationed at abattoirs, markets, border posts, air and seaports), veterinary practitioners, and industry veterinarians. Ideally, these workshops should include representatives from neighbouring countries, and should filter down to farmer level by means of workshops organized by those who have been trained; and
- field diagnostic manuals, which are most useful if they are prepared in a simple, practical and graphic format suitable for keeping always in the vehicle and therefore available for quick reference at the site of a possible disease outbreak.
This is one of the most critical, but sometimes neglected, aspects of preparedness planning for emergency diseases, and for fostering ownership and support among livestock farmers and other key stakeholders for emergency disease control and eradication campaigns. 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 CBPP and other important livestock diseases, and of the benefits to be derived from their prevention and eradication. Furthermore communication strategies should always have an element of rallying the community to the common cause of preventing and fighting a disease epidemic. Ideally, this should result in farmer sanitary defence groups and farmer organizations.
One of the important messages to get across is that it is essential to notify and seek help from the nearest government animal health official as soon as an unusual disease outbreak is seen in cattle (and how to seek help). Publicity campaigns should be directed not only towards farmers, but also to local authorities and livestock traders.
It is recommended that a specialist CBPP diagnostic team be nominated within the country, that can be mobilized when there is a report or rumour of a suspect outbreak in cattle in the field. 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. The equipment should include all that is 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 might include:
(i) a veterinary pathologist from the Central or Regional Veterinary Diagnostic Laboratory;
(ii) a specialist veterinary microbiologist, preferably with first-hand experience or training in CBPP;
(iii) an epidemiologist with extensive experience of endemic diseases in cattle, and a knowledge of cattle farming in the area in question; and
(iv) any specialist required for special examinations.
The team would travel to a disease outbreak site with local veterinary staff if so directed by the CVO, and would be expected to make clinical examinations; collect histories; make preliminary epidemiological investigations, particularly in respect to trace-backs (have any new animals joined the infected herds in recent months, and, if so, where did they come from?) and trace-forwards (have any animals left the infected herds in recent weeks and, if so, to where did they go?); perform necropsies on animals that were killed in an advanced stage of the disease or on animals recently dead; and collect a range of diagnostic specimens appropriate to the endemic and exotic diseases included in the differential diagnosis, and transport these specimens under suitable conditions back to the laboratory.
A good framework for investigation of field outbreaks is given in Appendix 1.
The team should also be able to take any immediate disease control actions at the outbreak site that are necessary, and should have the necessary authorities to do this.
The team would be expected to report back immediately to the State, Provincial and Regional Veterinary Officers and the CVO on their assessment of the disease outbreak, including steps taken to secure a confirmatory diagnosis, and on their advice on further disease control strategies, including declaration of infected and surveillance zones.
The rapid and certain diagnosis of diseases can only be assured in fully equipped laboratories, having access to a range of standardized diagnostic reagents, and with experienced staff and a sufficient throughput of diagnostic specimens to maintain expertise. Additionally, development of diagnostic expertise for exotic diseases for tests that require handling the live agent should only be attempted in microbiologically secure laboratories.
It would therefore 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, it is to be expected that at least all 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 preliminary identification of aetiological agents for most if not all emergency livestock diseases could be attempted. If CBPP is deemed to be a very high threat disease, consideration should be given to developing capabilities for some primary key diagnostic tests.
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. These should ideally consist of leak-proof primary containers, such as glass universal bottles with a metal screw-cap with rubber washer, or good quality plastic screw-top jars. These are then packed into a leak-proof secondary container (e.g. a steel paint tin or a plastic or styrofoam cool-box) with absorbent material and an ice-pack. This is finally placed into a robust outer container with good labels. Specimen advice notes should also be provided (see Chapter 2).
For CBPP, there is a network of FAO Reference Laboratories and Collaborating Centres and OIE Reference Experts and Laboratories around the world, which are available to provide advice and assistance to countries. Their names, full contact details and geographical areas of responsibility are shown in Appendix 2.
As part of their CBPP contingency planning, countries should establish contact and a dialogue with appropriate Reference Laboratories and Collaborating Centres. They should determine the nature and range of diagnostic specimens or isolated agents that should be sent for confirmatory diagnosis or further characterization; any transport media that should be added; method of packaging and refrigeration; and labelling of package including correct address and any necessary customs or IATA declarations. This information should be documented in the contingency plans.
It is very 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 from different geographical locations and at different phases of the outbreak be forwarded. Submission of samples to any laboratory outside the country of origin should always be subject to prior agreement with the recipient, with transportation in containers meeting IATA regulation standards.
Full use of Reference Laboratories and Collaborating Centres should also be made for the help that they can provide for training opportunities, provision of specialized advice in planning and standardized diagnostic reagents, etc.
Whilst the whole range of surveillance techniques - summarized here in section 5.1 and described in greater detail in FAO Animal Health Manuals No. 8 and No. 10 - should be applied, emphasis is given to two fundamental techniques for CBPP surveillance, namely abattoir monitoring and clinical surveillance.
Abattoir monitoring is a cheap and highly effective method of surveillance for CBPP. The coverage that can be provided depends on the proportion of cattle in the country that are slaughtered in controlled abattoirs with meat inspection facilities. Meat inspection staff should be trained in correct methods for palpating, sectioning and examining pleura and lungs during inspection of cattle carcasses. They should receive special training in the key pathological features of CBPP, and should be provided with forms on which they may record their findings. These should incorporate simple diagrams of lungs for drawing the location of lesions. There is also the need to monitor informal slaughter sites.
Key Indicators of CBPP in Meat Inspection
Diagnostic samples should always be collected from suspect lungs, and meat inspectors should be trained in how to do this, and should also be provided with collection kits. Finally, there should be simple, direct methods for them to report their findings, together with key epidemiological information on the owners and source of the cattle.
Both active and passive clinical surveillance are also valuable for the early detection of CBPP. Passive clinical surveillance should be encouraged through a comprehensive national programme to the extent that everyone who comes into contact with cattle from field veterinarians, to animal health assistants, farmers, traders and down to animal attendants should be stimulated to look out for the key clinical signs of CBPP and to report any suspect cases
Simple pictorial booklets on CBPP, in appropriate languages, should be widely distributed.
Key signs to look out for in clinical surveillance for CBPP
OIE has developed comprehensive surveillance standards for CBPP, particularly in the context of defining CBPP-free zones and countries. These are to be found in Appendix 3.