FAO-OIE-AU/IBAR-IAEA
Consultative Group Meeting on CBPP in
Africa
Towards sustainable CBPP control programmes for
Africa
(Rome, 12 - 14 November 2003)
Preamble
The continuing spread of CBPP disease, has confirmed the decreased capability of the control of the disease throughout Africa. The reasons for this include gaps in the basic understanding of the disease and the implementation of effective surveillance and control programmes. This prompted FAO together with the OIE, AU/IBAR and IAEA to convene a joint meeting of specialists to review the current situation with CBPP disease and to suggest actions for improvement of this situation. The meeting was held at FAO, Rome from 12 - 14 November 2003. Specialist working groups reflected on the current knowledge brought together here and deliberated on the needs for applied research and policy under the headings:
CBPP control strategies;
Tools for CBPP Control - Vaccines, and;
Tools for CBPP Control - Use of Antibiotics and Diagnostic Tests.
The recommendations emanating from this meeting are as follows:
CBPP Control Strategies
Introduction
Whilst there is no doubt that CBPP is considered an important disease of cattle in Africa, there is scant data to accurately measure its extent and socio-economic impacts. The suppression of incidence of CBPP, especially in endemic zones, and the maintenance of disease free zones against disease incursions from neighbouring areas are the main aims of control efforts. To achieve these, given complex cross-border political and animal production systems, coordination of policy within countries and within the sub-region will be necessary. Concerted control strategies and actions be they vaccination, chemotherapy, or a combination may then be applied to full effects.
Considerations:
1. Cognizant of the fact that CBPP is widely regarded by veterinary policy makers to be a disease of strategic importance there is a need to verify the livelihoods impact of CBPP relative to other animal health issues.
2. Because CBPP is a strategic disease in many sub-regions of sub-Saharan Africa efforts directed toward defining more accurately the location and role of primary endemic areas in the persistence and spread of CBPP is vital.
3. Cost-beneficial application of CBPP vaccine is central to the progressive control of the disease. Targeted vaccine application in contrast to mass vaccination may be appropriate in some situations (as recommended in 2000).
4. Vaccination provides the basis for all feasible control strategies. It is therefore vital that only safe and effective vaccines are supplied to service providers. Furthermore, continued efforts to ensure the timely availability of thermostable vaccine needs to remain a priority.
5. Considering that modelling studies have indicated that strategic use of antibiotics may be beneficial their use needs to be considered.
Specific Recommendations
1. The strategic approach to CBPP should be based on progressive control leading ultimately to area-wide freedom from the infection. A long-term (10 to 15 year) programme encompassing the following should be applied:
Impact assessments of CBPP at regional, national and zonal levels need to be conducted to justify the anticipated expenditure required for progressive control of CBPP. Participatory approaches are among appropriate methods to achieve this end. These studies should be applied in all sub-regions (clusters of countries) of sub-Saharan Africa;
Cost-benefit analyses of the strategies in force in selected countries of the 3 subregions;
Depending on the epidemiological situation strategies need to be applied to free and epizootic regions as defined in the report of the CBPP Consultative Group meeting of 2000. For endemic regions targeted vaccination or other alternative strategies need to be investigated.
2. A mechanism to enable independent accreditation of CBPP vaccine quality for African countries needs to be established. Ideally, this should be based on the revival of PANVAC.
3. Research needs to be continued into:
Antibiotic treatment of clinical cases;
Improved vaccines and diagnostic tools;
Targeted application of vaccine as a strategy to improve progressive control of CBPP.
4. Pilot projects located in the field and directed towards improved integrated control of CBPP (including antibiotic treatment and liberalization of vaccine availability) need to be undertaken in carefully defined areas and the results made available to all interested parties.
5. CBPP control programmes could be used as a model on which to base improvement of veterinary services, especially in respect of surveillance, control and private/public sector collaboration.
6. Disease modelling is an appropriate tool for improved understanding of the epidemiology and impact of CBPP and its use should be encouraged.
7. Financial planning to ensure adequate financing of the progressive control of CBPP in sub-Saharan Africa.
Tools for CBPP Control - Vaccines
Introduction
The task of this working group was to consider progress on recommendations made at the two previous consultative group meetings on research of new and existing vaccines. In particular we looked at improvements in existing vaccines, input of PANVAC and the need for independent quality control; construction of vaccines that allow DIVA type differentiation of infected and vaccinated animals; and the set up of a database of vaccine producers, their capacity and the current need for vaccine doses in Africa.
Considerations and Specific Recommendations
The group recognized that most of the recommendations made at the last two meetings had been achieved. However the use of T1 44 and T1 SR vaccines needed to be reconsidered in the view of adverse reactions seen with the former in certain circumstances. Little progress had yet been made on the development of new vaccines. To date little was known of the molecular mechanisms of pathogenicity although some progress was made on virulence factors.
8. Concerning the improvement of existing vaccines and their use:
PANVAC is advised to investigate improvements in vaccine formulation including the use of diluents in relation to improved titres and thermal stability. This also includes testing of current vaccines for the stability of pH after reconstitution with currently used diluents;
Results of vaccine boosting experiments which are ongoing at KARI should be published within the year;
Results of experiments to investigate the use of trehalose in the freeze-drying medium to improve the thermotolerance of CBPP vaccines should be published.
9. Concerning the input of PANVAC:
Independent external quality control must be re-established in PANVAC;
All vaccines used at national level should be certified by PANVAC;
AU/IBAR should fully support the operational activities of PANVAC;
PANVAC should continue to strictly apply OIE guidelines on CBPP Vaccine manufacture.
10. Concerning the development of new vaccines:
Encourage basic research to improve the understanding of pathogenicity and immune protection in CBPP. Data should be published promptly;
Development and improvement of new vaccine strains must follow the basic rules of biological safety for recombinant vaccines;
Future vaccines should include the capability for differentiation of vaccinated and infected animals.
11. Other:
List of CBPP vaccine producers and their capabilities as established by PANVAC should be sent to the OIE and FAO.
Tools for CBPP Control - Use of Antibiotics and Diagnostic Tests
Specific Recommendations: Diagnostic Tests
12. To establish the prevalence of infection in endemic areas cross-sectional serological surveys should be undertaken.
13. To confirm the absence of disease from an area clinical surveillance (including participatory techniques), abattoir/slaughter slab surveillance and serological surveillance must be undertaken.
14. To confirm new outbreaks isolation and identification of the infectious agent must be performed. None of the serological tests on its own is sufficient as a single diagnostic test but it may be useful if serum samples from several animals are collected and tested in the CFT and the cELISA to obtain a diagnosis on herd basis.
15. Detection of antibodies and duration of detection after infection, antibiotic treatment, vaccination and multiple vaccinations are important parameters and must be clearly defined. Insufficient information on the influence of antibiotic treatment and multiple vaccinations is a constraint that must be addressed.
16. For the confirmation of outbreaks and the early detection of circulating antigen penside tests are very useful. The existing tests need validation and if adequate should be transformed into robust tests to minimize operator bias and errors. More specific and sensitive tests based on the early fraction of the capsular polysaccharides (CPS) needs further assessment before it can be validated at the field level.
17. Quality assurance of the CFT is difficult. Standardized reagents and internal quality controls (high/low titre sera with a defined titre, borderline negative sera) should be introduced to limit the variation. The joint Division of FAO/IAEA, Vienna, should coordinate this activity.
18. The immunoblotting test is highly specific and should be introduced as a confirmatory test at critical phases of CBPP control programmes.
19. The differentiation between individual animals that are infected or had been vaccinated recently is important and serological tests for this purpose should be developed.
20. The CFT is more useful for the early diagnosis of infection; however, an ELISA that is capable of detecting animals at an early stage of infection would be highly desirable.
21. The quality assurance of diagnostic results is critical, and the joint Division of FAO/IAEA, Vienna should undertake its coordination.
Specific Recommendations: Antibiotics
I. Pilot trials
Introduction:
IBAR/PACE has recently commissioned studies of CBPP epidemiology that accessed indigenous knowledge of pastoral communities to construct mathematical models. Sufficient understanding has accrued from these studies to suggest that a new paradigm for CBPP control using antibiotics should be investigated. The prospective benefits are such that pilot trials should be established without delay.
Considerations and Specific Recommendations
The target populations, at least initially, are the pastoral communities of eastern, central and western Africa. The trials proposed need to be based on the use of antibiotics to treat acute cases and elective vaccination. Two scenarios in pastoral communities should be studied; in order of priority these are:
Management of endemic disease;
with regard to the use of antibiotics as a therapeutic intervention;
with regard to vaccination and the possible influence of antibiotics on the immune response;
Management of acute disease from recent introduction;
In devising protocols to be followed, the antibiotics used will need to be selected carefully to ensure that:
Recently developed, and potentially more effective, mycoplasmacidal, chemotherapeutic agents are included;
Care is taken to avoid repercussions of the future use of chemotherapeutic agents for human.
22. PACE with FAO should embark on collaborative pilot trials in 2004 by establishing a virtual working group to draw up protocols and initiate field studies to be conducted in close collaboration with the national authorities in key countries. The collaborating partners should communicate with the pharmaceutical industry to obtain their inputs in protocol development and possible co-financing of studies. Thus, there should be three phases of the trials:
(a) Preparatory phase: establishment of virtual working group - establish dialogue between partners and with the pharmaceutical industry; development of protocols, define logistics, source funding;
(b) Study phase - overseen by PACE national programmes;
(c) Analytical phase with final report produced after a workshop.
II. Studies on microbial sensitivity
Introduction
In order to facilitate the selection of candidate chemotherapeutic agents and to understand better the existing situation, there is a need to carry out MIC and MMC studies on current African strains of Mycoplasma mycoides subspecies mycoides SC.
Considerations and Specific Recommendation
The UK Veterinary Laboratories Agency has the relevant technologies and is provisionally interested to conduct this work within its existing mycoplasma research programme. The most important constraint which needs to be overcome is that VLA lacks the field strains required.
23. The Veterinary Laboratories Agency (VLA) management should be requested by FAO and AU-IBAR to conduct the study and the FAO/OIE World Reference Laboratory for CBPP be requested to make available to VLA, the required strains.
III. Studies on the Safety and Impact of Antibiotics on the Consumer
Introduction
The widespread use of antibiotics and their control are increasingly important for the safety of livestock products in developing countries.
Considerations and Specific Recommendation
Antibiotic residues in milk and meat products have been widely studied but no efficient systems to monitor and enforce their recommended use in developing countries are in place.
24. Monitoring systems for antibiotic residues and systems aimed at achieving compliance with the recommended use of antibiotics should be encouraged to minimize the impact of antibiotic residues on the consumer.
