Summary
According to the assessment made by the Epidemiological Unit of PACE, CBPP is endemic in many parts of Africa. However, the lack of data made this assessment and accurate zoning of disease distribution difficult. There was a pressing need for prevalence data to confirm zoning. The reasons for the persistence of CBPP were attributed to animal movement within and between countries. Other reasons were, the absence of adequate diagnostic tests, the lack of use of diagnostic tests because of diminished financial support and a downturn in the use and quality of CBPP vaccine. Therefore, efforts to build diagnostic capacity were required. A regional approach that takes into account differences in epidemiological situations, the provision of training, and veterinary surveillance for the disease at borders was proposed. A draft project proposal was summarised where surveillance, quarantine and serological screening were advocated for free zones. These together with ring vaccination with branding of vaccinated cattle were promoted for newly affected areas. The use of harmonised mass vaccination and antibiotic treatment for 5 years were proposed for enzootic zones. All efforts should be made to minimize the likelihood of the reintroduction of CBPP into free areas by the establishment of buffer and surveillance zones.
The recent resurgence of CBPP in Africa was attributed to the lack of funding. Animal losses in Africa due to this disease were estimated to be about US$ 2 billion. The threats to CBPP-free countries from affected areas within the SADC members were emphasised. The effects of CBPP infections were felt at several levels i.e. at household, national and regional levels but losses were likely to affect food sources and draft power leading to significant hardships at the household level. In Botswana, this sector suffered 80% of the losses and therefore efforts to keep this area free of incursions of CBPP were strongly reiterated. The endemic epidemiological clusters of CBPP in Angola and Tanzania were noted. Illegal cattle movement, ineffective vaccination campaigns, and the lack of contingency plans were identified as the immediate challenges to effective CBPP control. Plans for ‘the way forward’ included the development of a phased strategy where emergency and recovery phases that were designed for the containment of disease were explained. A 16-year guideline/plan for the progression from control of the disease from primary endemic foci infection to freedom from disease was discussed.
A participatory modelling study that was based in Northern Tanzania, and Sudan, was conducted by PACE/CAPE to gather information about the dynamics of cattle movement within the local communities. The complex social interactions that involved animal movement and the transmission of CBPP in a herd were modelled by using field data, and information available in the literature, respectively. Simulations from these models predicted that CBPP could persist indefinitely in small, interlinked herds of 50 head, or in single herds of 300 head. These data supported the requirement for quarantine to interrupt the transmission cycle. However, this was deemed to be unrealistic in pastoral communities. Simulation of mass vaccination showed control but not elimination of disease and thus would not achieve eradication of CBPP. Elective vaccination was proposed because the model predicted a short-term benefit to the owner, but liberalisation in the availability of the vaccine would be required in this case. Effective treatment, according to the model, was of more benefit than vaccination because it reduced persistence of disease in herds. Near eradication was predicted by combined programmes of effective vaccination and treatment.
A longitudinal serological study conducted in the Ethiopian highlands was used in mathematical model work on the spread of CBPP disease. Of the 71 herds that were followed for about one and a half years, 35 were infected with CBPP. Fifteen of them were classified as newly infected and used in a serological and clinical incidence study. Cumulative risks of seroconversion over 8 and 16 months were calculated to be 26 % and 34 %. In these herds, the average serological, clinical, and mortality incidences were 34%, 39% and 13%. These were lower than those reported in the literature (70%, 30-70%, 10-80%, respectively), but there were no obvious explanation for this finding. They could have been MmmSC strain or cattle breed related..Although 50% of the herds were treated with single injections of oxytetracycline, no effect from this was seen or could be shown statistically. The possibilities of underdosage and reduced antibiotic quality were proposed for these observations. Further studies were required to resolve these issues. Two disease transmission models were proposed, one that included the possibilities of interactions from animals with sequestra and another, simpler one that excluded these. Simulations from these provided estimations of transmissibility when periods of susceptibility or latency were varied, but many more simulations were necessary before firm conclusions could be made. More data were necessary to confirm mathematical situations e.g. the transmission from chronic carriers, and effects of antibiotic treatment.
Discussion
In drawing up strategic control policies based on epidemiological data, or contingency plans, mathematical models for transmission and disease situation based on experimental or field data, the common fact and a stumbling block was the lack of reliable data. Considering the method of livestock production in Africa i.e. mainly transhumance, it was difficult to set up surveillance to gather epidemiological data. This reality and the fact that veterinary structures have been disrupted due to budgetary constraints made the setting and implementation of control strategies difficult.
Conventional and new approaches for CBPP control were discussed. It was obvious that movement control at the level that was practiced in the 60s was not possible today, and the control of CBPP may be more costly than the losses from the disease itself. Longitudinal studies and computational modelling, could be carried out in other countries and would account for the different livestock situations in different countries. These required accurate data to be useful. The observed seasonality in the incidence of CBPP in come herds in Kenya herds was surprising; owners described this seasonality which may have been due to mixing or weather patterns, but there was no supportive data.
The effectiveness of antibiotic therapy was questioned because no clear basis for its use was demonstrated. There were conflicting cases made for the consequences for the use of any antibiotics, but the potential impact was presented and the urgent need for more field research was highlighted. Antibiotics that are bacteriostatic cannot eradicate the disease but they may have a significant effect in the reduction of infection or the transmission of infection. Thus mathematical models including these factors could be used to test the potential benefits of therapy. Absolute quarantine as a way of transmission control was possible but not practical and models would be able to predict the epidemiological outcomes as the infection rates varied.
Heated debate ensued on proposals for the use of elective vaccination. As CBPP is a notifiable disease and prophylactic measures are obligatory, caution was expressed in the use of elective vaccination as a CBPP disease control option.
Summary
Toxins have not yet been described for MmmSC nor have virulence factors, but potentially galactan, variable surface proteins, lipoproteins, transporter proteins and adhesions may modify virulence. These classes of proteins were major antigens and many are located on the surface of the organism and thus suitable targets for molecular manipulation towards the production of vaccine. The lipoprotein LppQ that was already used in a diagnostic assay exacerbated the disease when inoculated into cattle despite the fact that it is present in current vaccines. ABC transporters and associated systems for the export and import of molecules could influence virulence such as the glycerol uptake and metabolic system. In Mmm SC, especially in African/Australian strains, this system is capable of producing relatively large amounts of peroxidase, which, given the close cell to host cell association of mycoplasmas, results in the induction of apoptosis of the host cell. Several generic targets for vaccines and methods for their production were considered and discussed.
Two new preparations of dead vaccines were tested for their protective ability. One was saponised, whole-cell MmmSC, and the other was purified LppQ ISCOM.. They were inoculated separately into cattle that were subsequently challenged with a local field strain of MmmSC. Both preparations did not elicit specific antibody responses. After challenge, it was observed that there was disease severity as judged by the extent of lung lesions compared to experimentally infected controls that had not been vaccinated. The animals appeared to have been sensitised.
Improved vaccines could probably make the major contribution to CBPP control. Towards this goal, the immune responses of two vaccine preparations, T1 44 and a saponised virulent field strain, were studied for their ability to elicit specific antibody and lymphoproliferative responses. Preliminary results showed that antibodies were elicited by both preparations and a single inoculation with the saponised strain produced responses similar to a booster with T1 44. Various antigens produced varying degrees of proliferative responses from lymphocytes. Cell populations remained similar throughout the course of vaccination.
Does T1 44 revert to virulence? Every now and then but with unpredictable frequency, some T1 44 vaccinated cattle develop Wilhelm’s reactions at the site of inoculation. These reactions are not caused by subsequent vaccinations with T1 44 vaccines. The reactions range in severity and can be cured with antibiotic treatment. A study to assess if this phenomenon was due to differences in these MmmSC organisms was undertaken. The vaccine T1 44, a local field strain of MmmSC and an MmmSC organism named T1 B, isolated from a vaccination reaction site, were re-inoculated into cattle that were monitored clinically. T1 44 did not cause any local reactions, but field strains and T1 B caused large local reactions and fever. T1 B behaved like the local field strain. MmmSC was also re-isolated from these lesions. Protein profiles of these organisms were compared using SDS-PAGE. Changes in the high molecular weight range between T1 44 and T1 B were observed. The significance of these differences was not known at the moment.
The apparent failure of the T1 44 vaccine in Botswana could have been due to incorrect vaccine seed strain, insufficient vaccine titre, or underdosage. Studies showed that the strain was correct, and further experiments were undertaken to study the dose and its protective effect. There were no significant differences between doses from 107 to 109 organisms; mortality rate in controls was about 30% compared to about 6% in vaccinated animals. The severity of lesions was scored. A reduction in that score in the vaccinated animals showed clear protection. Variations in individual animals were observed. T1 SR was also tested and although statistical differences could not be shown, T1 44 appeared to be more protective according to the lesion scores. It was suggested that high titres were necessary to prolong the shelf life of vaccine.
With the current CBPP situation in Africa, the two options for CBPP control actions are either “accept it” i.e. live with the disease or “control/eradicate it”. To live with CBPP is politically unacceptable because the use of antibiotics would increase while production and income would decrease. To eradicate CBPP would involve losses through stamping out and movement restrictions. The only realistic option for Africa is vaccination and the two options are to develop new vaccines or to use existing ones. The development of new vaccines would be costly and may require many years of research efforts. Efficacy, production and political issues would have to be resolved before meaningful progress could be made. The biggest issue however, is that of funding. Who would fund vaccine development/research? Therefore, the way forward is to improve existing vaccines by increasing their thermal stability, viability and immunogenicity. This is certainly possible because vaccines used in Australia were stable at 37°C. Improvements may be made by i) increasing the buffering capacity of media used in vaccine production by the inclusion of HEPES, ii) discontinuing the use of Magnesium Sulphate (MgSO4) in the reconstitution buffer because it causes a pH change leading to decrease in viability of mycoplasma organisms and iii) use phosphate buffered saline as diluent. Inclusion of a pH indicator could help monitor shift in pH after vaccine reconstitution. These simple technical changes with proper funding for production and quality control, could improve the efficacy of current vaccines significantly.
Discussion
Current research must not to be abandoned because it could also lead to better vaccines and diagnostic tools. Applied research to improve the stability of T1 44 vaccine were urgently needed. There are good opportunities to improve vaccine products and these may be made by simple modifications in the formulation including the reconstitution buffer, attenuation of strains by genetic modification and minimization of adverse reactions.
FAO has commissioned work using xerovac vaccine technology, in which trehalose is used to improve vaccine stability at higher temperatures, that may not require the need for cold chain storage.This work should be published and the work taken further. The simple but crucial observation of adverse effects of reconstitution with buffer containing magnesium sulphate (MgSO4) sparked much discussion. Perhaps it would be relatively simple to change the buffer, but caution and further work to check the viability of organisms was recommended before these methods were standardized. The effect of MgSO4 buffer was questioned. It was suggested that this diluent was added to measles and rinderpest vaccine and afforded some thermal protection. However, the effect of MgSO4 on CBPP vaccine would also have to be investigated. It was recognized that this solution was widely used as reconstitution buffer for other vaccines without any adverse effects. It was also argued that MgSO4 did not inactivate the vaccine but drop in pH caused a rapid decrease in the viability of the organisms. Perhaps viability was not a problem for other vaccines used. Therefore, if the vaccine formulation was better buffered e.g. with HEPES, then the pH would be stable enough not to cause the loss in viability. A different reconstitution buffer such as phosphate buffered saline would also overcome this problem. A pH indicator in the buffer could also help to verify the correct pH after reconstitution. Such information suggesting practical changes could be disseminated very quickly and manufacturers could make the necessary adjustments to production equally fast, but pilot studies were required to show the effects of HEPES and MgSO4 in field conditions of Africa. In fact many of these ideas would require experimental validations and changes in the standard methods of production of existing vaccine would require retesting for efficacy etc. No funds are yet available for this activity from international donors.
Methods to improve vaccines by genetic modifications were also available, but the genes that lead to attenuation are not always virulence genes and may not be those essential for eliciting Wilhems reaction.
The apparent reversion of T1 44 to T1 B that consistently caused tissue reactions at the site of injection prompted much debate. How stable was this reversion? The reaction happened after the 2nd passage; T1 B was still virulent after 2 in vitro passages. The pahogenicity of T1 B was not known. One criticism was that T1 B was not purified and so the inoculum may have contained wild type strains of MmmSC and therefore Koch’s postulates were not fulfilled for this isolate. In fact this was a safety study and not a virulence study and only one batch of vaccine was used. Why was reversion occurring in animals but not in vitro e.g. during vaccine production? OIE guidelines stipulate that vaccine strains have to undergo two passages from the grandparent stock, thus in culture there is no pressure for much change. In animals, there is selection of more virulent strains at the expense of less virulent strains..
In the field, tissue reactions after vaccination with T1 44 were seen in Kenya but none in Namibia, Cameroon and Chad. The unpredictable nature of the incidence of reactions could not be explained.
Summary
An optimistic view of the research trends driven by technological advances in molecular biology e.g. higher throughput capacity of sequencing was given. In fact the genome of the type strain of MmmSC has been sequenced, but its origin and virulence are doubtful. No obvious virulence factors have been identified. The comparison of attenuated and virulent strains in terms of the production of protein i.e. proteomics, may establish virulence factors. The expected benefits from these types of studies on pathogen/host relationships and immuno-pathogenesis are, better vaccines and diagnostic tests. Other important areas of research were the description of transmission factors, usefulness of antibiotics, types and appropriateness of surveillance systems and control strategies, and computational models (because there are no animal models for simulating CBPP disease).
Antibiotics are officially forbidden for use in CBPP but nevertheless still used often in the field. The in vitro activity of some of these is known but little information exists on their in vivo activities on MmmSC. The activity of tetracycline that is used most often was studied in the field.
Preliminary results showed that it reduced inflammation at the inoculation site but did not prevent infection. It reduced the severity of lung lesions but did not prevent them, and the pathogen was able to persist in the host. In the field where the quality and dosage of the antibiotic may not be optimal, these effects may not be sufficient for effective treatment of CBPP disease. Therefore, tetracycline has no place in eradication campaigns but may be of some benefit together with vaccination campaigns e.g. in the control of post-vaccination reactions.
The results of an FAO/IAEA Co-ordinated Research Project (CRP) on the “Monitoring of contagious bovine pleuropneumonia (CBPP) in Africa using enzyme immunoassays” showed that the complement fixation test (CFT) and a competitive ELISA for the detection of antibodies to MmmSC were adequate tools for the monitoring and surveillance of CBPP. Although none of the validated diagnostic test was sufficient on its own, estimates of the sensitivity and specificity will allow the development of testing strategies which are suitable for the surveillance of CBPP. Detailed recommendations for a surveillance and testing strategy for different epidemiological situations were discussed. The inclusion of internal quality controls in the cELISA showed a high level of repeatability and reproducibility of the test which will ensure that test results produced by the laboratories are reliable and comparable. During the CRP, the CFT and the competitive ELISA were introduced into 11 African countries.
Portugal has successfully eradicated CBPP since its reintroduction in 1985. Strategies that led to a declaration of freedom from CBPP were as follows: accurate zonation, movement control, yearly serological surveillance from 1985 to 1994 that was increased to biannual testing between 1995 to 1997, abattoir surveillance and prompt follow up, culling of all serologically positive animals and eventual stamping out. During the first period, these measures firstly mapped the extent of the disease that was mainly in the north of the country and reduced the incidence of CBPP within these regions such that re-zonation encompassing smaller areas was feasible. The second period saw the further shrinking of these regions and a dramatic decrease in incidence. In this situation the inadequacies of CFT were unacceptable and a new confirmatory test, the immunoblotting test (IBT) was introduced to resolve the false positive results seen with the CFT. Since 1998 the CFT and IBT have been preformed serially on all sera for CBPP surveillance ensuring that an accurate diagnosis and assurance of freedom from CBPP was the prime target.
The impact of CBPP was assessed using participatory epidemiology techniques. Not only could these methods assess the relative incidences of diseases within the community, but they could also provide useful information on their importance to the owners in terms of lost production and real wealth in the absence of validated numerical data. These techniques could provide comparative impact assessments, had a proportional approach, random sampling was possible, could be standardized for valid comparisons with other populations and results could always be checked by conventional methods. Unlike conventional epidemiology that is commodity based and thus is an outsiders view, participatory epidemiology provided the insiders view that included private and sensitive information not accessible otherwise. Data gathered in Ethiopia were presented on the impact of several diseases including CBPP on cattle production.
Often, information on CBPP for research or teaching purposes is not readily available especially in many African countries. AVIS (Advanced Veterinary Information Systems) in partnership with TELOS-Aleff Ltd, the Institute of Animal Health (IAH), UK, FAO/OIE Collaborating Centre for CBPP and the FAO have developed a web-based information system that strives to rectify this. The modular nature of the system and its user friendly interface and accurate information, offered by experts in the field were demonstrated.
CBPP is the second most important disease targeted for intervention within the PACE programme, but its inclusion in this list was questioned because of the lack of supportive data. The primary objective of PACE was to persuade regional integrated policies for surveillance to accumulate this data and control activities especially in endemic regions. To this end, several meetings, consultancies and draft policy documentation were carried out from 2001 to 2003. It was evident, that there were insufficient resources within PACE countries for the eradication of CBPP, estimated to cost about €300-450 million and mass vaccination needed extensive political support. Other factors that were deterrents to CBPP control were poor vaccine quality, the lack of an in vitro test for the differentiation of vaccinated from none vaccinated animals and the deterioration of veterinary services in some countries. The impact of CBPP was difficult to estimate, as the observed and reported mortality and morbidity data alone were not significant. The use of participatory epidemiology afforded some understanding of disease dynamics. Alternative control strategies included antibiotic therapies (although the choice of therapeutic agent was not clear), elective vaccination where the private sector (owner) decided the course of action. These measures would require the liberalization of the availability of CBPP vaccines, acceptance of antibiotic therapy, training of farmers and the acceptance of this concept by veterinary services.
Discussion
Discussions on the choice and use of antibiotics questioned the use of tetracycline. Tetracycline was chosen for these studies because it was the most common antibiotic used in the field by farmers. Although it did not prevent infection and it is basically bacteriostatic, it may have a place in therapy because it may provide time for the animal to develop immunity.
The activity of other antibiotics such as tylosin was questioned. It was used in southern Sudan and could be effective. Some in vitro work was done but it was impossible to extend this to the field. Broad in vitro studies needed to be done followed by focused field work. Research was also required on the likelihood of antibiotic resistance. Some work has been done in Muguga and there was some evidence of resistance to tetracycline in Mmm SC. Research was necessary to look for the type of resistance mechanism involved and if the resistance is transferable. Antibiotics that do not sterilize but may stop symptoms could produce animals that posed further threats by transmitting the disease thus confounding the issue. The influence of antibiotics on diagnosis was not known. However, the demand for treatment was high and farmers already treat animals, so the need for a good drug regimen was important. EU regulations for exporters of meat from Africa have to critically consider the issue of antibiotic residues.
Country specific control strategiesSummary
In the late 60s there were great expectations for the control of CBPP in West Africa In the late 80s during the PARC project with mass vaccinationagainst rinderpest and CBPP, realtively few outbreaks of CBPP were encountered. The mid 90s saw a resurgence of CBPP prompting emergency activation of national and international programmes. Cattle production systems in these areas follow extensive pastoral nomadism and the spread of CBPP was assisted by uncontrolled transhumance across borders. A review of the current situation indicated that CBPP was widespread in West Africa and parts of Central Africa but the true picture of disease distribution was difficult to delineate because of imprecision in surveillance and reporting data. Guinea and Senegal have excellent surveillance systems. In some regions of Africa, laboratory capabilities were not equal or similar between countries and not balanced between peripheral and central laboratories. A review of the current control strategies showed inconsistencies in surveillance, notification and vaccination programmes between countries of the same region. Guinea and Nigeria currently have strong control measures for CBPP although the rate of vaccination decreased from 1999-2001. A phased control strategy was proposed, where building and refining epidemiological data collection, infrastructural dvelopment, community involvement in disease search and data collection, reduction of national risk by limitation of re-entry and uncontrolled movement of infected cattle, institutionalised surveillance, private and public sector involvement in CBPP disease control efforts; and regionally coordinated efforts, were defined. Strong political will and high commitment and tight co-ordination between sub-regions were identified as most important and critical factors in the success of this strategy for the control and eradication of CBPP in West and Central Africa.
Of the 16 million cattle in Nigeria, 90% were nomadically reared and 10% were intensively farmed. Transhumance is very important and CBPP in this population was most important. It caused direct and indirect losses and secondary social consequences. After virtual eradication in 1965, the disease has made a steady come-back due to civil strife or changes in socio-economic situations. There is considerable north to south movement of cattle in Nigeria and between 1995 to 2001, outbreaks increased from 8 to 31. A new policy and strategy for control were introduced comprising containment and control phases that included proper zoning, test and slaughter and vaccination with the aim of reducing CBPP incidence to 10%. Early detection, maintenance of a reporting chain, 5-year vaccination programme with minimum of 70% coverage, and liaison with neighbouring countries were the key elements of this plan.
In Angola, south of the 14th parallel is the most important endemic focus of CBPP in Southern Africa. Transhumance is a way of life and trade in livestock products, exchange of cattle for draft power, civil and military unrest all contributed to the increase and persistence of CBPP. Earlier, field vaccine, which was essentially pleural exudates, was used. This caused the spread of CBPP, but during 1970 to 1994 vaccines that were essentially T1 44 were used albeit inconsistently due to interruptions by civil strife. Recently, 2002/2003, cattle movements have been mapped out and as part of a 5 year plan, a buffer zone between the 13th and 14 parallel has been established although there cannot be physical barriers (as it is in Namibia). Other activities such as rebuilding of laboratories destroyed during the civil war, establishment of general animal health networks, veterinary services and laboratory networks are being undertaken with the help of international donor funds. It may be possible to control CBPP from Angola given political will, a well-defined animal health policy, scientific efforts to improve the vaccine and International support.
In Namibia CBPP is endemic in the northern communal region. Historically, vaccination with T1 44 has been practiced in this region but between 1995 and 1999 there was a 10-fold increase in mortality due to CBPP. This may have been due to increased transhumance, or ineffective vaccination with T1 SR, however, CBPP was kept in check by movement control. In 2003 CBPP returned to the Caprivi strip. There were 17 cases confined to the Kavango region, and an outbreak near the border with Botswana where 78 of 104 cattle were positive according to the CFT test and 80% had typical lesions. It is noteworthy that CFT was most useful test in this outbreak. Comprehensive stamping out was not possible in this case due to financial considerations but a vaccination programme was instituted.
CBPP spread from the East near Mali, to Haut Guinea and Guinea Forestiere. Mass vaccination with T1 44 was started in 1987 followed by surveys.From 1995 onwards, zoning, legislation and regulation, active participation of stakeholders, animal identification and training of herdsmen and veterinary staff, abattoir surveillance and compensation improved this strategy. Dissemination of information was essential and done through national TV and radio, through workshops and distribution of handbooks. Financial support came from government and international bodies. The programme was well supported by livestock owners and private veterinarians carried out most of the vaccination in 2002. Peak vaccination coverage was in 1997 and has decreased a little because of civil unrest. These actions resulted in the decrease in outbreaks and slaughter.
In 1999 civil strife in Angola caused an influx of refugees and their cattle into the West of Zambia. Despite some stamping out efforts CBPP spread northwards prompting zonation and vaccination. These efforts were continued and supported by setting up testing facilities and training. At present abattoir surveillance, serological surveillance and sensitisation are being carried out. Vaccination in a large area to the West has been proposed.
Discussion
The significance of CBPP was questioned by some participants earlier during this meeting. Yet during this session it was obvious that 27 countries reported the disease because there was a problem. The lack of data in the public domain was explained by the unwillingness to publish due to political concerns or the sluggish attitude towards publication. In the Caprivi of Namibia 2000 animals may be infected and it is a big problem not only for that country but also for the surrounding disease-free countries. In Zambia the situation was worsening because of disease incursions from Angola. In the past individual country strategies have not made collective difference in this region.
There are many gaps in the scientific knowledge on CBPP. Virulence factors and the genes responsible have not been identified; these genes and those that lead to a protective response must also be identified. The genes that may confer virulence or protection are not the same as those responsible for attenuation of an organism. Research towards better vaccines is important. It is also important that diagnostic research continues to distinguish between vaccinated and non-vaccinated and infected animals. The serological tests CFT and the successfully validated cELISA may perform differently in different countries, but are adequate for surveillance purposes. Sera collected for the rinderpest campaign may be used to gather this data provided that relevant CBPP data is known. The PACE Epidemiology Unit should be able to provide clarification of this. The requirements for rapid, user-friendly diagnostic tools and better vaccines are still urgent and require continuing research.
The earlier proposal of elective vaccination prompted intense and lengthy debate. It was felt that elective vaccination may break down zonation and the precision of activities within them and interfere with surveillance and diagnostic activities. These criticisms were moderated by the suggestion that free vaccination was for endemic areas only and that the mixture of mass vaccination with elective vaccination could improve coverage. No concensus was reached in adopting elective vaccination as a strategic option in the control of CBPP
Several strategies for the control and possible eradication of CBPP were presented that seemed contradictory. They reflected differences in livestock management or capacity of veterinary services the particular country or region. If policy makers in a region or locality acted synergistically, then control strategies would be poised for maximum effect. Synergism between the private and public sectors in complementary partnership would be desirable because it would be more efficient. Perhaps solutions to the problems in primary endemic areas could begin to appear. The presence of representatives from Namibia, Angola, Zambia at this meeting would provide opportunity for collaboration towards this. Therefore, despite the lack of data, but with the firm assurance from the meeting that CBPP is a significant problem, it was agreed that CBPP control should be driven ahead and proposals for control should not be postponed.
