EUFMD 

33rd Session

Report

Appendix 01

Appendix 02

Appendix 03

Appendix 04

Appendix 05

Appendix 06

Appendix 07

Appendix 09

Appendix 10

Appendix 11

Appendix 12

Appendix 13

Appendix 14

Appendix 15

Appendix 16

Appendix 17

Appendix 18

Appendix 19

Appendix 20

Appendix 21

Appendix 9 - THE GLOBAL STATUS OF FOOT-AND-MOUTH DISEASE AND ITS RELEVANCE TO CONTROL AND ERADICATION EFFORTS IN SOUTH-EAST ASIA

Extract of a paper presented at the 5th meeting of the SEAFMD Sub-Commission, Cambodia,

22-26 February 1999

A I Donaldson, Institute for Animal Health, Pirbright, Woking, Surrey GU24 ONF, UK.

Relevance of the experiences of other regions to South East Asia

Since FMD has been controlled and eradicated from most of Europe and a large part of South America the focus for control and eradication has shifted to South East Asia. The drive for this has come from different quarters: from international organisations and from individual countries which have recognised the need to increase agricultural productivity to meet the demands for more protein to feed the rapidly expanding populations; from certain countries which want to eradicate the disease to increase their hard currency earnings through increased export, in particular of pig meat and pork products to Japan; and finally pressure from vaccine producers who face a declining market elsewhere.

South East Asia can learn lessons from the experiences gained in the control and eradication of FMD in other regions of the world but lessons can also be learnt from campaigns within South-East Asia itself, for example from the experiences of Indonesia which mounted a very successful programme during the 1974-81 which lead to the eradication of the disease from Bali and Madura in 1978, and from South Sulawesi and East Java in 1981. The last case of FMD was reported in Kebumen, Central Java in December 1983, while the last vaccination in Java against FMD was at the end of 1985. All of Indonesia was declared free in 1986 (Soehadji and Setyaningsih 1994).

The successful campaigns in Europe, including the former USSR, South America, southern Africa and Indonesia have certain elements in common which should be considered when plans are being formulated to control and eradicate FMD in the South-East Asian region. These include:

- each of the countries of the region should formulate a national plan for the control and eradication of FMD which has the legal and financial support of the government and the appropriate resources at all levels i.e. personnel and technical support, to effectively undertake and sustain the activities of the campaign through to the achievement of its final objectives. Guidelines for formulating national contingency plans for FMD have been provided in a document prepared jointly by the CEC, OIE and the European Commission for the Control of FMD and published by FAO (Report 1993).

- the technical requirements of the campaign i.e. surveillance, diagnosis, implementation of control measures, vaccine availability and delivery systems etc. must be given sufficient resources if they are to be effective. There should be a central fund which is protected against the possibility of regional economic crises.

- from the earliest possible stage, representatives of the livestock industry in each country should be invited to participate in control campaigns and be involved in decision-making at all levels.

- countries in the region should benefit, especially those which share land borders with their neighbours, from the establishment of regional groups to develop common control strategies.

- the control of the movement of livestock within and between countries will be essential if the areas which have achieved a high health status are to be protected against re-introductions of virus from areas of lower status. This will require a knowledge of livestock trade movements and probably check-points and barriers to reinforce the controls. Colour-coded ear-tags have been found to be a useful in several parts of the world for identifying the origin of animals and in helping to deter illegal movement.

- adequate supplies of safe, potent vaccines of appropriate antigenic specificity are essential to reduce the prevalence of disease to levels where it will be economically acceptable to cease vaccination, implement stamping out and move towards the final goal of virus eradication.

- campaigns should have a publicity group whose main responsibility is to ensure that farming communities and the livestock industry are aware of the campaign and its potential benefits.

- the progress of a campaign should be evaluated at regular intervals including the production of "running" cost-benefit analyses.

Requirements for control which are unique to South East Asia

The domestic livestock in South East Asia have some special features. The domestic pig predominates throughout the region and the water buffalo population is more numerous there than in other parts of the world. Pigs, especially, play an important role in the epidemiology of the disease and so there is a requirement for safe, good quality vaccines in sufficient quantity to protect them. There is a need for the establishment of internationally accepted protocols for testing FMD vaccines for pigs and for an independent body to take responsibility for overseeing the procedures. These shortcomings were clearly illustrated during the 1997 FMD epidemic in Taiwan Province of China and highlighted during the last meeting of the OIE Sub-Commission for FMD in South East Asia (Report 1998). The issues have been brought to the attention of the OIE Standards Commission and the proposals of that body are awaited.

Infected pigs have been defined as amplifier hosts for FMD virus (Sellers and Parker 1969). In the European context this was with reference to the role of the pig in excreting enormous quantities of airborne FMD virus, which under certain climatic and epidemiological conditions can result in an explosive spread of the disease. While the evidence suggests that airborne spread of FMD is not a common event in South East Asia, the pig still fits the definition of an amplifier host in that it is frequently the species which is primarily infected by virus circulating in contaminated waste food which then leads to the initiation of outbreaks. The adoption of procedures to prevent the spread of FMD virus through waste food will be essential if the virus is to be eradicated from South East Asia.

An other feature of the epidemiology of FMD which appears to be currently unique to South East Asia is the occurrence of species-adapted strains, in particular strains which are highly adapted to pigs. This has been recognised in Taiwan Province of China, The Philippines and Vietnam (Dunn and Donaldson 1997; Report 1998a). The capability of pig-adapted strains to cause very serious economic impact and the need for an early warning of their presence, therefore, were highlighted at the last meeting of the OIE Sub-Commission for Foot and Mouth Disease in South-East Asia (Report 1998a).

The part which the water buffalo plays in the epidemiology of FMD in South East Asia has not been fully investigated and is worthy of further attention, especially to know more about the maintenance and persistence of FMD virus in that species and whether there are special requirements for vaccines to be effective.

Diagnostic requirements to accelerate FMD control in South East Asia

Under the FAO/IAEA sponsored Coordinated Research Programme entitled "Improved diagnosis and control of FMD in South East Asia using ELISA-based technologies" the methods required to detect FMD viral antigen and antibody were successfully introduced into the national FMD laboratories of South East Asia. The priority activity for the laboratories of the region should be to use their diagnostic and surveillance capabilities to support national control and eradication schemes. The veterinary authorities should ensure that their field officers make maximum use of laboratory support to investigate all suspected cases of FMD. Unfortunately, at present the number of samples being collected is too few in most of the countries in the region for conclusions to be drawn about the true prevalence and incidence of disease and for assessments to be made about the appropriateness of the antigens in vaccines. When outbreaks occur, therefore, judgement of the suitability of vaccine is based on whether vaccination prevents further spread or not. This is a high risk strategy and one which will need to be changed if control is to be more effective. Planning and accurate costing of resources for campaigns will not be possible until comprehensive and reliable surveillance data are available.

When national laboratories are routinely using their diagnostic and surveillance tests they should consider expanding their capabilities to acquire a tissue culture capability. A few laboratories have already taken this step. A tissue capability enables a laboratory to isolate viruses from field samples, to grow them and send aliquots to the regional laboratory or the WRL for antigenic and genomic analyses. Laboratories with the capability can also confirm ELISA results by using virus neutralisation tests. The liquid phase blocking ELISA is highly sensitive and ideal for screening large numbers of serum samples. However, a small number of samples will inevitably give equivocal results and so further testing by virus neutralisation, the definitive confirmatory test, is necessary to obtain a final result. Clearly, this requires a tissue culture capability.

The antigenic characterisation of field isolates has two functions: (i) to confirm the appropriateness of current antigens in vaccines; and (ii) to determine if there is a requirement for a new strain to be included in the vaccines. These activities fall within the remit of a regional laboratory. However, that does not preclude the possibility of a national FMD laboratory undertaking those activities should it have the capability. The WRL remains willing to provide additional support if it were required.

Nucleotide sequencing has been shown by the WRL, some national FMD laboratories in Europe and the FMD laboratory in South Africa to be a valuable tool for identifying the origin of outbreaks. The technique is also very useful for many research activities. There would be scope to use the technique in South East Asia for molecular epidemiological purposes and possibly for research, for example to investigate the duration of persistence in the water buffalo. The method requires specialist knowledge, equipment, reagents and access to sequence data banks. It is expensive and so the potential benefits would have to be balanced against the cost. In the author's opinion, Malaysia, The Philippines and Thailand are countries where there would be grounds for using the technique primarily for molecular epidemiological investigations of the origin of outbreaks.

Donaldson and Kihm (1996) reviewed developments in diagnostic methods and other techniques which could accelerate the control and eradication of FMD. They pointed to the need for a reliable, practical, rapid and sensitive method to differentiate infected from vaccinated animals. The applications of the test are two-fold. Firstly, when a country or zone has not reported any outbreaks of disease for some months and the veterinary authority is considering the possibility of ceasing vaccination then the test can be used to verify that virus is no longer circulating. Secondly, when an FMD-free country or zone experiences an outbreak and uses emergency ring vaccination in the face of disease the test can be employed to test vaccinated animals before they are allowed to leave the vaccination zone to ensure that they are not carrying virus. In the South East Asian context the author suggests that there would be applications for the test in The Philippines, Malaysia and Thailand.

Several different types of test have been developed to differentiate infected from vaccinated animals. Most depend on the fact that cattle which have been infected with FMD virus can be differentiated from those which have been vaccinated on the basis of the detection of antibody to one or more of the non-structural (NS) proteins of the virus. During the period 1994-97 the CEC sponsored a concerted action programme in which several EU laboratories collaborated to investigate the potential of using assays measuring antibody to the NS proteins of FMD virus to differentiate infected from vaccinated animals. A number of national FMD laboratories world-wide pursued similar objectives during the same period. At a meeting held at the Institute for Animal Science and Health, Lelysad, The Netherlands on 28th and 29th April 1997 the findings were presented and discussed (Report 1998b). The most promising results have been obtained with an indirect ELISA which uses as antigen the NS polyprotein 3ABC expressed as a fusion protein in E. coli. Measuring antibody to 3ABC on a herd basis is useful to detect exposure of vaccinated herds to live virus and herds so identified can then be examined for the presence of virus. However, there are serious limitations to the reliability of the use of antibody to NS proteins for the detection of carrier animals, especially at the individual animal rather than the herd level, and further work in this area is required. Presumably this will be among the topics which will be addressed during the next FAO/IAEA Coordinated Research Programme.

References

Donaldson A I and Kihm U (1996) Research and technological developments required for more rapid control and eradication of foot and mouth disease. Rev. sci. tech. Off. int. Epiz., 15 (3), 863-873.

Dunn C S and Donaldson A I (1997) Natural adaptation to pigs of a Taiwanese isolate of foot-and-mouth disease virus. Vet. Rec., 141, 174-175.

Report (1993) Report of the Thirtieth Session of the European Commission for the Control of Foot-and-Mouth Disease. Rome, 27-30 April 1993. FAO, Rome. pp48-62.

Report (1998a) Report of the Fourth Meeting of the OIE Sub-Commission for Foot and Mouth Disease in South-East Asia with the Participation of FAO/IAEA. Bangkok, Thailand. 3-6 March 1998.

Report (1998b) Proceedings of the Final Meeting of Concerted Action CT93 0909. The Veterinary Quarterly, 20, Suppl 2, May 1998, S1-40.

Sellers R F and Parker J (1969) Airborne excretion of foot-and-mouth disease virus. J. Hyg., Camb.,67, 671-677.

Soehadji M M and Setyaningsih H (1994) The experiences of Indonesia in the control and eradication of foot-and-mouth disease. In Diagnosis and Epidemiology of Foot-and-Mouth Disease in Southeast Asia. Proceedings of an International Workshop, Lampang, Thailand, 6-9 September 1993. Editors J W Copland, L J Gleeson and Chanpen Chamnanpool. ACIAR Proceedings No.51. pp64-69.

© European Commission for the Control of Foot-and-Mouth Disease

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